BCHM 307 Final Exam Actual Exam Questions with Correct

pg. 1 BCHM 307 Final Exam/ Actual Exam Questions with Correct Verified Answers- Latest Update – Rated A+

Which of the following describes the isomerization of citrate to isocitrate? - ANSWER - converts a tertiary alcohol, which cannot easily be oxidized, to a secondary alcohol that can be oxidized

What is the purpose of DNA helicase? - ANSWER - separation of double stranded DNA into single stranded DNA in front of DNA polymerase

Which of the following mutations would cause a bulge in the DNA backbone? - ANSWER - transversion mutation

What is the nucleophile in the DNA polymerase mechanism? - ANSWER - the 3' hydroxyl on the deoxyribose

During the first half of the chymotrypsin mechanism where the acyl-enzyme intermediate is formed, what role does His play? - ANSWER - general base then general acid

How many cytochrome c molecules are oxidized by Complex IV for each molecule of oxygen that is reduced - ANSWER - 4

Which of the following occurs when the catalytic subunit of ATP synthase is in the loose state? - ANSWER

• ADP and Pi bind

Why is the occasional production of the superoxide radical anion by complex IV of the electron transport chain problematic? - ANSWER - It is highly reactive and can damage nearby biomolecules.

Which of the following can happen when a photosynthetic pigment absorbs light? - ANSWER - energy is lost as heat 1 / 3

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• energy is given off as fluorescence
• exciton transfer to a neighboring pigment

If the reduction potential for NAD+ is -0.315 V and the reduction potential for oxygen is 0.815 V, what is the potential for the oxidation of NADH by oxygen? - ANSWER - 1.13 V

Which of the following transport systems is used in the inner mitochondrial membrane? IMS = intermembrane space - ANSWER - antiport of ADP from IMS to matrix and of ATP from matrix to IMS

The highest point in a reaction coordinate diagram represents _____. - ANSWER - the transition state

Of the following ions, which would be most likely to participate in metal ion catalysis? - ANSWER - Zn2+

An organic molecule that is tightly bound to an enzyme and participates in an enzyme catalyzed reaction is specifically referred to as a _____. - ANSWER - prosthetic group

Which of the following amino acids would be most likely found in the active site of an enzyme that uses acid-base catalysis? - ANSWER - His

The ability for an enzyme to pick out one particular substrate from the myriad of molecules floating around its environment is an example of _____. - ANSWER - specificity

How does a catalyst affect the overall deltaG of an endergonic reaction? - ANSWER - it has no effect

Which of the following is the most effective way to increase the rate of a biochemical reaction? - ANSWER - add a catalyst

How does a catalyst increase the rate of a reaction? - ANSWER - it allows reacting molecules to more easily form the transition state

Of all the species that enzymes bind, they are thought to bind most tightly to _____. - ANSWER - transition states 2 / 3

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Chymotrypsin catalyzes the hydrolysis of a peptide bond and is therefore categorized as a _____. - ANSWER - hydrolase

Chymotrypsin has a large specificity pocket to bind the aromatic amino acids while elastase has a very small specificity pocket meant to bind Ala or Gly. Which of the following amino acid substitutions changes the specificity pocket of chymotrypsin to that of elastase? (Try to figure this out based on amino acid structures rather than just looking it up!) - ANSWER - Gly -> Val

If the Asp in the chymotrypsin active site was mutated to another amino acid, which of the following would be considered an invisible mutation in that it is least likely to impact the function of the enzyme? - ANSWER - Asp → Glu

Zymogens are not enzymatically active because _____. - ANSWER - their active sites are distorted and incapable of enzymatic activity

The molecule chymotrypsinogen is known as a(n) _____. - ANSWER - zymogen

What three amino acids are found in the catalytic triad of chymotrypsin? - ANSWER - Asp, His, Ser

Conversion of factor X to factor Xa represents a(n) _____ form of activation; binding of antithrombin to thrombin represents a(n) _____ form of inhibition. - ANSWER - irreversible; reversible

An enzyme that forms a covalent bond with its substrate during the course of a reaction is considered to undergo _____. - ANSWER - covalent catalysis

Which protein in the blood is responsible for converting fibrinogen to fibrin? - ANSWER - thrombin

Different enzymes that catalyze the same reaction are known as _____. - ANSWER - isoenzymes

In an enzyme mechanism that generates a negative charge in the transition state, which of the following would be most effective to have in the active site of the enzyme? - ANSWER - transition metal cation

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