CHEM 301 Biochem Final UPDATED
ACTUAL Questions and CORRECT
Answers
For metabolism in multicellular organisms to proceed efficiently, it is important that the final
products be gases, water, or both. Why? - CORRECT ANSWER- ✔✔To maintain
metabolism in a steady state, there must be no possibility of a build-up of final products. The
easiest disposal products are the multicellular organism's universal solvent, gases, or both.
Compare the tendency of NADH to donate electrons and the tendency of oxygen to accept
them. If NADH and oxygen are mixed, will the electrons stay with NADH or go to oxygen? -
CORRECT ANSWER- ✔✔If NADH and oxygen are mixed, electrons will be transferred
from NADH to oxygen with the release of considerable energy:
NADH + ADH + ½ O2 + H+ ↔ NAD+ + H2O εo′ = 1.13 V
What structural feature do the "high‑energy" compounds ATP, FADH2, and NADH share
with acetyl‑CoA? - CORRECT ANSWER- ✔✔The "high‑energy" compounds share an ADP
unit or, in the case of acetyl‑CoA, a closely related derivative.
What is an anabolic process? - CORRECT ANSWER- ✔✔a biochemical reaction that
synthesizes larger molecules from smaller molecules. They are reductive in nature.
What is a catabolic process? - CORRECT ANSWER- ✔✔An oxidative process. A larger
molecule is broken down into smaller ones. They are the primary energy source for
heterotrophic organisms.
Reductive processes require... - CORRECT ANSWER- ✔✔electron sources such as NADPH,
NADH, or FADH2
Oxidative processes require... - CORRECT ANSWER- ✔✔electron carriers such as NAD+,
NADP+, or FAD
Glycolysis is controlled by... - CORRECT ANSWER- ✔✔-how fast glucose flows into the
cell
,-how quickly pyruvate can be used up
-whether any of the ten "products" are diverted to other reactions
-the concentration of catalysts that control the ten reactions
-feedback loops in which products of the ten reactions regulate preceding reactions
3 categories of organic reactions that occur in vivo - CORRECT ANSWER- ✔✔-oxidative
and reductive
-elimination, isomerization, and rearrangement reactions
-group transfer reactions
What makes a high energy compound? - CORRECT ANSWER- ✔✔The magnitude of ΔGo′
of hydrolysis and the redox potential
The more negative ΔGo′... - CORRECT ANSWER- ✔✔The greater the energy release and
therefore the greater energy in the original bond
The energy released comes from 3 sources: - CORRECT ANSWER- ✔✔-resonance: more
structures for products
-electrostatic repulsion: lower in products than reactants
-entropy: greater for products
The greater the gain in resonance stabilization... - CORRECT ANSWER- ✔✔the greater
relief from electrostatic repulsion and the greater gain in entropy produced by a chemical
change, the greater the energy released.
What does εo′ represent? - CORRECT ANSWER- ✔✔The redox potential of compounds in a
standard state.
Glycolysis is inhibited by iodoacetic acid through inactivation of the enzyme
glyceraldehyde‑3‑phosphate dehydrogenase (GAPDH). As a result, there is an accumulation
of fructose‑1,6‑biphosphate. Why is this product more prevalent than
glyceraldehyde‑3‑phosphate and dihydroxyacetone phosphate, the products that form
immediately preceding GAPDH? - CORRECT ANSWER- ✔✔The reaction that converts
fructose 1,6‑bisphosphate to glyceraldehyde‑3‑phosphate and dihydroxyacetone phosphate is
,near equilibrium in vivo (i.e., ΔG near zero), while the preceding reaction producing fructose
1,6‑bisphosphate is not. Therefore it is F1,6BP that will accumulate, not
glyceraldehyde‑3‑phosphate and dihydroxyacetone phosphate.
The "Pasteur effect" is the dramatic decrease in glucose consumption when oxygen is
introduced to an anaerobic fermentation broth. Why do the yeast cells use less glucose after
oxygen is introduced? How much less glucose do they use after oxygen is introduced? -
CORRECT ANSWER- ✔✔The introduction of oxygen allows yeast to convert from
anaerobic to aerobic metabolism. Since aerobic metabolism provides more ATP, the amount
of glucose that must be used to nourish the yeast is much less. Approximately 6% of the
glucose metabolized anaerobically is needed to provide the same amount of energy under
aerobic conditions.
Why do you get hot when you exercise? - CORRECT ANSWER- ✔✔PEP
(phosphoenolpyruvate) is a very high‑energy compound. The reaction that converts PEP to
pyruvate is so highly energetically favourable (very negative ΔG) that there is almost enough
energy in PEP to stimulate production of a second ATP through substrate level
phosphorylation, but it is not used. The excess energy is lost as heat.
What are the three enzymes that are regulated in glycolysis? How does AMP affect
glycolysis? - CORRECT ANSWER- ✔✔The three enzymes that are regulated in glycolysis
are: hexokinase, phosphofructokinase (PFK), and pyruvate kinase. High amounts of AMP
activate PFK and pyruvate kinase, which stimulate glycolysis because ATP is needed.
List the possible uses of pyruvate. - CORRECT ANSWER- ✔✔The possible uses of pyruvate
are:
- ATP production and NAD+ regeneration through TCA cycle and electron transport
- glucose synthesis by gluconeogenesis
- ATP production and NAD+ generation and lactate or ethanol production by fermentation
- alanine synthesis
- oxaloacetate synthesis
What does the liver do with the lactate that is produced during heavy exercise? - CORRECT
ANSWER- ✔✔During heavy exercise, the body needs ATP and generates lactate through
anaerobic respiration faster than the blood can deliver oxygen to continue through aerobic
respiration. Muscle cells cannot use the lactate produced anaerobically during exercise, so the
lactate is dumped into the blood. The liver converts the lactate to pyruvate in the Cori Cycle.
The enzyme lactate dehydrogenase catalyzes this conversion. The pyruvate is then used to
, make glucose by gluconeogenesis in the liver, and can go back into the blood to be taken up
by muscles and used for energy.
What is glycolysis? - CORRECT ANSWER- ✔✔A catabolic process in which glucose is
oxidized and broken down into pyruvate molecules.
The corresponding anabolic pathway by which glucose is synthesized... - CORRECT
ANSWER- ✔✔Gluconeogenesis
The end products of glycolysis are - CORRECT ANSWER- ✔✔2 ATP, 2 NADH, and 2
pyruvate.
Intermediates of glycolysis that are common in other pathways are.. - CORRECT ANSWER-
✔✔Glucose-6-phosphate, Fructose-6-phosphate, Glyceraldehyde-3-phosphate, DHAP, 3-
Phosphoglyceric acid, Phosphoenolpyruvic acid, and Pyruvate
substrate-level phosphorylation - CORRECT ANSWER- ✔✔The synthesis of ATP directly
from a metabolic reaction.
Regulation of Glycolysis - CORRECT ANSWER- ✔✔3 enzymatic points:
- Hexokinase (Glucose <-> G6P)
- Phosphofructokinase (F6P <-> F1,6BP)
- Pyruvate kinase (PEP <-> pyruvate)
Reciprocal regulation - CORRECT ANSWER- ✔✔When the same molecule of treatment has
opposite effects on catabolic and anabolic pathways
What prevents gluconeogenesis from being a futile cycle? - CORRECT ANSWER- ✔✔The
inhibition of pyruvate kinase
Fermentation of pyruvate - CORRECT ANSWER- ✔✔is necessary to keep glycolysis
operating when oxygen is limiting.
