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Dr Lihong（立红） Xu(徐）
Prof of Biochemistry and
Molecular Biology
生物 化学与分子 生物学 教授
xulihong@zju.edu.cn
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I. Biomolecules
II. Enzymes
√
√
III. Metabolic pathways, their regulation
and metabolic interrelationships
IV. Hormones
V. Fat soluble and water soluble vitamins
VI. Hematic Biochemistry
VII. Molecular Biology
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长城
西湖
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We are the most important organism
in the earth.
T or F ?
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N2
nitrogen-fixing bacteria
NH3
Urea
mammals
denitrifying bacteria
nitrifying bacteria
animals
plants
Amino
acids
plants
NO3-
NO2Cycling of nitrogen
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in the biosphere
photosynthetic
(autotrophic)
heterotrophic
Cycling of carbon dioxide and oxygen between the
autotrophic (photosynthetic) and heterotrophic
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domain in the biosphere.
Phototrophs, an organism that can use the
energy of light to synthesize its own fuels from
simple molecules such as CO2, O2, and H2O, as
distinct from a chemotroph.
photosynthesis
Autotrophs, an organism that can synthesize its
own complex molecules from very simple carbon
and nitrogen sources, such as CO2 and NH3.
Can we do these?
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We can eat. We must eat.
Chemotroph, an organism that obtains
energy by metabolizing organic compounds
derived from other organisms.
We, animal, live on Phototrophs and
Autotrophs.
HOW do we get the energy and the
building blocks of macromolecules?
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III. Metabolic pathways, their regulation
and metabolic interrelationships
III-I
Metabolism
III-II
Carbohydrate metabolism
III-III
Lipid metabolism
III-IV
TCA cycle and biological oxidation
III-V
Protein turnover and amino acid metabolism ;
Nucleotide metabolism
III-VI
Regulation of the metabolic pathways
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general concepts and
characteristics of metabolic
pathways.
III-I
Metabolism
III-II
Carbohydrate metabolism
III-III
III-IV
III-V
III-VI
Digestion and absorption of dietary carbohydrates
Pathways of glucose metabolism: glycolysis
Pentose phosphate shunt
Gluconeogenesis
Glycogenolysis, glycogenesis
Galactose and fructose metabolism
Glycogen storage disease
Inborn errors of glucose metabolism
Regulation of glucose metabolism.
Digestion and absorption of dietary fats.
Biosynthesis and degradation of fatty acids,
Lipid metabolism
phospolipids and triacylglycerols
TCA cycle and biological oxidation
Biosynthesis of cholesterol, chemistry and
metabolism of lipoproteins.
Protein turnover and amino acid
Hyperlipoproteinemias
metabolism ;Nucleotide Metabolism Lipid storage disease.
Ketone bodies: their synthesis, utilization
Regulation of the metabolic pathways
and conditions leading to ketoacidosis,
prostaglandin.
Carbohydrate, lipid and amino acid metabolism
Interlinks between these pathways.
Organ interrelationships in metabolism,
Blood glucose regulation, and its impairment in
diabetes mellitus.
Metabolic adaptation in the fed state, fasting
and prolonged starvation.
Metabolic derangements and adaptations in
diabetes mellitus.
Digestion and absorption of dietary protein
General reactions, transamination, its metabolic
and diagnostic significance
Disposal of amino acid nitrogen and detoxication
of urea
Metabolic fate of amino acid carbon skeleton
Sulphur containing amino acids
In born errors of branched chain and aromatic
amino acids
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Important amino acid derivatives.
Nucleotide metabolism
III-I Metabolism
III-II Carbohydrate metabolism
III-III Lipid metabolism
III-IV TCA cycle and biological oxidation
III-V
Protein turnover and amino acid
metabolism
III-VI Regulation of the metabolic pathways
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III-I Metabolism
general concepts and
characteristics of metabolic
pathways
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what
Q
why
A
how
Be sure to
REMEMBER
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Q
Where do we get energy ?
Where do we get building blocks of macromolecules
to build ourself?
