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CHEM 301 Introduction to Biochemistry – exam bank questions and answers 2024 Athabasca University
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CHEM 301 Introduction toBiochemistry – exam bank questions
and answers 2024 Athabasca
University CHEM 301 Introduction to Biochemistry
– exam bank questions and answers
2024 Athabasca University
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
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