Organic Chemistry
Biological Molecules
Classes of Biological Molecules
1.
2.
3.
4.
carbohydrates
lipids
proteins
nucleic acids
Biological Molecules
These macromolecules are polymers made
up of smaller parts called monomers.
Ex- DNA made of nucleotides
Proteins made of amino acids
Condensation
Condensation reactions link monomers
together to form polymers and water.
Hydrolysis
Hydrolysis breaks a polymer chain between
monomers and adds water. A hydroxyl joins
one monomer and a hydrogen joins the
other.
Hydrolysis
Example of Hydrolysis
Breakdown of milk sugar lactose by lactase.
Lactose intolerant individuals lack the
lactase enzyme.
CARBOHYDRATES
CARBOHYDRATES
Sugars and Starches.
General formula Cn(H2O)n
End in -ose
Carbohydrate Functions
1.
2.
3.
4.
Primary source of energy
Transport and storage of energy
Structural molecules
Recognition molecules
TYPES OF CARBOHYDRATES
1. Monosaccharides
2. Disaccharides
3. Polysaccharides
MONOSACCHARIDES
Simple sugars
Pentoses and hexoses
Polar and water soluble
High melting points
Main fuel molecule for cellular work
In aqueous solutions exist as cyclic and
open chain structures
GLUCOSE- an aldose
Fructose- a ketose
Galactose-an aldose
Structural Isomers
Stereoisomers
Glucose
Blood sugar
Regulated by the hormone, insulin.
Insulin
Helps control blood glucose levels by
signaling the liver and muscle and fat cells
to take in glucose from blood.
When body has sufficient energy, insulin
signals liver to take up glucose and store its
as the polymer glycogen.
Insulin
Made by pancreas in cells called Islets of
Langerhans.
Not enough insulin can result in diabetes.
Too much insulin can result in
hypoglycemia.
DISACCHARIDES
Double sugars
Formed by condensation reactions.
C12H22O11
Sucrose is extracted from sugar beets and
sugar cane.
Maltose
2 glucose units
A product of starch digestion
Found in germinating seeds
Used in making beer
Lactose
Formed from glucose and galactose
Oligosaccharides
Several monosaccharides linked together
via condensation rxns.
Often bonded to lipids and proteins on cell
membrane surfaces. Serve as receptors for
recognition signals. ABO blood groups get
specificity from oligosaccharides.
POLYSACCHARIDES
Contain 12 or more monomers
May be linear or branched
Are storage and structural molecules
TYPES OF POLYSACCHARIDES
1. Glycogen-carbohydrate storage molecule
of animals. Stored in liver and muscle
cells.
2. Starch-carbohydrate energy storage
molecule of plants. (potatoes and grains)
3. Cellulose-plant structural compound.
Most abundant organic compound
Most animals lack enzymes to
digest
4. Chitin-structural carbohydrate found in
exoskeleton of insects and crustaceans.
Found in cell wall of fungi
Made of glucosamine
Used to make surgical thread.
LIPIDS
Fats and Oils, Waxes, and Steroids
Not made of polymers--large nonpolar
biological molecules.
Hydrophobic
Functions of Lipids
1. Component of cell membranes
2. Store energy-main function
3. Regulate cellular processes
4. Control water loss
5. Insulation
6. Cushion vital organs
Soaps are sodium salts of fatty acids
Soap cleans because the nonpolar end of
the molecule bonds to nonpolar dirt and
grease, while the polar end dissolves in
water and rinses away the dirt.
Fatty Acids
Building block of lipids
Usually have an even # of Carbons (12-14)
General formula
CH3(CH2)nCOOH
Fatty Acids
Fatty Acids are long chain carboxlic acids
and are either:
1. Saturated (animal fat)
2. Unsaturated (corn oil, olive oil, vegetable
oil)
Hydrogenation saturated unsaturated
compounds.
Fatty acids
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Hydrogenation of Oleic Acid
Oleic Acid + H2 → stearic acid
Unsaturated Fatty Acids
Double bond are usually cis geometry- this
causes a kink or bend in structure that
prevents the fatty acids from packing
together, thus have a lower MP than
saturated fatty acids.
Types of Lipids
1. Fats and Oils
2. Phospholipids
3. Waxes
4. Steroids
FATS AND OILS
Also called triglycerides. Consist of 3 fatty
acids bonded to glycerol via ester bonds.
Liquids are called oils and solids are called
fats.
Stored as fatty acids in fat cells. Fat in cells
can be broken down by enzymes when
energy is scarce.
