Work Sheet 20
Introduction
to Metabolism
1. Define anabolism, catabolism, committed
step, rate-limiting step and steady- state.
Anabolism: synthetic
process.
Catabolism: degradative
process.
Committed Step: the
first reaction unique to a pathway.
Rate-Limiting Step: slowest
reaction of the pathway, determines the rate of the pathway.
Steady-State: unidirectional
flow of metabolites ---> concentration of metabolites that remains
relatively constant until the system is perturbed.
2. Explain the
general types of metabolic regulation.
Enzyme Kinetics
Allosterism
Feedback Inhibition
Covalent Modification
Polymerization
Regulatory Proteins
Proteolytic Activation
Induction
3. List the three energy storage forms and the five primary circulating fuels.
Three Energy Storage Forms:
glycogen (carbohydrates)
protein (amino acids)
triglycerides (fatty acids)
Five Circulating Fuels:
glucose
lactate
amino acids
free fatty acids
ketone bodies
Key Metabolic Intermediates ("crossroads" in metabolism):
glucose-6-phosphate
pyruvate
acetyl CoA
4. Identify where
specific biochemical processes occur
in the cell.
The Nucleus: Control center of the cell, containing 95% of its DNA.
DNA replication and transcription of DNA into RNA.
Endoplasmic Reticulum (ER):
Aqueous region enclosed w/in the ER is the lumen.
Protein synthesis/export.
Many enzyme systems involved in the metabolism of lipids.
Golgi Apparatus: Protein modification/sorting/packaging/transport.
Mitochondria: Central role in energy transduction.
Oxidative energy metabolism.
Mitochondrial Matrix: The inner
mitochondrial membrane and the matrix contain many of the enzymes involved
in aerobic energy metabolism.
Thermodynamics
in Metabolism
1. List the
general features and functions of ATP.
The energy of ATP is stored in two phosphoanhydride bonds-
between the g and b phosphates, -7.3 kcal/mol
between the b and a phosphates, -6.6 kcal/mol
removal of the a phosphate does not release energy
2. Define high energy phosphate transfer potential
and identify ATP, phosphocreatine , 1,3- bisphosphoglycerate
and phosphoenolpyruvate as high energy phosphorylated compounds.
The energy of ATP is stored in two phosphoanhydride bonds-
between the g and b phosphates, -7.3 kcal/mol
between the b and a phosphates, -6.6 kcal/mol
removal
of the a phosphate does not release energy
phosphocreatine, -10.3 kcal/mol
1,3-bisphosphoglycerate, -11.8 kcal/mol (glycolysis)
phosphoenolpyruvate, -14.8 kcal/mol (glycolysis)
3. Identify the
various electron carriers.
Reductants (donate electrons): NADH, NADPH, FADH2
Oxidants (accept electrons): NAD+, NADP+, FAD
4. Describe the significance of the adenylate kinase reaction in metabolic regulation.
The increase in AMP is what's important here......
Because AMP is an allosteric regulator that signals a low energy state in cells --------->
rise in AMP increases metabolism through pathways to restore energy (i.e. glycolysis).