1. Enzymes - general characteristics, structure and function. Naming and classification of enzymes.
Enzyme = apoenzyme (protein) + cofactor (prosthetic group, coenzyme, nonprotein)
Cofactor - essential ions (activator and metal ions)
- coenzymes (cosubstrates and prosthetic group)
1. Oxidoreductases - redox, alcohol dehydrogenase (NAD+ reduced to NADH, fermentation, glycolysis)
AH2 + B = A + BH2
2. Transferases - transport functional groups, kinases (phosphorylation), deaminases AX + B = A + BX
3. Hydrolases - hydrolysis reaction, proteases/peptidases (cleave bonds between aa), lipases (break down
lipids into fa and glycerol, cleaves ester bonds), nucleases (cleaves phosphodiester bonds between
nucleotide subunits in nucleic acids), AB + H2O = AH + BOH
4. Lyases - group elimination to form double bond, oxalate decarboxylase, isocitrate lyase, carboxylases,
aldolases, dehydratases, AB + XY = AX + BY (atp = camp, ppi)
5. Isomerases - isomerisation, racemases, epimerases, isomerases, alanine racemase, glucose-6phosphate isomerase, A = A’
6. Ligases - bound formation with ATP hydrolysis, DNA ligase (forming phosphodiester bonds) A + B = AB
2. Catalysis of biochemical reactions. Mechanism of enzyme function. Specificity of enzymes.
Enzyme catalysis is the increase in the rate of a chemical reaction by the active site of a protein. The
protein catalyst (enzyme) may be part of a multi-subunit complex and transiently of permanently associate
with a cofactor.
Enzyme’s active site binds to substrate, increasing T increases rate of reaction, but dramatic changes can
denature enzyme. When enzyme binds it’s substrate it forms an enzyme-substrate complex and lower
activation E of the reaction.
Enzyme will always return to it’s original state at the completion of the reaction.
Specificity - selectivity of enzyme to their substrate. Ability to of an enzyme to choose exact substrate from a
group of similar chemical molecules, is actually a molecular recognition mechanism and it operates through
the structural and conformational complementarity between enzyme and substrate. Specificity: bond, group,
substrate, optical, geometrical, co-factor.
Factors affecting enzyme catalyzed reaction - substrate and enzyme concentration, T, pH, inhibitors,
activators.
3. Constitutive and inductive enzymes, repression of enzymes, regulation of enzymatic activity.
Constitutive - produced all the time in the cell, not controlled by induction or repression, concentration of
these enzymes doesn’t depend on inducers.
Inductive - expressed only under conditions, concentration of these enzymes depends on the presence of
inducers (lactase enzyme in bacteria grown on glucose media).
Enzyme inducer - type of drug that increases the metabolic activity of an enzyme by binding to the enzyme
and activating it. or by increasing the expression of the gene coding for the enzyme.
Enzyme repression - prevention of enzyme synthesis within a cell. Protein molecule known as a repressor,
binds to region of DNA called operator responsible for synth messenger ribonucleic acid necessary for
building a protein. Repressor blocks mRNA from forming, which stops the production of enzymes.
Regulation:
- inhibitors - reversible noncovalent, irreversible covalent, inhibition (competetive binds to E acitive center,
noncompetative binds to E or ES changing comformation. uncompetetive binds to ES complex)
- allosteric regulation - positive when increases enzyme activity, negative if decreases
- covalent regulation - methylation, hydroxylation, adenylation, phosphorylation
- feedback inhibition - end product directly inhibits an enzyme early in biosynthetic pathways
- proenzymes - pepsinogen, trypsinogen, chymotrypsynogen, prothrombin, clotting factors)
- protein-protein interaction (inactive form)
4. Kinetics of enzymatic reactions. Michaelis constant Km. Inhibition of enzymatic reactions.
Enzyme kinetics - rate/velocity, rate constant, rate of law, order of a reaction, molecularity of a reaction
Factors - substrate and enzyme concentration, T, pH, inhibitors, activators.
Michaelis constant - kinetic constant, relation between concentration and velocity
1/v = 1/Vmax + Km/Vmax * 1/[S]
- inhibitors - reversible noncovalent, irreversible covalent, inhibition (competetive binds to E acitive
center, noncompetative binds to E or ES changing comformation. uncompetetive binds to ES complex)
5. Allosteric enzymes - effectors and inhibitors, importance in metabolism.
Allosteric enzymes - two binding sites - substrate of the enzyme and effector.
Effectors - small molecules which modulate the enzyme activity, reversible function (noncovalent
binding in allosteric site).
Function - activation or inhibition of an enzyme by a small regulatory molecules that incteracts at the
site (allosteric site) other than the active site (at which catalystic activity occurs). Interaction changes
the shape of the enzyme so as to affect the formation at the active site of the usual complex between
enzyme and its substrate.
Regulatory molecule may be a product of a synthetic pathway and inhibit an enzyme in that pathway
(feedback inhibition) thereby preventing the further formation of itself. Other act as a activators, binding
of the substrate to the enzyme, enhancing catalytic acitivity.
Adenyl cyclase activates hormone adrenaline which is realase when a mammal requires energy,
catalyzes reaction that results in the formation of the compound cyclic AMP (hydrophilic
neutrotransmitter). cAmp activates enzymes that metabolize carbonhydrates for energy production.
Combination of allosteric activation and inhibition provides a way by which the cell can rapidly regulate
needed substances.
6. Coenzymes – classification, structure, function.
Coenzymes are small organic molecules that link to enzymes and whose presence is essential to the
activity of those enzymes. Belong to larger group called cofactors (metal ions, small molecules, nonprotein).
Many coenzymes are derived from vitamins. Examples: TPP, FAD, CoA, PLP, NAD+, Tetrahydrofolate,
Biotin.
Cofactors can be coenzymes which can be loosely bound. Coenzymes are usually realased from the
active site of the enzyme.
Function - transport groups between enzymes (hydride ions by NAD, phosphate groups carried by
ATP, acetyl by CoA).
Cofactors:
-coenzymes
- essentail ions
- loosely bound forming metal activated enzymes
- cofactor tighty bound is termes a prosthetic group, forming matalloenzymes
- inactive enzyme without cofactor is called apoenzyme
- complete enzyme with cofactor is holoenzyme
- 2 loosely bound cosubstrates
7. Formation and toxicity of ROS and NOS. Antioxidants (enzymatic – and low molecular
antioxidative systems), the role in living systems.
ROS are chemically reactive molecules containing oxygen (peroxidases, superoxide), formed as a
natural byproduct of the normal matabolism of oxygen and have imporant roles in cell signaling and
homeostasis. But during times of enviromental stress (UV, heat exposure, ionizing radiation) ROS
levels can increase dramatically, that can provide damage of the cell structure.
NOS nitric oxide synthetase
Toxicity results - damage of DNA, oxidations of polyunsaturated FA and lipids, oxidation of aa in
proteins.
Cells balance negative effects of ROS by producing antioxidants such as GSH, TRX which reduce
power of NADPH.
Antioxidative system - not to remove oxidants but keep them at an optimum level. Example
superoxide realased by oxidative phosphorylation is first converted to hydrogen peroxide and then
reduced to water. This detoxification pathway is the result of multiple enzymes with superoxide
dimutases catalysing the first srep and then catalases and various peroxidases removing H2O2.
8. Respiration chain – composition, function, inhibitors. Electrons and H+ transport – oxidative
phosphorylation, ATP-ase, uncouplers.
- Composition - electron transport (carried by reduced coenzymes, generation of proton gradient accross
the inner mitochondrial membrane), oxidative phosphorylation (proton gradient runs downhill to drive the
synthesis of ATP). Take place in inner mitochondrial membrane.
COMPLEX I - inhibitor retenone amytal, NADH -> Ubiquinone + 2e- (NADH dehydrogenase), cofactors FMN, Fe-S, 4 H+, NADH+
COMPLEX II
- inhibitor - malonate; Succinic acid -> Fumaric acid -> FAD -> Ubiquinone (succinate-CoQ reductase);
cofactors - FAD, cyt b560, Fe-S, - OH+, FADH2
COMPLEX III
- inhibitor - antimycin A; Ubiquinone -> cytC (CoQ-cyt c reductase); cofactors - cyt bh, cyt b2, Fe-S
- 4H+
COMPLEX IV
- inhibitor - cyanide, CO, azide; cyt C -> O2 (cytochrome oxidase, atp synthetase); cofactors - cyt a, cyt
a3, CuA, CuB; 2H+
COMPLEX V ATP
- inhibitor - oligomycin; 3H+, ATP; non spontaneus atp synthesis is coupled to spontaneus H+ transport
into the matrix, pH and electrical gradients created by respiration are the driving force for H+ uptake
- ADP + Pi -> ATP
- Function - transfering electrons from donors to acceptors via redox, and couples this electron transfer
with the transfer of protons acrossa membrane, this creates an electrochemical proton gradient that
drives synthesis of ATP.
- Uncouplers - shuttle back and forth accros the membrane carrying protons to distract the gradient,
example is salicylic acids that decrease prod of ATP and increase body T. It’s obligatory linkage
between respiratory chain and phosphorylation system.
9.
Phosphorylation on substrate level. Macroergic compounds.
Substrate-level phosphorylation is a process of energy coupling of an exogenic reaction with ATP synthesis
from ADP and Pi. Two reactions during glycolysis - PEP to pyruvate and 1,3-bisphosphoglycerate to 3phosphoglycerate and one is a part of citric acid cycle - succinyl-CoA to succinate by thiokinase.
Another examples - working skeletal muscles and brain where phosphocreatine is stored - p-creatine to
cretinine + ATP.
- fermentation - butyric acid fermentation and propanoic acid fermentation.
10. Citric acid cycle – the action, importance, amfibolic character, regulation.
Chemical reactions used in aerobic organisms to generate energy through the oxidation of acetyl-CoA
derivated from carbohydrates, fats, proteins into CO2 and chemical energy in the form of GTP.
It’s a key metabolic pathway that standarize carbonhydrate, fat and protein metabolism.
Amphibolic character - involve catabolic and anabolic processes.
Anabolic - condensation of acetylCoA and oxaloacetate to yield citric acid the tricarboxylic acid of the cycle.
Catabolic - two molecules of CO2 are released (isocitrate dehydrogenase and alfaketoglutarate
dehydrogenase complex step), and oxaloacetate is regenerated commencing another cycle.
Regulation - reduced amount of ADP causes accumulation of precursor NADH which in turn can inhibit a
number of enzymes. NADH, a product of all dehydrogenases in the TCA cycle with the exception of
succinate dehydrogenase, inhibits pyruvate dehydrogenase, isocitrate dehydrogenase, α-ketoglutarate
dehydrogenase, and also citrate synthase. Acetyl-coA inhibits pyruvate dehydrogenase, while succinylCoA inhibits alpha-ketoglutarate dehydrogenase and citrate synthase.