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beings and animals ,obtain energy and building
A We,human
blocks of macromolecules from ENERGY –RICH
MOLECULES, produced by autotrophs and phototrophs,
as well as other chemotrophs
nutrients
protiens
amino acids
polysaccharides
monosaccharides
lipids
glycerol
fatty acids
vitamins
minerals
Thousands of complex reactions
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Chemical
reactions
Catalyzed by
enzymes
Certain
compartment
in the CELL
Thousands of complex reactions
Energy
Other molecules
Building blocks
needed in the body
To be alive
How can the reactions happen?
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In a reversible reaction,
what will decide the direction of the
reaction ?
A
+ B
C
Cell, isothermal
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Basic concepts
Free energy (G)
A thermodynamic quantity, whose change at
constant pressure is indicative of the spontaneity
of a process.
Free-energy change (ΔG)
The amount of free energy released (negative ΔG)
or absorbed (positive ΔG) in a reaction at constant
temperature and pressure.
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The energy that cells can and must use is
FREE ENERGY,
Living organisms require
a continual input of FREE ENERGY
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Q What does △G mean?
A
△G will determine
whether the reaction will be spontaneous
at constant temperature and pressure.
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Units of energy (will be used in description of free energy)
A calorie (cal) is equivalent to the amount of heat required to
raise the temperature of 1 gram of water from 14.5°C to
15.5°C.
A kilocalorie (kcal) is equal to 1000 cal.
A joule (J) is the amount of energy needed to apply a 1-newton
force over a distance of 1 meter.
A kilojoule (kJ) is equal to 1000 J.
1 kcal = 4.184 kJ
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Change in free energy (△G) during a reaction.
favorable process
A can be spontaneously
converted into B
unfavorable process
B cannot be spontaneously
converted into A 23
1. A reaction can occur spontaneously only if
△ G is negative. Such reactions are said
to be exergonic.
2. A system is at equilibrium and no net
change can take place if △ G is zero.
3. A reaction cannot occur spontaneously if
△ G is positive. An input of free energy
is required to drive such a reaction.
These reactions are termed endergonic.
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Q
How is the free energy inputted to drive
a reaction with positive △ G?
A
A thermodynamically unfavorable reaction
can be COUPLED by a thermodynamically
favorable reaction.
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Favorable and unfavorable processes could be coupled
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Energy coupling
in mechanical and
chemical processes
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the chemical intermediate B, common to both
reactions, couples the reactions.
The overall free-energy change for a chemically coupled
series of reactions is equal to the sum of the free-energy
changes of the individual steps.
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A thermodynamically unfavorable reaction
can be DRIVEN by a thermodynamically
favorable reaction to which it is coupled.
as long as overall △G is negative.
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Q
HOW does the cell use
FREE ENERGY?
A
The cell uses ATP and other energy-carrier
compounds , transformed from FREE
ENERGY.
Both chemotrophy and phototrophy (as well as
autotrophy) transform the free energy into ATP
and other energy-carrier compounds.
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The First Law of Thermodynamics
The energy can be
neither created nor destroyed.
The amount of energy in the universe is
constant.
The energy can be converted from one
form into another.
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ATP
Basic concepts
Adenosine triphosphate, ATP
Adenosine diphosphate, ADP
Adenosine monophosphate, AMP
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ATP is an energy-rich molecule because its triphosphate
unit contains two phosphoanhydride bonds.
phosphate group transfer potential
phosphoanhydride bonds,
high-energy phosphate bonds
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A large amount of free energy is liberated when ATP is
hydrolyzed to
ADP + Pi
or
AMP + PPi
exergonic
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ATP－ADP cycle
a fundamental model
of energy exchange in
biological system
Motion, active transport, signal amplification, and
biosynthesis can occur only if ATP is continually
regenerated from ADP.
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Q
There are two ways to form ATP.
A
•Substrate Level Phosphorylation
•Oxidative Phoshorylation
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Q
Is ATP the only energy-carrier compound ?
A
There are some phosphorylated compounds
ranking to energy-carrier compounds,
like……. (filled it by youself)
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Basic concepts
Phosphate group transfer potential
The tendency of a phosphorylated molecule
to undergo hydrolysis
During its hydrolysis, energy is released.
The phosphoryl transfer potential is an important
form of cellular energy transformation.