Adipose Tissue
Saponification
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PHOSPHOLIPIDS
Type of triglyceride in which one of the fatty
acids is replaced by a polar phosphate
group (PO4-3)
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Phospholipids make up cell membrane
along with proteins (Fluid Mosaic
Model)
Lipid bilayer with phospholipids
arranged tail to tail.
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Phospholipases are enzymes in snake
venom which break down phospholipids in
the cell membranes via hydrolysis reactions.
Rattle snake venom hydrolyzes ester bond
at middle carbon of the phospholipid and
dissolves cell membranes of RBC’s.
Waxes
Lipids formed by combining a fatty acid with
a long chain alcohol.
General formula
CH3(CH2)xCOO(CH2)yCH3
Some plants have a waxy cuticleprevents water loss.
Bees Honeycomb is wax.
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Steroids
Lipids that have multiple cyclic rings all built
from a four ring structure.
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Steroid Hormones
Hormones are chemical messengers that
regulate metabolism.
Steroid hormones include testosterone and
estrogen.
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Cholesterol is another important steroid. It
is an important structural component of cell
membranes. Gives support and fluidity.
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Vitamin D is a steroid used in the formation
of bones.
Proteins
PROTEINS
Come from the Greek word
“proteios”meaning first place
Are organic polymers made of amino acids
linked by peptide bonds.
FUNCTIONS OF PROTEINS
1. Catalysis of chemical rxns (enzymes)
2. Structural support
3. Transport of materials (hemoglobin)
4. Muscle contractions
5. Immune system antibody defense
6. Hormonal and regulatory proteins (insulin)
Amino Acids
Amino acids are the monomer of proteins.
There are only 20 amino acids.
Made up of amino group and a carboxyl
group.
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Examples of amino acids
glycine
phenylalanine
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Amino acids can be hydrophilic or
hydrophobic depending on the R group.
Peptide bond
Bond formed between amino and carboxyl
groups. (Condensation reaction)
New compound is an amide . Two aa’s
make a dipeptide. Most polypeptides are
100 aa’s in length.
Number of possible peptides formed is 20n,
where n is the number of amino acids in the
chain. If there are four amino acids in a
chain, the the possible number of peptides
formed is 204 or 160 000 possible combos.
Peptides are always built by adding aa to
carboxyl end of a growing chain.
Each protein has a unique 3D structure that
corresponds to a particular function.
Denaturation
Process by which polypeptides unravel and
lose their shape, meaning loss of function.
Changing pH, salt concentrations, or adding
heat can denature a protein.
Four Levels of Protein Structure
1. Primary structure-sequence of aa’s
(sickle cell anemia)
2. Secondary structure - parts of polypeptide
coil or fold into local patterns:
a. alpha
helix -coiling
b.pleated sheet- folding
Secondary structure is due to H-bonding
between hydrogens of amino groups and
oxygens of carboxyl groups of neighboring
peptide bonds.
3. Tertiary structure- overall 3D shape of
protein. (interactions among R groups)
a. globular
b. fibrous
4. Quaternary structure-When proteins
consist of 2 or more polypeptide chains.
REMEMBER
FORM FITS FUNCTION!
Alzheimer’s and Parkinson’s involve an
accumulation of misfolded proteins.
Prions are infectious mishapened proteins
causing diseases such as Mad Cow Disease
or Kuru
Enzymes
Biological catalyst.
Lower activation energy of reaction. 5
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Enzyme Catalyzed Reaction
Substrates are reactants. Bond to active
site of enzyme where reaction occurs.
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NUCLEIC ACIDS
Store and transmit genetic information.
DNA
RNA
Monomers are nucleotides.
Parts of a nucleotide
1. Phosphate group PO4-3
2. Nitrogen base
Consist of purines(double nitrogen rings)
& pyrimidines (single nitrogen ring)
a. Adenine-purine
b. Thymine-pyrimidine
c. Guanine-purine
d. Cytosine-purine
e. Uracil -pyrimidine
3. 5-carbon sugar (pentose)
a. ribose
b. deoxyribose
In a nucleotide, the sugar of one nucleotide
is bonded to the phosphate of another
nucleotide to make up the backbone of the
molecule (alternating sugar -phosphate
groups)
Attached to every sugar is a nitrogen base.
DNA
Deoxyribonucleic Acid
Carries genetic info and is expressed by
RNA
Composed of 2 strands
Structure is a double helix and it was
determined by Watson and Crick
Complementary base pairing
DNA REPLICATION
Reproduction of DNA
Protein Synthesis
Transcription-when DNA sequences are
copied by RNA.
Translation is the process by which Amino
acids are sequenced into proteins from
RNA.