Calcium is used as a regulator, activates pyruvate dehydrogenase, and also activates isocitrate
dehydrogenase and alfaketoglutarate dehydrogenase.
11.
Anaplerotic reaction of citric acid cycle (biochemical importance).
Amphibolic character - involve catabolic and anabolic processes.
Importance - biosynthesis, form intermediates for the Krebs cycle
pyruvate -> oxaloacetate
aspartate -> oxaloacetate (in AST)
glutamate -> alphaketoglutarate (in ALT AST)
beta oxidation of FA -> acetylCoA
adenylsuccinate -> fumarate (adenylsuccinate lyase)
12.
Importance of acetyl-CoA in intermediary metabolism. Metabolic pathways of pyruvic acid –
enzymes, importance.
AcetylCoA from: pyruvate (from glucose), aa (proteins), fa (betaoxi, TAG), ketone bodies (fa). Goes to
citrate cycle (co2, h2o, atp), synthesis of FA, ketone bodies, cholesterol. (not synth of glucose!!)
Pyruvate from: aerobic glycolysis, oxidation of lactate (LD) and degradation of aa, change into acetylCoA,
lactate (lactate dehydrogenase), alanine (ALA), oxaloacetate (pyruvate carboxylase), glucose
(gluconeogenesis).
13.
Conversions of glucose-6-phosphate – its roles in intermediary metabolism
GAG synth glu-6-p - glu-1p - UDPglu - UDPglucuronate - GAG/ascorbate
Gluconeogenesis pyruvate (pyruvate carboxylase) oxaloacetate (pep carboxylase) pep (enolase) 2pg (pg
mutase) 3pg (pg kinase) 1,3-bis pg (glyceraldehyde-3p dehydrogenase) glyceraldehyde-3-p (aldolase)
fructo-1,6-bisp (phosphofructokinase) fructose-6-p (phosphohexose isomerase) glu-6-p, H2O
(hexokinase) glucose, Pi
Glycogenolysis glycogen (glycogenphosphorylase) glu-1p (phosphoglucomutase) glu-6-p (glycolysis)
pyruvate (pyruvate dehydrogenase) acetyCoA - CO2
Glycogenesis glu (hexokinase) glu-6-p (phophoglucomutase) glu-1-p (UDPglycophophorylase)
UDPglucose (glycogen synthase) glycogen
Glycolysis glucose (hexokinase) glu-6-p (fructokinase isomerase) fructose-6-p (phosphofructokinase)
fructose-1,6-bisP (aldolase) dihydroxyacetone-p + glyceraldehyde-3-p (glyceraldehyde-3-p dehydrogenase)
1,3-bisphosphoglycerate (pg kinase) 3-pg (pg mutase) 2-p-glycerate (enolase) pep (pyruvate kinase)
pyruvate (lactate dehydrogenase) lactate
Pentose phosphate pathway glu-6-p (glu-6-p dehydrogenase) 6-phosphogluconolactone
(gluconolactonase) 6-pgluconate (6-pgluconate dehydrogenase) ribulose-5-p (ribose-5-p isomerase)
ribose-5-p + xylulose-5-p (transketolase) glyceraldehyde-3p + sedoheptulose-7-p (transaldolase) fructose-6p + erythrose-4-p. erythrose-4p + xylulose-5-p (transketolase) glyceraldehyde-3-p + fructose-6-p glycolysis
14.
Glycolysis - regulation and energetic balance
Glycolysis glucose (hexokinase) glu-6-p (fructokinase isomerase) fructose-6-p (phosphofructokinase)
fructose-1,6-bisP (aldolase) dihydroxyacetone-p + glyceraldehyde-3-p (glyceraldehyde-3-p dehydrogenase)
1,3-bisphosphoglycerate (pg kinase) 3-pg (pg mutase) 2-p-glycerate (enolase) pep (pyruvate kinase)
pyruvate (lactate dehydrogenase) lactate
Energetic balance - 2 ATP per glucose, 4-6 ATP from the transfer NADH to mitochondria for oxidation.
15. Gluconeogenesis and its regulation
Gluconeogenesis pyruvate (pyruvate carboxylase) oxaloacetate (pep carboxylase) pep (enolase) 2pg
(pg mutase) 3pg (pg kinase) 1,3-bis pg (glyceraldehyde-3p dehydrogenase) glyceraldehyde-3-p
(aldolase) fructo-1,6-bisp (phosphofructokinase) fructose-6-p (phosphohexose isomerase) glu-6-p, H2O
(hexokinase) glucose, Pi
16. Cori and glucose - alanine cycle – the gist, basic roles
Cori cycle: deposition of glucose in the muscles as glycogen, glycogenolysis during muscular activity,
glucose as a source of energy
Glucose-alanine: glucose -> pyruvate -> alanine (alanine from muscle is transported to the liver)
When muscles degradate AA for energy, nitrogen is transmitted to pyruvate to form alanine. Alanine is
transported to the liver where nitrogen enters urea cycle and pyruvate is used to make glucose
17.
Pentose cycle – biological and biochemical importance, regulation
Importance NADPH production, convert hexoses into
pentoses (ATP, CoA, NADP, FAD, RNA, DNA)
Regulation Glucose-6-phosphate dehydrogenase is the
rate-controlling enzyme of this pathway. It is allosterically
stimulated by NADP+ and strongly inhibited by NADPH.
Pentose phosphate pathway
glu-6-p (irreverse, glu-6-p dehydro; nadp-nadph) 6-pgluconolactone (gluconolactonase; h2o-h+) 6-Pgluconate (irreverse, 6-p-gluconate dehy; nadp-nadph,
co2)
ribulose-5-p (ribulose-5-p iso) ribose-5-p / (epimerase)
xylulose-5-p-3epimerase
ribose-5-p + xylulose-5p (transketolase)
glyceraldehyde-3-p + sedoheptulose-7p
(transaldolase) fru-6-p + erythrose-4-p
erythrose-4-p + xylulose-5-p (transketolase)
glyceraldehyde-3-p + fru-6-p
18.
Synthesis and degradation of glycogen, regulation, disorders
glycogen (glycogen-p-rylase) glu-1-p (p-glucomutase) glu-6-p (glycolysis) pyruvate -> acetylCoA
glucose (hexokinase) glu-6-p (p-glucomutase) glu-1-p (udp-glycophosphorylase) udp-glucose (glycogen
synth) glycogen
glycogenin initiates glycogen synthesis, is an enzyme that catalyzes attachment of a glucose to one of it’s
own tyrosine residues. catalyzes glucosylation at c4 of the attached glucose
regulation - epinephrine, glucagon (glycogen degradation), insulin (glycogen synthesis)
disorders - glycogenosis (disorder of glycogen synthesis or breakdown within the muscles), GLUT2
defficiency (accumulation of glycogen in the liver/kidney), aldolase A deficiency
19. Metabolism of monosaccharides (e.g. galactose, mannose, fructose), its derivatives (e.g.
glucuronic acid, aminosaccharides) and its importance in organism
galactose (galactokinase) galactose-1-P (udp-uridyltransferase; udp-glucose->udp-galactose) glucose-1-P
(p-glucomutase) glu-6-P
glucose (hexokinase) glu-6-p (phosphoglucomutase) glu-1-p (udp-glucophosphorylase) UDP-glu (glycogen
synthetase) glycogen
mannose + atp (hexokinase) mannose-6-p (mannose-p isomerase) fructose-6-p (p-glu isomerase) glu-6pfructose + atp (hexokinase) fru-6-p
Glucuronic acid is a sugar acid derived from glucose, with its sixth carbon atom oxidized to a carboxylic
acid. In living beings, this primary oxidation occurs with UDP-α-D-glucose (UDPG), not with the free sugar.
Aminosacharides - hydroxyl group repalced with an amine group; example GLYCALS cyclic derivatives of
monosacharides, can be converted into aminosacharides by nitration (thiophenol).
20.
Biosynthesis and degradation of oligosaccharides, disorders
Sacharide polymer containing small number of simple sugars (monosacharides), Function- cell recognision
and cell binding. Can be O or N-linked, O- attached to threonine or serine on the alcohol group of the side
chain; N- attached to asparagine by beta linkage to amine nitrogen of the side chain.
Example - glycoprotein, glycolipid.
Biosynthesis - preparation of the glycosyl donors, preparation of the glycosyl acceptors with a single
unprotected hydroxyl group, coupling of them and the deprotection process.
21.
Oxidation of fatty acids, energetic balance, carnitine system
Carnitine system - transport acyl group over mitochondrial inner membrane, it’s needed for oxidation of long
chain FA.
Each cycle of oxidation = 1CoA (10atp), 1 NADH2 (2,5 atp), 1 FADH2 (1,5 atp)
acylCoA (dehydrogenase; fad-fadh2) trans-enoylCoA (hydratase) 3-hydroxyacylCoA (dehydrogenase;
nad-nadh) 3-ketoacylCoA (acylCoA acetyl transferase) acylCoA + acetylCoA
22.
Biosynthesis of fatty acids, regulation, disorders
acyl-ACP + malonyl-ACP (3-oxobutanoate synthetase) 3-oxobutanoate (3-ketoacylACP reductase; nadphnadp) 3-hydroxybutanoate (3-ketoacylACP dehydratase) trans-2-butanoate (enoylACP reductase)
butanoate x6 C16; x7 C18
Regulation - by phosphorylation and allosteric regulation.
Allosteric - feedback inhibition by palmitoyl-CoA and activation by citrate. High amount of palmitoyl-CoA the
final product of saturated FA, it allosterically inactivates acecylCoA carboxylase to prevent a biuld-up of FA in
cells. (acetylCoA -acetyl carboxylase- malonylCoA <- inactivation)
Insulin cause the dephosphorylation of acetyl CoA carboxylase thus promoting formation of malonylCoA from
acetyl-CoA, consequently conversion of carbohydrates into FA, while epinephrine and glucagon cause
phosphorylation of this enzyme, inhibiting lipogenesis in favor of FA oxidation by beta-oxidation.
Disorders - extreme sleepiness, behavior changes, poor apetite, vomiting, diarrhea, hypoglycemia, heart
failure, muscle weaknes.
23.
Biosynthesis and degradation of triacylglycerols
TAG -> FA, monoacylglycerol, diacylglycerol (TAG lipase)
TAG -> glycerol -> glycerol-3-p -> dihydroxyacetone-p / TAG synthesis
FA stored in adipocytes of adipose tissue in form of neutral triacylglecerols TAG (form in which we store
reduced C or energy). Releasing FA from neutral triacyglycerols is stimulated by Hormone-sensitive lipase
HSL that is activated by interrelated cascade.