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ATP is not the only compound with a higy phosphoryl transfer potential.
other energy-carrier compounds
Glycolysis
intermediate
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Q
Why is ATP the most important energycarrier compound ?
A
ATP is highly accessible for energyrequiring processes, called energy
currency.
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Some compounds have a higher phosphoryl
transfer potential than that of ATP and can be
used to phosphorylate ADP to form ATP.
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It is significant that ATP has a phosphate group
transfer potential that is intermediate among
the biologically important phosphorylated
molecules.
This intermediate position enables ATP to
function efficiently as a carrier of phosphoryl
groups.
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The amount of ATP in muscle
suffices to sustain contractile
activity for less than a second.
Creatine phosphate is the major source of
phosphoryl groups for ATP regeneration
for a runner during the first 4 seconds of a
100-meter sprint
more
efficiently
,
Importance of ATP
during exercise
more
rapidly
The ATP must be regenerated by
metabolic pathways.
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Q
HOW is the free energy transformed into
ATP and other energy-carrier compounds
A
The free energy is transformed into ATP and
energy-carrier compounds through
metabolism of nutrient molecules.
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Q
HOW do we get building blocks
of macromolecules for our body?
A
The build blocks is derived from
metabolism of nutrient molecules.
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pathway
Basic concepts
is formed by the coupling of enzyme-catalyzed
reactions such that the overall free energy of the
pathway is negative.
The product of one reaction is
the substrate of subsequent reaction.
Specific pathways constructed from individual
reactions must satisfy minimally two criteria:
•
•
enzyme
the individual reactions must be specific.
the entire set of reactions that constitute the pathway
must be thermodynamically favored.
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overall △G is negative
Basic concepts
catabolic pathways
serve to capture chemical energy in the form
of ATP from the degradation of energy-rich
fuel molecules, as well as extract reducing
power from the diet, convert molecules in the
diet into building blocks needed for the
synthesis of complex molecules.
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Basic concepts
anabolic pathways
combine small molecules to form complex
molecules, in which the energy and reducing
power are needed, supplied in the form of
ATP and NADPH respectively.
Anabolic reactions often
involve chemical reduction.
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Most catabolic pathways involve
the oxidation of organic molecules coupled to
the generation of both energy (ATP) and reducing
power (NADH).
In contrast, anabolic pathways generally involve
the use of both ATP and reducing power
(usually in the form of NADPH) for the
production of new organic compounds.
NADH
NADPH
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NADP and NAD
coenzyme
NAD, without -PO4251
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Energy relationships
between catabolic and
anabolic pathways
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Basic concepts
Metabolism
different pathways intersect, forming an
integrated and purposeful network of
chemical reactions
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Thousands of metabolic reactions can be
subdivided into just six types.
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Q
Where do we get nutrients?
A
We obtain carbohydrates, lipids , proteins,
main energy-providing compounds, and
other nutrients from foodstuff.
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Carbohydrates
lipids
proteins
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Q
What is the general process to
extract energy from foodstuffs?
A
There are three stages in catabolism.
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Large molecules in food are broken
down into smaller units. No useful
energy is captured in this phase.
These numerous small molecules are
degraded to a few simple units that
play a central role in metabolism.
Some ATP is generated in this stage.
Cell
ATP is produced from the complete
oxidation of the acetyl unit of acetyl
CoA, the final common pathways in
the oxidation of fuel molecules.
Three stages in the generation of energy from the oxidation of foodstuffs
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Main topics in
the Part III
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Summary for the chapter
 The energy that cells can and must use is free energy.
 △G will determine whether the reaction will be
spontaneous at constant temperature and pressure.
 A thermodynamically unfavorable reaction can be
coupled by a thermodynamically favorable reaction.
 There are some phosphorylated compounds
ranking to energy-carrier compounds
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 ATP is highly accessible for energy-requiring
processes, called energy currency.
 The free energy is transformed into ATP and energycarrier compounds through metabolism of nutrient
molecules.
 The build blocks of macromolecules are derived
from metabolism of nutrient molecules.
 We obtain carbohydrates, lipids , proteins, main
energy-providing compounds, and other nutrients
from foodstuff.
 There are three stages in catabolism.
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Summarize
Q
&
A
by yourself
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