Download Recitation 3 - Department of Chemistry ::: CALTECH

Intermediary Metabolism
and Enzymes
Metabolism: comprises the entire set of chemical reactions that occur in a living organism that allow it to
reproduce, develop, maintain its structure and respond to the environment.
These chemical reactions form an intricate network of pathways and cycles in which the flow of reaction
products (metabolites) is determined by many regulatory mechanisms.
Catabolism, the breaking down of
complex molecules and degredation
Metabolism
Anabolism, processes related to the synthesis of
complex organic substances like protein synthesis, DNA
synthesis
Energy and Energy Conversion
Two laws of thermodynamics:
• energy is neither created or destroyed, when energy is converted form one form
to another form the total energy before and after the conversion is the same.
• When energy is transformed, some forms are unavailable to work with, lost as
heat
We eat carbohydrates:
In glycolysis, a series of enzymatic reactions will convert sugars
(typically glucose)
pyruvate.
During this process, small amounts of ATP are generated and
electron carriers are loaded with electrons (NAD+ is reduced to
NADH + H+)
Consequently, pyruvate is translocated to the mitochondria,
decarboxylated and converted into acetyl-CoA
Acetyl-CoA then enters the tricarboxylic acid (TCA) cycle,
also called Krebs cycle, by condensing with oxaloacetate to
form citrate. As the acetyl-CoA goes through this cycle, things
are bounced off and things that are bounced off are these high
energy carriers. High energy carriers bounce down a staircase
A series of oxidation reactions then ensue with the result that
two carbons are expelled as CO2, (G/A)TP is produced and the
electron carriers (NAD+ and FAD+) are reduced.
ATP
ATP hydrolysis and result in ADP!
Enzymes:
• Enzymes speed up reactions without being
changed themselves. Most of the enzymes are proteins
Activating Energy
• Enzymes work with lowering the activation energy.
Regulation of enzymes:
• Irreversible inhibition:
Diisopropyl
fluorophosphate
• Reversible inhibition:
(C ) Allosteric inhibition