HLS regulation / interrelated cascade - glucagon + epinephrine (inhibition of synth), corticotropin + insulin
(stimulation of synth)
HIGH LEVEL of insulin and glucose HSL is dephosphorylated and becomes INACTIVE
24.
Biosynthesis and degradation of phospholipids, glycolipids and sphingolipids
Phospholipid synthesized from phosphatidic acid (from glycerol-3-p) and 1,2-diacylglycerol (intermediates
in the production of TAG). In the smooth endoplasmic reticulum and inner mitochondrial membrane.
Example: lecithin (phosphoric acid with choline, glycerol, or other fa)
Degradation - phospholipase (A, C, D) cleaves acyl chain of phospholipid -> lysophospholipid
Glycolipids - lipids with a carbonhydrate attached by a glycosidic bond; on the outer surface of all eu cell
membranes; they extend from the phospholipid biley into the aquenous enviroment outside of the cell where
acts as a recognision site for specific chemicals.
Synthesis - depend on the activity of glycosyltransferases responsible for catalyzing the reaction of the
covalent bond formation linking the carbonhydrate complex to the lipid molecule.
Degradation - glycoside hydrolases catalyze the breakage of glycosidic bonds; the lipids and
carbonhydrates will then assume their common uses as energy in the body.
Sphingolipids - class of lipids containing sphingoid bases (aliphatic aminoalcohols included sphinosine);
discovered in brain; play important role in signal transmission and cell recognision.
Sphingolipid with an R group consisting of a hydrogen atom (ceramide), other R group include
phosphocholine, sphingomyelin, cerebrosides and globosides (cerebro+globo= glycosphingolipids).
Synthesis - palmitoylCoA + serine (serine palmitoyltransferase); ceramide phosphorylation of ceramide
kinase to form ceramide-1-p OR glycosylation by glucosylceramide synthase. Sphingomyelin ceramide +
phosphorylcholine by sphingomyelin synthase.
Degradation - ceramide may be broken down by ceramidase to form sphingosine; sphingosine may be
phosphorylated to form sphingosine-1-p (dephosphorylation to reform sphingosine).
Breakdown pathways allow the reversion of these metabolites to ceramide.
glycosphingolipids (hydrolysis) glucosylceramide + galactosylceramide (hydrolysis by beta-glucosidases and
beta-galactosidases) ceramide
sphingomyelin - sphingomyelinase - ceramide (sphinogine+fa)
25. Biosynthesis and degradation of eicosanoids, cyclooxygenase and lipooxygenase pathways
Eicosanoids = Prostaglandins, prostacyclins, thromboxanes,
leukotriens. Local hormones, effects on target cells close to their
site of formation, they’re rapidly degradated so they are not
transported to distal sites of the body.
Cycloxygenase pathway:
injury -> membrane phospholipids -> arachidonic acid -> COX 1
(cytoprotective prostaglandins formation), COX 2 (inflammatory
prostaglandins formation; prostaglandins, prostacyclins,
thromboxanes)
Lipoxygenase - catalyze the first step of the linear pathway for
synthesis of leukotriens.
Leukotriens have roles in inflammation, atherosclerosis,
asthmatic constriction of the bronchioles. 5-Lipoxygenase
catalyzes conversion of arachidonic acid to 5-HPETE which is
converted into leukotriens.
Function: inflamation, fever, regulation of blood pressure, blood
clotting, regulation of sleep and wake cycle.
26.
Formation and utilisation of ketone bodies, metabolic causalities and importance
Ketone bodies - occurs in the heart, brain and muscles (not in the liver); produce by breakdown of fatty
acids, this process supplies E to organs under circumstances such as fasting or starvation. Unsufficient
ketogenesis can cause hypoglycemia and excessive production of ketone bodies leads to dangerous state
as ketoacidosis (high C of ketone bodies, breakdown of FA and deamination of AA).
Function - make available energy that is stored as FA
Production - in the mitochondria of liver cells; in response to low C of glucose in the blood (fasting).
FA (beta-oxidation) acetylCoA (thiolase) acetoacetylCoA (HMG-CoA synthetase) HMG-CoA (HMG-CoA
lyase) acetoacetate -> acetone + beta-hydroxybutyrate
Acetoacetate (decarboxylation) hydroxyacetone (propylene glycol) pyruvate -> lactate -> acetate
Utilization - in the liver by extrahepatic tissues; excretion in urine is very low and undetectable by routine
urine tests;
beta-hydroxybutyrate (dehydrogenase) acetoacetate (beta-ketoacylCoA transferase) acetoacetylCoA
(beta-ketothiolase) acetylCoA + acetyl CoA / acetoacetate -> acetone -> acetol
27.
Biosynthesis of cholesterol and its regulation, biological importance, transport of endo/exogenic cholesterol, disorders
Cholesterol biosynthesis; 3 stages (acetylcoa, mevalonate, dimetylalypyro-p)
acetylCoA + acetoacetylCoA (hmg-CoA synth) hmg-CoA (hmg-CoA red) mevalonate (2atp-2adp) 5-pyro-pmevalonate (atp-adp, pi, co2) isopentylpyro-p - dimetylalypyro-p - geramyl-p - farnesylpyro-p - sqalene - cholesterol
Regulation - HMG-CoA reducase is rate limiting integral protein, statins. Inhibition of cholesterol synthesis reduces
intracellular cholesterol pool and up-regulates LDL-receptors.
Types of regulation - short term, long term (proteolysis, transcription).
Short term - HMG-CoA reductaseis inhibited by phosphorylation catalyzed by AMP-dependent protein kinase.
Long term - formation and degradation of HMGcoA reductase.
a) Regulated proteolysis of HMG-CoA Reductase:
• Degradation of HMG-CoA Reductase is stimulated by cholesterol, oxidized derivatives of cholesterol, mevalonate, &
farnesol (dephosphorylated farnesyl pyrophosphate).
• HMG-CoA Reductase includes a transmembrane sterolsensing domain that has a role in activating degradation of the
enzyme via the proteasome (proteasome to be discussed later).
b) Regulated transcription:
• A family of transcription factors designated SREBP (sterol regulatory element binding proteins) regulate synthesis of
cholesterol and fatty acids.
Of these, SREBP-2 mainly regulates cholesterol synthesis. (SREBP-1c mainly regulates fatty acid synthesis.)
• When sterol levels are low, SREBP-2 is released by cleavage of a membrane-bound precursor protein.
• SREBP-2 activates transcription of genes for HMG-CoA Reductase and other enzymes of the pathway for cholesterol
synthesis.
????
28.
Conversions and elimination of cholesterol, cholic acids, defects in metabolism
Cholesterol is oxidized by the liver into a variety of bile acids (cholic acids). Cholic acids are conjugated
with glycine, taurine, glucuronic acid, or sulfate. A mixture of conjugated and nonconjugated bile acids,
along with cholesterol itself, is excreted from the liver into the bile. Approximately 95% of the bile acids are
reabsorbed from the intestines, and the remainder are lost in the feces. Hypocholesterolemia low level of
cholesterol (cancer, depression), cereberal diseases, hyperthyroidism.
29.
Biological function, composition, synthesis and degradation of chylomicrons, VLDL,
LDL and HDL, disorders in metabolism of lipoproteins
Lipoproteins = chylomicrons, VLDL, LDL, HDL; transport lipids absorbed from the intestine to adipose
cardia and skeletal muscle tissue. (transport also cholesterol)
- Structure - core consisting of a droplet of TAG na cholesteryl esters; surface monolayer of phospholipid,
cholesterol and proteins apolipoproteins.
- Composition - triglyceride, cholesterol esters, phospholipids, free cholesterol, proteins.
- Formation - intestinal epithelial cells synthetize TAG, cholesteryl esters, phopspholipids, free cholesterol
and apoproteins and package them into chylomicrons. Chylomicrons are secreted and by lympahtic
system gets into the blood.
- HDL - secreted by liver
- Degradation - lipoprotein lipase catalyzes hydrolytic cleavage of fatty acids from TAG of chylomicrons,
they are used as a energy sources. Chylomicrons remnants are taken up by liver, than secrete into the
blood VLDL.
- Disorders - familiar hypercholesterolemia (lack of functional LDL receptors, increasing circulating LDL),
atherosclerosis, familial defective apoprotein B100 (impaired LDL binding to cell surface, increase
circulating LDL)
30.
General mechanisms of amino acids degradation, deamination, transamination,
nitrogen balance
Nitrogen balance is a measure of nitrogen input minus
nitrogen output.
31.
Glucogenic and ketogenic amino acids – roles in intermediary metabolism
GLUCO met. to alfaketoglutarate, pyruvate, oxaloacetate, fumarate, succinylCoA
Ala ch3, Asn ch2-c(nh2)=o, Asp ch2-c(oh)=o, Arg ch2-ch2-ch2-nh-c(nh2)=nh
Cys ch2-sh, His ch2 pierscien nh+n, Gly nh2-ch2-cooh, Gln ch2-ch2-c(nh2)=o, Glu ch2-ch2-c(oh)=o
Met ch2-ch2-s-ch3, Pro pierscien z ch2-ch2-ch2, Ser ch2-oh, Val ch(ch3)2
KETO (met to acetylCoA, acetoacetateCoA) Leu ch2-ch-(ch3)2, Lys ch2-ch2-ch2-ch2-nh2
BOTH Ile ch(ch3)-ch2-ch3, Phe ch2-benzen, Trp, Tyr ch2-benzen-oh, Thr ch(oh)-ch3
32.
Ammonia formation in organism and its fate.
Transport and detoxication of ammonia.
Ureosynthesis (cycle of urea formation) –
importance, disorders
Formation from glutamine, glutamate, amino acids,
intestinal bacterial flora or from purine/pirymidine
nitrogenous bases.
Urea cycle disorder it’s deficiency one of six enzymes
which are responsible for removing amonia from the
body. In this disorder amonia is accumulated hyperammonemia (elevated blood amonia). By this way
ammonia goes via blood into the brain and causes
irreversible brain damages.
33.
Metabolism of amino acids group of pyruvate and oxaloacetate (synthesis,
degradation, disorders), involvement of these amino acids to metabolic processes
pyr = Gly Ala Ser Thr Cys Trp*; oxalo = Asp Asn
Glycine - from Serine
Alanine - from pyruvate aminotransferase
3-p-glycerate -> Serine -> Glycine
Threonine - from P-homoserine (Asp)
Cysteine - from Cystathioine
Tryptophan - from Chorismate
Aspartate - from oxaloacetate
Asparagine - from Aspartate
Oxaloacetate -> Aspartate -> Asparagine
Degaradation - glycine, alanine, threonine, cysteine, tryptophan - pyruvate; aspartate - fumarate,
asparagine - oxaloacetate
Glucogenic - can be converted into glucose by gluconeogenesis
Ketogenic - can be converted into ketone bodies
34.
Metabolism of amino acids containing sulphur (synthesis, degradation, disorders),
involvement of these amino acids to metabolic processes
oxaloacetate -> homoserine -> methionine (SAM) homocysteine + serine -> cystathionine -> cysteine +
alfaketoglutarate
cysteine -> hypotaurine -> taurine
methionine - SAM - s-adenosylhomocysteine - homocysteine - cystathione - alfaketobutyrate - propionylCoA
- succinylCoA
Methionine is an essential amino acid, obtained by dietary intake while cysteine is non-essential and a
metabolite of methionine metabolism. Cellular pool of organic sulfur and it’s homeostasis as well as playing a
significant role in regulation of one carbon metabolism. Genetic defects in the enzymes.
Disorders: homo- and cystinuria, homo- and cysteinemia, and neural tube defects. Thiol imbalance has
been associated with multiple disorders, including vascular disease, Alzheimer's, HIV and cancer.
35.
Metabolism of amino acids group of 2-oxoglutarate and succinyl-CoA (synthesis,
degradation, disorders), involvement of these amino acids to metabolic processes
alphaketoglutarate - produced by glutamine (glutamate, gaba synth), glutamate (gaba synth), proline,
arginine (ceratinine synth), histadine (histamine synth)
degradation in the citric acid cycle, joining by alphaketoglutarate
succinylCoa - is produced by isoleucine, valine, methionine; succinylCoA synthesizes porphiryns (in action
with glycine) example : heme.
36.
Metabolism of aromatic and
branched amino acids (synthesis,
degradation, disorders) involvement
of these amino acids to metabolic
processes
CHORISMATE - Tyrosine - Phe
CHORISMATE - Tryptophan
37.
Biosynthesis, biodegradation and function of biogenic amines and polyamines
Biogenic amines - one/more amine groups, formes by decarboxylation of aa or amination and
transamination of aldehydes and ketones.
Monoamines - histamine (from histidine) neurotrasmitter, released from mast cells in response to allergic
reaction or tissue damage, HCl stimulation in stomach. Serotonin CNS neurotransmitter synth from
tryptophan.
Catecholamines - norepinepgrine, epinephrine, dopamine (synth from tyrosine)
Polyamines - two/more amino groups; putrescine, cadaverine, spermidine, spermine. Diet and denovo
synthesis. Regulate by ODC ornithine decarboxylase. High concentration in mammalian brain. Are important
chelating agents DETA/TETA (bonding of ions and molecules to metal ions, coordinate bonds.
Putrescine from arginine, Cadaverine from lysine, Spermidine from putrescine, Spermine from spermidine
with SAM.
??? 38.Biosynthesis and degradation of tetrapyrrols, regulation, disorders
Tetrapyrroles - four pyrrole rings held together by covalent bond or carbn bridges, have linear or cyclic
fashion. Example: hemoglobin, chlorophyll, cobalamin.
Heme breakdown - bilirubin, biliverdin.
Heme synthesis - ALA formation
ALA - uroporphyrinogen III - protoporphyrin IX - HEME / chlorophyllide a/b -> CHLOROPHYLL a or b
39.
Biosynthesis and degradation of pyrimidine nucleotides – chemism, importance, regulation,
disorders
Glutamine (atp h2o ->glutamate) carbamoyl-P -> aspartate + carbamoyl-P -> Dihydroxoorotate -> orotate ->
OMP -> UMP
UTP + ATP (glutamine - glutamate; CTP synthetase) CTP + ADP
degradation products: beta-alanine, beta-aminoisobutyrate, carnosine, anserine
cytosine - uracil - beta alanine - carnosine anserine
5-methylcytosine - thymine - beta amino isobutyrate
disorders - immunodeficiency, orotic aciduria (orotidylic acid), miller syndrome, dihydropyrimidine
dehydrogenase deficiency
40.
Biosynthesis and degradation of purine nucleotides – chemism, importance, regulation,
disorders, salvage reactions
Ribose-5-P (PRPP) 5-P-ribosylamine (de novo) IMP (adenylsuccinate synth) adenylsuccinate
(adenylsuccinate lyase) AMP -> ATP
IMP (dehydro) XMP (GMP synth) GMP -> GTP
degradation: amp - imp / adenosine - inosine - hypoxantine (adenine) - xantine (guanine) - uric acid allantoin
disorders- lesch nyhan syndrome, gout, xanturia (xanthine oxidase disorder)
Salvage pathways are used to recover bases and nucleosides that are formed during degradation of RNA
and DNA. This is important in some organs because some tissues cannot undergo de novo synthesis.
PRPP enzyme is required for this reaction. hypohanthine + guanine (PRPP) HGPRT reaction (saving)
II. The molecular biochemistry and organ biochemistry
1.
Compartmentalization of biochemical processes on cellular level.
All reactions occurring in cells take place in certain space – compartment, which is separated from other compartments
by semipermeable membranes. They help to separate chemically quite heterogeneous environments and so
to optimise the course of chemical reactions.
Enzymes catalysing individual reactions often have different temperature and pH optimums and if there was only one
cellular compartment a portion of enzymes would probably not function or them-catalysed reactions would not
be sufficiently efficient. By dividing the cellular space, optimal conditions for individual enzymatically catalysed
reactions are created.
The width of a cell membrane is approximately 6-10 nm. The core of its architecture is made of phospholipid bilayer with
embedded proteins and cholesterol molecules. The latter two can bind various saccharides and so form
glycolipids and glycoproteins. This basic structure is, in the case of membranes of different organelles, modified
to a certain degree, thus affecting the physico-chemical properties of the membrane (especially its
permeability), which are in close connection to the function and course of the biochemical processes in the
organelle.
2.
Structure, composition and properties of cell membranes. Transport of substances through the
membrane
Fluid mossaic structure. Cholesterol = fluidity.
Passive transport (oxygen), diffusion (ions), faciliated
diffusion with carrier proteins (glucose), active
transport with ATP against gradient.
Proteins - integral, peripheral, surface protein,
glycoprotein.
Functions: receptors, transport, enzymes, cell adhesion
3. Structure and function of nucleic acids. Genetic
code and its properties
The genetic code - set of rules by which information
encoded on mRNA sequences is translated
into proteins. Decoding by the ribosome, which
links amino acids in an order specified by
mRNA, using tRNA to carry aa.
Properties triplet codons code one aa, degenerate
(more than one triplet code many of the aa),
61 triplets (uaa uag uga stop codons),
universal for all organisms; non overlapping,
encode polypeptide chain, comma less
4. Organisation of prokaryotic, eukaryotic and mitochondrial genome. Human genome, technics
of DNA sequencing
Prokaryota - no nucleus, genome held within a DNA/protein complex in the cytosol - nucleoid - which lacks a nuclear
envelope. Contains single, cyclic, double stranded molecule of chromosomal DNA. Replication transcription and
translation in cytosol.
Eukaryota - membrane bound nucleus; linear DNA contained chromosomes; have circular mitochondrial genomes.
Replication and transcription in nucleus, translation in cytoplasm.
Organization (eu) - dna, histone, linked histones, chromatosomes, folded fibers, chromatid, chromosome.
PCR polymerase chain reaction, dentaturaion-anneling-elongation. Method used during clonning, invitro fertilization, or
during searching of human genetic diseases.
5. Replication of DNA in eukaryotic and prokaryotic cells, regulation, inhibition. Reparations of
DNA, significance, limitations
helicase - helix destabiling enzyme, unwinds dna double helix at replication fork
primase - provides start point of rna/dna for dna polymerase to synth new dna strand
topoisomerase - relax - and + supercoils, I topo by one cut, II topo by two cuts
ligase - seals gaps between okazaki fragments with phosphodiester bonds
eu poly alpha- synth laging strand, beta- repair, gamma- synth of mito gen mat, delta and epsilon- proofreading
pro poly I - veryfication, synth p-diester bonds, II- correction, III- synthesis of bonds
repair mechanism:
- mismatch - strand cutting, copying error 1-5 bases unpaired, exonuclease digestion, dna scan and find nick in new dna
strand then strand removal and repari dna synth
- nucleotide excission - 30 bases remove, correct added, uvr nuclease, dna poly I, dna ligase
- base excission- new base added, failure removed by n-glycosylase (dna glycosylase, apyrinidinic endonuclease, dna
poly I, dna ligase
-double strand break- unwinding
=> xeroderma pigmentosis- low enzymatic activity for nucleotide repairing proces, thymine dimer form this disease
inhibitors: (antibact) ciprofloxacin, nalidix acid, novobiocin, (anticancer) etoposide human topoisomerase, doxorubicin
human topo, 6-mercaptopurine(polymerase), 5-fluorouracil (thymidylate synthase)
6.
Transcription of DNA. Regulation of gene expression on the level of transcription, inhibitors
DNA -> mRNA
- sigma factor binds to RNA polymerase holoenzyme allowing bind to promoter DNA (eu: tatabox, pro: prinbow box)
- RNA polymerase creates transcription buble, which separates two strands of DNA helix
- polymerase adds matching RNA nucleotides to the complementary nucleitides of DNA strand
- hydrogen bonds of the untwisted RNA-DNA helix break, freeing the newly synthesized RNA strand
- > polyadenylation, capping enzyme, splicing
polynucleotide kinase- 5’ end phosphorylation
RNA ligase- exon join
phosphatase- 2-phosphate removing
inhibitors: actinomycin D (from streptomycin, insertion of phenoxazone between two GC), rifampicin (from rifamycin,
bind beta subunit of rna poly), alpha amanitin (toxin from mushroom turn off rna poly II), 3’-deoxyadenosine (synthetic,
incorrect entry into chain causing chain termination)
-transcriptional regulation – help rna polymerase binding to dna
-promoter – a region of DNA that initiates transcription of a particular gene
-sigma factor (holoenzyme) – bact. co-factor that complex with rna polymerase, encode sequence specificity
-coactivator – protein that works with transcription factors to increase rate of gene transcription
-corepressor – protein that works with transcription factors to decrease rate of gene transcription
-lac operon- genes resp for lactose metab, bind to represor+operator region to controll expresion
-represor- transcription factor, inhibits gene expression, binds to operator
7. Specifications of biosynthesis of mRNA, rRNA and tRNA
- mRNA transcription;
- rRNA two subunits; 60s 40s;
E-site exit site only large subunit - realising the deacylated trna
P-site peptidyl large and small - forming peptidyl bonds
A-site aminoacyl large and small- accepting aminoacyl trna by aminoacyl trna synthetase
- tRNA trna- 3’oh acceptor arm, twcg loop, anticodon loop, d loop, 5’ P
8. Proteosynthesis in prokaryotic, eukaryotic cells and in mitochondria. Inhibition of
Transcirption; Translation
EU = monocistronic (coding sequence only for one polypeptide), cytoplasm, introns and exons, splicing, capping 5’, polyA-tail, start codon methionine
PRO = polycistronic (coding sequence of several genes), cytoplasm, only exons, no splicing, no capping, no poly-A-tail,
start codon formyl-methionine
Mitochondria - only small amount of proteins can be synthetize,
Exogenic inhibitors - antibiotics, toxins (ricins), neomycin, geneticin, rifamycin, tetracyclines, aminoglycosides
9.
Posttranslational modifications of proteins. Protein folding and chaperones – post synthetic
processes
Posttranslational modification - disulfide bridges, glycosylation, phosphorylation, acetylation; amino terminal
modification; proteolytic cleavage (digestive enzymes, hormones)
Chaperon - folding or stabilizing protein; production of recombinant proteins to treatment of protein misfolding in vivo.
10.
Genetic manipulation (e.g. restriction endonucleases, cloning, PCR, gene therapy)
Restriction endonucleases - enzymes that cut DNA near the restriction sites (nucleotide sequences). Two cuts - sugar
phosphate backbone. In bacteria and archaea, provide a defense mechanism against viruses. 5 types + artificial
restriction enzymes. Used in recombinant DNA technology.
Cloning - process of producing similar populations of genetically identical individuals. Creating copies of DNA fragments,
cells or organisms.
PCR polymerase chain reaction, dentaturaion-anneling-elongation. Method used during clonning, invitro fertilization, or
during searching of human genetic diseases.
Gene therapy - therapeutic delivery of nucleic acid polymer into a patient’s calls as a drug to treat disease. Example:
vaccination. In this method necessary is using vectors (viruses) as deliver of DNA into the cell.
11.
Inhibitors of biosynthesis of nucleic acids
Antibiotics - rifamycin, quinolones, antifolates, norfloxacin, levofloxacin, doxorubicin.
12.
Membrane receptors and their ligands, G-proteins
Receptors at the surface of a cell that act in cell signaling by receiving extracellular molecules; they are specialized
integral membrane proteins such as - hormones, neurotransmitters, cytokines, growth factors, nutrients.
Ligands affects a cascading chemical change through the cell membrane during signal transduction.
G-protein involved in transmission of signals from a variety of stimuli ouside a cell to its interior. Regulated by factors
that control their ability to bind and hydrolyze GTP to GDP. When bind to GTP they are ON, when GDP they are
OFF.
13.
Types and roles of second messengers
Second messanger intracellular signaling molecule realased by the cell to trigger physiological changes such as
proliferation, differentiation, migration and apoptosis.
Function - transmit signals from receptor to a target.
Examples - cAMP, cGMP, calcium, DAG.
Second messanger is realases in response to extracellular messanger - first messanger (neurotransmitters,
epinephrine, growth hormone, serotonin).
1. Hydrophilic - cAMP, cGMP, Ca2+, NO, CO, H2S
2. Hydrophobic - DAG, PIP, PIP2, PIP3
14.
The role of Ca
2+
and phospholipases in hormone action
calcium most extracelular, intra in muscle cells, 2.2-2.6 mmol/l
forms: diffusible: ionized 50%, complex 10%(citrate, phosphate); nondiffusible: prot bound ca 40%(bound to negat.
charged albumin)
absorption: 1st+2nd part of duodeum, absorb against conctr gradient, needs E and carier prot
incr by: vitD (calcitrol- induces synth of calbindin carier prot), parathormone (bind with surface receptor of target cel,
sites of action: bone,kidney,intestine), acidity (incr abs), aa (lys and arg incr abs)
dec by: phytic acid (hexaP of inositol in cereals), oxalates(leafy vegetable), malabsorption syndrome(fa not abs,
formation of insoluble ca salts of fa), phosphate(hi content, precipitation calciumP), calcitonin(inhi resorb of bone and
osteoclasts)
function: activation enzymes, exitation and contraction of muscle fibers, nerve conduction, second mesanger, secretion
of hormones, coagulation factor IV
vitD- stimulate osteoblasts to secrete phosphatase, incr secretion of Klotho prot form kidney
PTH- secrete by 4 parathyroid glands, synth by preproPTH with 115 aa, broke into pth with 84 aa, storage about 1h, incr
Ca then secretion of calcitronin
hypercalcemia 2.75mmol/l and more, due to parathyroid adenoma, ectopic pth secreting tumor, check by renal calculi,
chronic renal failure, neuro symptoms, irritability
hypocalcemia les than 2.2. deficit of vitD and parathyroid, incr calcitonin and phosphorus level. muscle cramps,
bradycardia, praesthesia
directly activ. of enzymes pancreatic lipase, coagulation pathway, rennin indirect by calmodulin, ca binding prot,
kinase (Ca/calmodulin depentent protein kinase)
15.
Biochemical processes in digestion and absorption of nutrients
Nutrients - aa, fats, sugars, nucleic acid components, minerals, vitamins
Mucosa of the small intestine contains many folds that are covered with villi with microvilli. These structures create
surface through which nutrients can be absorbed; specialized cells allow absorbtion through mucosa into the blood.
At the first time absorbtion of nutrients begins in the small intestine (jejunum, illeum - into blood stream and liver).
Lymphatic system is responsible for the absorption of nutrients.
Carbonhydrates - glucose - glycolysis - glycogen, oxidation for E
Fats - fa, glycerol - beta oxidation - TAG in adipose tissue, cellular membranes, oxidation for E
Proteins - aa - transamination - stored as fat or glycogen, new protein formation, oxidized for energy
-> oxidation for energy -> acetylCoA -> Krebs cycle -> ATP, CO2, H2O
16. / 15 ??? Mutual relation in metabolism of saccharides, lipids and proteins
17.
Conjugated and nonconjugated bilirubin, defects in excretion of bile pigments.
Conjugated with a molecule of glucuronic acid which makes it soluble in water - glucuronidation by glucurotransferase.
Unconjugated unsoluble in the water
Defects - if liver’s function is impaired or when biliary drainage is blocked, some of the conjugated bilirubin leaks out of
the hepatocytes and appears in the urine (dark amber color).
Hemolytic anemia - increased number of red blood cells are broken down, causing increased amount of unconjugated
bilirubin in the blood. Unconjugated bilirubin is not water soluble - not increased level in the urine. Because in this
case is no liver damage or bile system, this excess unconjugated bilirubin will go through all of the normal
processing mechanism and will show up as an increase in urine urobilinogen.
Heme - Biliverdin - Bilirubin (bile duct) - Glucuronic acid removed by bacteria - Urobilinogen - Stercobilin
18.
Vitamins soluble in lipids and in water, importance, function
Vit B1, B2, B3, B5, B6, B7, B9, B12, vit C
Vital nutrient that an organism requires in limited amounts. An chemical compound is called a vitamin when organism
cannot synthetize, must be obtained in diet.
19.
Metabolism of water and its function in living systems. Hormonal regulation of water
and mineral metabolism
Functions - powerful solvent for ionis and neutral molecules, dissociation of macromolecules, cooling of the body by
evaporation in the lung and from the skin;
Routes of water loss - skin, lungs, kidneys, intestine
Distribution of body water is affected by the osmotic forces.
Mineral metabolism - sodium, potassium, chlorine, calcium, magnesium, phosphorus, sulfur.
Regulation - vasopressin (increase water reabsorption in the kidney)
20.
The blood, composition and function – biochemical view
Function - respiratory, nutrition, excretory, regulatory, body T, protective. Composition - water 91%, proteins 7%,
iorganic ions 1%, organic (urea, fats, cholesterol, glucose)
21.
Buffer systems of organism, function and importance for acid-base balance
Chemical and physiological buffers. Bicarbonate, phosphate, protein buffer, respiratory mechanism, renal
mechanism. Biological ph of blood ranges from 7.4-7.8. To mantain a fixed pH organism has available a numner
of mechanism and buffer system. Respiratory acidosis (hi Co2 pressure), resp alkalosis (low Co2 pressure),
metabolic acidosis (low HCO3- in arteries, diarhea), metabolic alkalosis (hi HCO3- in arteries, vomiting).
22.
The proteins of blood plasma, methods of determination and fractionation,
diagnostically importance
7% = albumins, globulins (alpha1, alpha2, beta1, gamma), fibrinogen, enzymes (thrombin, plasmin, AST, ALT,
LDH, AP). Determination - electrophoresis and then spectrophotometer.
23.
Metabolism of erythrocytes
90% anaerobic glycolysis (atp, lactate, cori cycle, 2,3-BPG), 10% hexose monoP pathawy (nadph), glucose-6-p
dehydrogenase, pyruvate kinase, hemolytic anemia
glycolysis in erytho 1,3-BPG (mutase) 2,3-BPG (phosphatase) 3-PG
cori cycle: (liver) lactate -> glucose -> (muscle) glucose -> lactate (glycolysis)
24.
Biochemical mechanism of hem coagulation, the role of thrombocytes
25.
Transport of O2 and CO2 – biochemical mechanisms and disorders
Erythocytes transport oxygen, o2 binds reversibly. Oxyhemoglobin - bound to oxygen, deoxyhemoglobin - after
oxygen diffuses into tissue (reduced), carbaminohemoglobin - bound to carbon dioxide. Heme structure - 4
nitrogen, iron cation 2+ bound by coordination covalent bounds. Hemoglobin autooxidation Hem-Fe2+O2 =
Hem-Fe3+O2
26.
Defects of acid-base balance (e.g. the role of lungs, kidneys)
Respiratory acidosis (hi Co2 pressure), resp alkalosis (low Co2 pressure), metabolic acidosis (low HCO3- in
arteries, diarhea), metabolic alkalosis (hi HCO3- in arteries, vomiting).
27.
Digestion and absorption of saccharides and lipids in GIT, their role in the diet
Sacharides - digestion in the small intestine; hydrolysis to monosacharides before the absorption. Glucose is taken
faster then fructose. Digestion on starch begins in oral cavity by alpha-amylase and by pancreatic amylase in
small intestine (into maltose and maltoriose). Monosacharides are hydrolyzed by maltase, isomaltase, sucrase
or lactase.
Absorption - in small intestine by active diffusion that requires energy. Carbonhydrates not digested in the small
intestine are digested in the large intestine, bacterial flora metabolize these compounds anaerobically production of gasses (methane, hydrogen, carbon dioxide) and short chain fatty acids (acetate, butyrate). FA
are rapidly metabolized - butyrate in colon, acetate into the blood and taken up by the liver and muscles
(important precursor of glucose in animals).
Lipids - Gastro-intestinal lipases (GIT) - pancreatic lipase, phospholipases, cholesterolestrase, lysophospholipase
Degradation
TAG -> FA, monoacylglycerol, diaccylglycerol, by TAG lipase
PL phospholipids -> by pancreatic phospholipase
CHE cholesterol esters -> by pancreatic cholesterylester hydrolase to free cholesterol
Digestion takes place in small intestine. Bile salts break large droplets into smaller. Digestion products are as „mixed
micelles“ absorbed to enterocytes.
FA stored in adipocytes of adipose tissue in form of neutral triacyglycerols (form in which we store reduced C or energy).
Releasing FA from neutral triacyglycerols is stimulated by hormone-sensitive lipase (HSL) that is activated by interrelated
cascade.
HLS regulation / interrelated cascade - glucagon + epinephrine (inhibition of synth), corticotropin + insulin (stimulation of
synth)
HIGH LEVEL of insulin and glucose HSL is dephosphorylated and becomes INACTIVE
Products from HLS action - 3 moles of FA, 1 mole of glycerol
Free FA are transported in the blood by albumin, and transported to other tissues where they diffuse into cells.
Glycerol metabolism
Glycerol can’t be metabolized by adipocytes bacuse lack of GLYCEROL KINASE.
Is transported to the liver via blood and there phosphorylated by GLYCEROL PHOSPHATE
glycerol (glycerol kinase; atp-adp) glycerol phosphate (glycerol-p dehydrogenase; nad-nadh2) dihydroxyacetone-p
- glycerol phosphate - can be use for TAG synthesis in the liver or converted to dihydroxyacetone-p (glycolysis/
gluconegogenesis)
28.
Digestion of proteins in GIT and resorption of cleaved products, the role of proteins in
the diet
PROTEASES and PEPTIDASES split proteins into small peptides and amino acids.
In the stomach pepsin breaks down protein into smaller particles such as peptide fragments and amonoacids.
Protein digestion starts in the stomach. HCl denaturate the proteins (bacteria or viruses that remains in the food)
and also activate pepsinogen and pepsin.
GASTRIN produced by G-cells of the stomach. G-cells produce gastrin after stomach exposure to protein.
TRYPSINOGEN breaks down proteins at the basic amino acids.
CHYMOTRYPSIN once activated by duodenal enterokinase breaks down proteins at their aromatic aminoacids.
CARBOXYPEPTIDASE takes off the terminal aa group from protein
ELASTASES degrade the protein elastin and some other proteins
Products - essential amoni acids taking part in the metabolism (Arg, His, Isoleucine, Leucine, Lys, Met, Phe, Trp,
Val, Thr)
Diet - used to build and repair tissue; need to make enzymes, hormones; important to biuld block of bones,
cartlige, skin and blood. Reduce muscle loss, building lean muscle, helping to maintain a healthy weight, curbing
hunger.
29.
Hormones – chemical structure, importance, disorders
Types of chemical messenger:
- hormones - relased by cells that affect other distant cells in other parts of the body
- eicosanoids - derived from arachidonic acid (prostaglandins, prostacyclins, thromboxanes, leukotriens)
- cytokines - proteins, peptides or glycoproteins (autocrine, paracrine, endocrine)
- chemokines - protein cytokines with 4 Cys residues (chemotactic cytokines)
- lymphokines - cytokines secreted by helper t-cells in response to stimulation by antigen
Hormones - regulatory molecules secreted into the blood or lymph by endocrine glands.
Endorine glands - thyroid, adrenal, pancreas, ovary, testis.
Thyroid hormones (from AA) - contains 4 iodine atoms (T4), 3 iodine atoms (T3), non polar molecules
Peptide pth, angiotensin2, fibroblast grow hormone, adh, insulin
Polypeptides - ADG, Insulin
Glycoproteins - FSH, LH
Steroids - lipophilic hormones, testosterone, estradiol, cortisol, progesterone
Chemical classification of hormones:
- steroid hormones - lipid soluble, diffuse through cell membrane, endorine organs (adrenal cortex, ovaries, testes,
placenta)
- nonsteroid hormones - non lipid soluble, received by receptors external to the cell membrane, endocrine organs
(thyroid gland, parathyroid glands, adrenal medulla, pituitary gland, pancreas)
Receptors for steroid hormones - in cell’s cytoplasm on nucleus
Receptors for nonsteroid hormones - located on cell membrane
Cell surface receptos - integral transmembrane protein with extra and intracellular domain
Transmembrane receptors - G protein, coupled receptos, receptor tyrosine kinase, integrins, pattern recognition
receptors, ligand activated ion channels
Hormone action - taget cell must have specific receptors for hormone, hormone binds to receptors with high bond
strength, low saturation of receptors, hormones of same chemical class have similar mechanism of action
Effects of hormone concentr - if higher can increase number of receptors on target cells, greater response, pulsatile
secretion may prevent downregulation, reflects the rate of secretion
Negative feedback - primary mechanism through which endocrine sys maintains homeostasis, example plasma glucose
levels and insulin response
Number of receptors
- down regulation - decrease sensitivity to that hormone
- up regulation - cell more sensitive to hormone
Regulation of glucose
-glucagon - glycogenolysis, secretion incr during exercise to promote glycogen breakdown
-epinephrine and noreepinephrine - increase glycogenolysis
-cortisol - molibizes free fa
-thyroxine- glucose catabolism
Regulation of fa metabolism during excercise - low plasma glucose stimule catecholamines to relasing and
accelerate lypolysis, triglycerols are reduced to free fa by lipase which is activated by cortisol, epinephrine,
norepinephrine, growth hormone
Hormonal effects on fluid and electrolyte balance - reduced plasma v leads to relase aldosterone that incr Na+ and
H2O reabsorption by kidneys and renal tubes, antidiuretic hormone ADH is relased from posterior pituitary when
dehydratation is sensed by osmoreceptors and water is reabsorbed by kidneys
31.
Biochemistry of liver. The options of biochemical diagnostics of damage of hepatocytes
and liver function
Damage markers: ALT AST
Hypoglycemia - during loss of liver function; glycogenolysis and gluconeogenesis cannot run
Hepatocytes - bilirubin conjugation and excretion, biosynth of albumin, fibrinogen, bile acids, urea, conversion of
steroids
Function - metabolism of nutriens, plasma proteins synthesis, cholesterol and lipoproteins metabolism, detoxification
and excretion of xenobiotic (drugs, carconogens, ethanol), homeostasis, immune mechanism; excretion of substances
with the bile to the intestine
Metabolism - carbonhydrates (glucose, galactose, fructose, mannose, pentose, glycerol, glycogen), lipids (FA, fats,
ketone bodies, cholesterol, bile acids, vitamins), AA, urea, nucleotides, plasma proteins (lipoproteins, albumins,
coagulation fcator, hormones, enzymes)
biosynthesis: glucose, pentose, glycerol, glycogen, fa, fats, ketone bodies, cholesterol, bile acids, urea, nucleotides,
lipoproteins, albumins, coagulation factors, enzymes
conversion and degradation: galactose, glucose, fructose, mannose, pentose, glycerol, glycogen, fa, fats, ketone
bodies, cholesterol, vitamins, aa, nucleotides, lipoproteins, albumin, coagulation factor, hormones, enzymes, steroid
hormones, bile pigments, drugs
excretion: cholesterol, bile acids, steroid hormones, bile pigments, drugs, ethanol
storage: glucose, glycogen
enzymes in xenobiotic metabolism: alcohol dehydrogenase, aldehyde dehydrogenase, aldexyde oxidase, cytochrome
p450 monooxygenase, flavin monooxygenase, monoamine oxidase, xanthine oxidase, esterase
phases: I biotransformation, II conjugation (biotransformation enzymes: udp-glucuronosyltransferase, glutathiones-transferase, sulfotransferase, thiol transferase, acetyltransacetylasae)
32.
Biochemistry of kidney. Clearens, The options of biochemical diagnostics of damage of
nephrons and kidney functions
- function - excretion of urea, na+ k+ h+, balance water amount, prod of erythropoietin, filtrate 180l h2o with ions
sodium chloride sugar and aa; proton secretion, ammonia excretion; excretion of xenobiotics
- metabolism : urea, cretinin, aa, enzymes, carnitine; activation of vit D; Ca and P metabolism
- hormones - angiotensisn II (stimul by decr blood v or p, act by constriction of afferent and efferent arterioles, decr
-
GFR), atrial natruretic peptide (stimul by stretching of arterial walls due to incr blood v, act by relax of mesangial cells
incr filtration surface, incr GFR)
urine - urea, uric acid, creatinine, k, cl, n, prot, hco3-, glu
endocrine function - renin (catalyze angiotensin synthesis), angiotensin (stimulate aldosteron), erythopoietin (bone
marrow formation), prostaglandins (act on blood flow) => angiotensinogen - renin - angiotensin I - angiotensin II
- acid base balance - by regul secretion of h+ which react with bicarbonate before reabsorb, if h+ is low kidney dont
reabs as much bicarbonate (incr amount of bicarb excreation), if h+ is high kidney reabs all bicarbonate and h+ in tubular
lumen combine with phosphate and amonia excrete as salts
- clearance - quantity of blood/plasma completely cleared of substance per unit time and expressed as ml/min, ml of
plasma which contains amount of that substance excreted by kidney in min
- gluconeogenesis - precursor lactate glycerol and fructose; substrate glutamine in proximal tubule; regulated by cortisol
- urea cycle; primarly in the liver and then in the kidney
Q elimination of proton by: urine, bicarbonate , amonium ion, phosphate
Q source of amonia: glutamine, glutamate
Damage checked by renal biomarkers
Diseases - glucosuria, ketonuria, bilirubinuria, creatinuria, phenylketonuria
33.
Biochemistry of nervous tissue, neurotransmitters
Glutamine (glutamate synthetase ;h2o - nh4+) Glutamate (glutamate decarboxylase) GABA + co2 -> succinic aldehyde
-> succinate
Neurosecretion - neurotransmitters, neurohormones
Neurotransmitters - chemical transducers which are released by electrical impulse into the synaptic cleft from
presynaptic membrane from synaptic vesicles. It then diffuse to the postsynaptic membrane and react and activate the
receptors present leading to initiation of new electrical signals. Acetylcholine (most important), aa, biogenic amines,
peptides, purine derivates, CO, NO.
-> hydrophilic - NO, CO, cAMP, cGMP
-> hydrophobic - DAG, PiP, PiP2, PiP3
Substrates - prod by neurons, stored in synapses relase into the synaptic cleft (stimulus), at postsynaptic membrane
Receptors - ionotropic (ligand gated ion chanels), metabotropic (coupled to G proteins)
G proteins - stimulatory or inhibitory, transfer signals from 7-helix receptors
Membrane potential - electrical voltage between two sides of the membrane.
Resting and action potential
1) open na/k voltage gate
2) Sodium flow into the cell, depolarization, voltage dependent K chanels open
3) Sodium chanels close again, so inflow of positives charges is very brief, K flow out, Na/K ATPase pumps na that have
entered back out again, repolarization
4) two processes briefly lead to change, hyperpolarization
Acetylocholine receptors - nicotinic, muscarinic
Metabolism of acetylcholine - acetylCoA + choline in presynaptic axon and stored in synaptic vesicles, damage by
acetylcholinestrase
E sources for brain - ketone bodies (starvation), glucose
Metabolism of CNS - glucose the only metabolite from which brain obtain atp. lipids unable to pass blood brain barier,
aa can but in limited amounts
Ketone bodies - use only by brain and renal cortex
36.
Biochemistry of function of skeletal, heart and smooth muscle. Biochemistry of muscle
contraction. Markers of damage of muscle tissue, importance, determination
Muscles - turn chemical E into mechanical; cardiac (heart, nonvoluntary), smooth (internal organs, nonvoluntary),
skeletal (associated with skeletal system, voluntary, movement of bones)
Sarcomere - functional unit of muscle, from Z to Z line, actin thin filament, myosin thick filament,
Myofibrils - immersed in cytosol, rich in glycogen, atp, creatine phosphate and glycolytic enzymes
Fiber type - fast, intermediate, slow
Protein - thick: myosin, thin: actin, tropomyosin, troponin complex
Contraction - sliding of thick myosin and thin actin filaments
Concentric cross bridge cycle - Ca ion realased from SR, binds to troponin, tropomyosin moves away from binding
site, actin-myosin cross bridge forming, myosin does mechanical work on actin, myosin arm rotates shortening muscle
fiber
Smooth mm contraction - [ca2+] incr when ions enter the cell and realased from sarcoplasmic reticulum, ca2+ binds to
calmodulin than activates myosin light chain kinase MLCK which phosphorylates light chain in myosin heads and incr
myosin ATPase acitivity, active myosin crossbridge slie along actin and create muscle tension
-> epinephrine stimul glycogenolysis in skeletal muscle
-> glucagon doesn’t because lack of receptors
-> insulin act on skeletal muscle to increase uptake of glucose
Smooth mm relaxation - free ca2+ in cytosol decr when ca2+ pumped out of the cell into sarcoplasmic reticulum, ca2+
unbinds from calmodulin, myosin phosphatase removes phosphate from myosin which decr myosin ATPase activity, less
myosin ATPase results in decreased muscle tension
Disorders - muscle cramps (caused by hyperexcitability of somatic motor neuron), musle overuse (muscle fatigue,
trauma may cause tearing the tissue), muscle disuse (muscle atropy, muscle blood supply diminishes and fibers get
smaller), aquired disorders (weaness from infectious diseases-influenza)
Duchenne muscular dystrophy - absence of cytoskeletal protein dystrophin, fibers have tiny tears which allow calcium
ions to enter them and activate enzymes that break down fiber components
Damage marker - CK creatine kinase, lactate dehydrogenase, aldolase, myoglobin, troponin, Asp aminotransferase
37.
Metabolism of xenobiotic – types of biotransformation reactions, their importance, disorders
xenobiotic - foreign compound, no biological value, include drugs, chemical or carcinogens, may be excreted
unchanged ot it may be metabolized by body’s enzymes to other compunds
classification - accidental- inhalation of toxic chemicals from polluted atmosphere; deliberated- when drug enter the
body by injection
principles - acidic, greatest capacity at portals of entrances (lung, skin) and exits (gut, kidney)
toxic because: bind and damage proteins, dna (mutatnions) and lipids, react in the cell with o2 to form free radicals
which damage lipid proteins adn dna; organ defects, mutagenesis, carcinogenesis, death; CNS, immune system, liver,
skin, eye, respiratory system…
metabolism of xenobiotics: in liver by enzymatic process, convertion into more hydrophilic substrates or into cytotox.
muthagenic compounds
Phase I biotransformation -important role in detoxification and activation of org pollutants (cyp450, activated by planar
aromatic hydrocarbons)
-atachment of new functional groups, transformation of functional gr by oxidation reduction hydroxylation hydrolysis
deaminaion dehalogenation desulfuration epoxidation peroxygenation
-enzymes oxidation: oxidoreductases, oxidases, monoamine oxidases, mixed function oxidases
-enzymes reduction: oxidoreductases, reductases
-hydrolysis: estrases, amidases, peptidases, lipases, hydrolases
Phase II conjugation - masking of functional grou[ by acetylation glycosylation or atachment aa, ionic/hydrophilic groups
adding;
-conjugates with glucuronic acid, sulfate, acetate, glutathione, aa, methylation
-function- to make xenobiotic more polar and water soluble, conjugates are less toxic (in few cases toxicity increase)
-biotransformation enzymes: udp-glucuronosyltransferase, glutathione-s-transferase, sulfotransferase, thiol transferase,
acetyltransacetylasae
glucuronidation - most frequent conjugation reaction and takes place in ER; udp-glucuronic acid is glucuronyl donor
and glucuronosyltransferases are catalysts; substrates are alcohols phenols amines sulfides and carboxylic acid
glutathione conjugation: cytosol and ER, subs: metabolites of arachidonic acid (leucotriens)
enzymes in xenobiotic metabolism: alcohol dehydrogenase, aldehyde dehydrogenase, flavin monooxygenase,
monoamine oxidase, xanthine oxidase, esterase
38.
Urine – physiological and pathological parts
Physiological - amonia, sulphate, phosphate, chloride, magnesium, calcium, potassium, sodium, cretinine, uric acid,
urea, water (95%)
Pathological - large amounts of kations and anions, amino acids, blood, glucose, ketones, bilirubin (conjugated),
leukocytes,
39.
Factors affecting reliability of biochemical results and their interpretation
40.
Clinical biochemistry (importance, biological material and its processing)
III. The oral biochemistry
1.
Digestion in mouth
Saliva is a watery substance secreted by salivary glands. Contains alfa-amylase that beginning the process of
digestion of dietary starches and fats; also play role in breaking down food particles entrapped within dental
crevices, protecting teeth from bacterial decay. The digestive funcions of saliva include moistening food.
Salivary glands also secrete salivary lipase to begin fat digestion.
2.
Biochemistry of connective tissue, the types and cells of connective tissue
3.
Synthesis and degradation of collagen, collagen abnormalities
Synthetized - by fibroblasts, procollagen is cleaved by peptidases. Posttranslational modification - hydroxylation of
proline and lysine (prolyl and lysyl hydroxylase), reductin agent - ascorbic acid. Hydroxylated polypeptides are next
glycosylated by glucose and galactose by glucosyl or galactosyl transferase. Glycosylation occurs only on the
hydroxy lysine residues.
After hydroxylation and glycosylation is formed procollagen that is realased extracellulary. Outside the cell
procollagen is cleaved by peptidases (C/N terminus) - tropocollagen molecules change into collagen with cross
links.
Degradation - by collagenases during bone and cartlige resorption, osteoporosis, tumors…
Disorders - osteogenesis imperfecta, EDS, epidermis bullosa, alport syndrome
4.
Elastin, structure and function
Structure - glycine proline alanine valine, HyPro smal amount. Function - helps skin to return to its original
position. ELN is a gene that encode gylcine and proline (hydrophobic) which form hydrophobic regions bounded
by crosslinks between lysine residues.
5. Interfiber of connective tissue, glycosaminoglycan’s
+
6. Metabolism of proteoglycans
Proteoglycans and glycoaminoglycans have common structure - linear polysacharide chains with hexosamine
alternating with another sugar. (polysacharide covalently linked to protein; may contain sulfate resulting in a strong
negative charge.
Function - support matrix of CT in the skin
Biosynthesis - formation of the protein core with sequential addition of sugars and sulfate to nonreducing ends of
growing chains. Formation takes place in Golgi apparatus.
Degradation - endoglycosidases (cleaving inside of the chain), exoglycosidases (peptide or carbohyl end of the
chain) and proteases which work in concert to degrade.
7.
Basal membranes, laminins
8.
Role of fluorides in the metabolism tooth
Prevention of dental caries. Carious enamel may take up 10 times more fluoride than healthy enamel to inhibit
expansion of carious lesion. Dentin contains more fluoride, because its more similar than bone; highest
concentration found adjacent to pulp (close to blood supply). Low and moderate intake results to - skeletal
fluorosis, mottled enamel, osteosclerosis, bony projections, calcification of ligaments.
Remineralizaion - greater concentration of fluoride released from the dissolved enamel or already present on the
plaque, the more will remineralization be favored and carious process be slowed.
Antibacterial effects - inhibition of enzymes essential to cell metabolism and growth; can strip off bacteria from
hydroxyapetite; fluoride can bind more effectively to positively charged areas on the apatite crystal than can the
bacteria. Inhibits dental plaque formation.
9.
Composition and metabolism of mineral part of teeth and bones
Inorganic components - hydroxyapatites Ca5(PO4)3(OH), calcium phosphate, calcium carbonate, calcium fluoride,
calcium hydroxide, citrate, calcium crystal salts
Calcium - absorbed in duodeum against concentration gradient with energy, vit D increase absorbtion - induces
synthesis of calbindin (calcium carrier protein); PTH increase calcium transport; acidity favors calcium absorption, lys and
arg also increase. Phosphate decrease absorption by precipitation, oxalates also decreases calcium level. Activation
enzymes pyruvate dehdrogenase, kinase, carobxylase, glycogen synthase, adenyl cyclase.
Teeth - soluble and insoluble protiens, collagen, lipid, citrate, gag, gp, peptides, serum proteins
Bone - hydroxyapatite (10:6), organic phase (collagen, noncollagenous proteins, lipids), water, proteoglycans,
glycoproteins, fluoride, potassium
Contains bone marrow - erythopoetin stimulates synthesis of heme; parathormone realases phosphorus form bones;
calcitonin- reabsorption of bone and osteoclasts.
Phosphorus - formation of bone and teeth
Mineralization homogenous [ca, p] ions incr by enzymes, building stones. hetero. seeding subst(colagen, phospho
prot, chndroitin sulfate, lipid) mould where are crystals. matrix agregate: vesicle containing apatite crystals near the
cartlige agregate and form mineralized matrix, vesicle: I sub from cart cels, break down of proteoglycans+gag, II
detached pieces of cart cels bound by trilamelar mem
10.
Composition and metabolism of organic part of teeth and bones
Bone org cels(osteocytes, blsts, clast) osteoid(proteoglycans, glycoprot); RANK mem prot on osteoclasts, acitivation
upon ligand binding; RANKL primary mediator of osteoclasts diferentiation; OPG block rank and bind to its receptor,
osteoclasts cannot form. Osteoblasts produce organic part of bone matrix - osteoid (proteoglycans, glycoproteins).
Collagen type I (triple helix inits, alpfa 1 and alpha2) - postranslational hydroxylation on lysines and prolines (prolyl and
lysyl hydroxylase by glycosyl or galctosyl transferase) - procollagen unit. Osteocalcin - protein carboxylated on
glutamate residues with help of vit K.
11.
Formation and importance of vitamin D, the role of hydroxylation enzymes in the process of
vitamin D formation
D2 and D3 inactive form, activation in the kidney
and liver.
Vit D is responsible for calcium level.
Importance: bone formation, anticancer
properties, reducing risk of stroke and
cardiovascular diseases, during pregency women
often obtain proper immune effects.
12.
Defects of vitamin D synthesis. Diagnostic importance of vitamin D
Diagnostic importance: cardiovascular diseases, autoimmune diseases, infections, DNA repair, osteoporosis.
Defects: hypocalcemia, hypercalcemia.
13.
Metabolism of calcium, factors influencing absorption of calcium
1. Vit D - induces the synthesis of calbindin (carrier protein for
Ca) increasing Ca absorption.
2. Parathyroid hormone - increases Ca transport.
3 Acidity - absorbed in acidic medium.
4. Lactose - form acid, increases absorption
5. Need for calcium - efficiency of calcium
6. Amino acids - Lysine and Arginine increases Ca absorption.
Kidney - It processes vitamin D3 into calcitriol, the active form
that is most effective in promoting the intestinal absorption of
calcium. This conversion of vitamin D3 into calcitriol, is also
promoted by high plasma parathyroid hormone levels.
14.
Defects of calcium metabolism
Hypocalcemia parathyroid related or vit D related. Vitamin D related hypocalcemia may be associated with a lack of
vitamin D in the diet, a lack of sufficient UV exposure, or disturbances in renal function. Low vitamin D in the
body can lead to a lack of calcium absorption and secondary hyperparathyroidism (hypocalcemia and raised
parathyroid hormone). Symptoms of hypocalcemia include numbness in fingers and toes, muscle cramps,
irritability, impaired mental capacity and muscle twitching.
Hypercalcemia occurs most commonly in breast cancer, lymphoma, prostate cancer, thyroid cancer, lung cancer,
myeloma, and colon cancer. It may be caused by secretion of parathyroid hormone-related peptide by the tumor
(which has the same action as parathyroid hormone), or may be a result of direct invasion of the bone, causing
calcium release. Symptoms of hypercalcemia include anorexia, nausea, vomiting, constipation, abdominal pain,
lethargy, depression, confusion, polyuria, polydipsia and generalized aches and pains.
15.
Calcium in blood, factors regulating blood calcium level, the role of PTH, vitamin D
and calcitonin
Ca2+ control - vit d, calcitrol, acidity, parathormone forms: diffusible: ionized 50%, complex 10%(citrate, phosphate);
nondiffusible: prot bound ca 40%(bound to negat. charged albumin). PTH in conjugation with calcitriol increasing calcium
level (releasing Ca from bone), calcitonin stimulate absorption Ca into the bone.
Level : 2.2-2.6 mmol/l
16.
Metabolism of phosphorus
Phosphorus - bones, teeth; 3.4-4.5; PTH relase it from the bone into urine
Determination with amonium molybdate, spectrophotometric method in which vanadate and ammonium molybdate
react with in acidic medium with phosphoric acids forming yellow complex of molybdate-vanadate phosphoric acid.
Content of inorganic phosphorus determined after depolarization, lipoid phosphorus by precipitation after mineralization
of blood serum.
Concentration
Inorganic phosphorus result of balance between phosphorus intake in food and mobility of stores in body tissues
(hydroxyapetite) and urine excretion. Depends on proportion of anabolic and catabolic processes in tissues.
Phosphate concentration in blood serum depends on functional state of parathyroid gland and excreation ability of
kidneys (globular filtration and resorption in tubules).
Loss phosphorus by urine increasing by strenuous exercise or severe diseases.
17.
Mineralisation and demineralisation of bones
inorg bone - hydroxyapetite, calcium carbonate
mineralization homo [ca, p] ions incr by enzymes, form stones. hetero
seeding subst(colagen, phospho prot, chndroitin sulfate, lipid) mould where are crystals.
bone demineralisation leads to osteoporosis, Osteoporosis is a disease in which bones are losing the mineral content
and the weight, becoming fragile and prone to fracture.
18.
Formation and properties of enamel
Amelogenesis - ameloblasts formation. Amelogenesis is formation of enamel that begins when crown is forming during
bell stage of tooth development after dentinogenesis (dentin formation). Dentin must be present for enamel to be formed.
Message is sent from odontoblasts to the inner enamel epithelium causing epi cells to differentiate into secretory
ameloblasts. Stages - inductive, secretory and maturation. Inductive = ameloblasts differentiate from inner enamel
epithelium; Secretory = proteins and org matrix form mineralized enamel; Maturation = completed enamel mineralization.
19.
Formation and composition of dental plaque
PLAQUE dry weight 50%bactr prot, 25%carbs, 10% inorg ions calcium and phosphates. formation mineralized
bacterialdeposit, formation of pelicle, bacteria coloning then microcolonies and maturation
20.
Dental caries formation
CARIES miller’s- decalcification of dentine and enamel
factors carbohydrates, acids (disoluton of minerals), microorg.(prod acids that cause proteolysis)
carbohydr increse caries incidence, bound to salivary prot and it’s not avaible for microbal degr
acids prod by enzymatic breakdown and lactic acid
Proteolysis-chelation - caries ocurs as a result of degradation of org sub and dissolution of minerals by chelation
(complexing metal ions through coordinate covalent bound resulting in highly stable ionized compound)
-PLAQUE dry weight 50%bactr prot, 25%carbs, 10% inorg ions calcium and phosphates
formation mineralized bacterial deposit, formation of pelicle, bacteria coloning then microcolonies and maturation
-SALIVA lubrication(mastication, deglutition, speaking), digestion(amelase digest starch), prevention of
caries(supersaturated with ca2+, prevent precipitation, inhi microorg and enolase), antiinfection (imunoglobulins,
lactoferin, lysozyme), taste
21.
Prevention of dental caries
22.
Healthy diet, tooth paste, fluorization, diet with small amount of sugars, brushing after each meal, avoid acidic
juices…
Requirements of healthy diet, basal metabolism
23.
1/7 fat; 1/7 protein; 5/7 carbonhydrate. Balanced diet: carbonhydrates, proteins, fats, water, vitamins, minerals.
Carbonhydrates - broken down by the digestive system into energy in form of glucose; too much energy lead to
accumulation of fat (energy storing). E is for: transport, synthesis of macromolecules, cell division, muscle
contraction. Fructose is healthier than glucose.
Proteins - building blocks essential for growth and repair of body tissues. Are broken down into amino acids which
are absorbed into the blood. A balanced diet includes all of the essential amino acids.
Fats - broken down into fa and glycerol - cell membranes and steroid hormones. Saturated fats and cholesterol are
less healthy than unsaturated fats (soya); omega 6 and omega 3 fatty acids are healthy for diet.
Minerals - macro and micro minerals; essential for bone and teeth formation (calcium); Ca-dairy foods, Fe-meats.
The role of diet in the process dental caries formation and in prevention of formation of caries
Frequent consumption of fermentable carbohydrates that have low oral clearance rates increases the risk for enamel
caries and perhaps is even more dangerous for root surfaces. Highly acidogenic snack foods should be
consumed at mealtimes to reduce the risk, and between-meal snacks should be either nonacidogenic (such as
xylitol products) or hypoacidogenic (such as sorbitol and HSH products).
24.
Formation and importance of saliva
Saliva is a watery substance located in the mouths of animals, secreted by the salivary glands. Human saliva is 99.5%
water, while the other 0.5% consists of electrolytes, mucus, glycoproteins, enzymes, antibacterial, and bacteria
compounds such as secretory IgA and lysozyme.
SALIVA prevent caries (sat with ca2+, prevent precipitation, inhi microorg and enolase), antinfection
(imunoglobulins, lactoferin, lysozyme) composition na k ca mg, alfa amylase, urea hormones, neutral lipids
glycolipids p-lipid, nonimunoglob prot (lactoferin lysozyme peroxidase statherin)
cystatnins antiviral, antibac, mineral, coating; mucins antiviral, antibac, dig, librication, coating; amylases antibac, dig,
coating; histatins antibac, bufer, mineral, antifungal; peroxidases antibac; carbonic anhydrase bufer; lipase dig;
staterins mineral, lubrication, coating; pro mineral, coating
25.
Composition of saliva, antiviral and antibacterial role of saliva
Composition - 99% water, 0,5% electrolytes, mucus, gp, enzymes, antibacterial and bacteria compounds
(antibobies and lysozyme). Antiviral - cystatnis, mucins; Antibacterial - cystatins, mucins, amylases, histatins
26.
The function of saliva proteins, statherin, mucins, proline rich proteins, lactoferrin
Proline-rich proteins function in enamel formation, Ca2+-binding, microbe killing and lubrication, cystatnins
antiviral, antibac, mineral, coating; mucins antiviral, antibac, dig, librication, coating; amylases antibac, dig,
coating; histatins antibac, bufer, mineral, antifungal; peroxidases antibac; carbonic anhydrase bufer; lipase
dig; staterins mineral, lubrication, coating; pro mineral, coating, lactoferrin has antibacterial, antiviral,
antiparasitic, catalytic, anti-cancer, anti-allergic and radioprotecting functions and properties.
27.
Salivaryperoxidase system
Source of the hydrogen peroxide (H2O2) usually is the reaction of glucose with oxygen in the presence of the
enzyme glucose oxidase that also takes place in saliva. Glucose, in turn, can be formed from starch in the
presence of the saliva enzyme amyloglucosidase.
28.
Sialolithiasis–salivary stone
Sialolithiasis is a condition where a calcified mass or sialolith forms within a salivary gland, usually in the duct of the
submandibular gland (also termed "Wharton's duct"). Less commonly the parotid gland or rarely the sublingual
gland or a minor salivary gland may develop salivary stones. Certain substances in your saliva, such as calcium
phosphate and calcium carbonate, can crystalize and form stones that range in size from a few millimeters to
more than two centimeters. When these stones block your salivary ducts, saliva builds up in your salivary
glands, which makes them swell. Cause isn’t known.
29.
The tongue and receptors of the taste
30.
Dental hygiene, active ingredients in toothpastes and mouthwashes
Tooth paste - abrasives (removing plaque, contains aluminum hydroxide, calcium carbonate, calcium hydrogen
phosphates, hydroxyapetite), fluorides (sodium fluoride, prevent caries), surfactants (SLS), antibacterial agents
(zinc chloride), flavorants (peppermint), remineralizers (hydroxyapetite nanocrystals, calcium phosphates). In
addition to 20–42% water, toothpastes are derived from a variety of components, the three main ones being
abrasives, fluoride, and detergents.