BIOCHEM MODULE 1 EXAM QUESTIONS AND
CORRECT ANSWERS | ALREADY GRADED A+ |
VERIFIED ANSWERS | LATEST VERSION (JUST
RELEASED)
Which of the following statements about α-keratins is FALSE?
A) They include a major class of protein that comprises hair, fingernails and
animal skin.
B) Individual molecules are α-helical.
C) There is a strip of contiguous hydrophobic surface making a shallow
spiral around the helix.
D) They include a small globular regions covalently linked to the surface.
E) Pairs of α-helices twist about each other in a coiled-coil structure held
together entirely by hydrophobic interactions ------CORRECT ANSWER-----
----------E) Pairs of α-helices twist about each other in a coiled-coil structure
held together entirely by hydrophobic interactions
The protein that makes up about a third of the total protein mass in animals
is:
A) β-keratin.
B) collagen.
C) hemoglobin.
D) myoglobin.
E) α-keratin ------CORRECT ANSWER---------------B) collagen.
Fibroin is a β-sheet protein, with a high proportion of glycine ------
CORRECT ANSWER---------------True
Tropocollagen is a double helix of two left-handed polypeptide chains ------
CORRECT ANSWER---------------False
,Scurvy results in weakness in collagen fibres because the enzymes that
catalyze ________ of proline and lysine residues in collagen require
Vitamin C ------CORRECT ANSWER---------------hydroxylation
Which of the following is CORRECT when considering the tertiary structure
of globular proteins?
A) β sheets are usually twisted or wrapped into barrel structures.
B) Hydrophobic residues are normally on the inside and hydrophilic
residues are on the outside.
C) The amino acid proline never occurs in a region where the polypeptide
chain bends or turns.
D) All parts of the proteins can be classified as helix, β sheet or turns.
E) None of the above ------CORRECT ANSWER---------------B) Hydrophobic
residues are normally on the inside and hydrophilic residues are on the
outside.
Proteins cannot self-assemble into a functional conformation after they
have been denatured ------CORRECT ANSWER---------------False
Protein folding is a random process, whereby a vast number of possible
conformations are tested to find the desired most stable state ------
CORRECT ANSWER---------------False
The folded conformation of proteins can be stabilized by the binding of a
metal ion or cofactor ------CORRECT ANSWER---------------True
The interactions that stabilize multisubunit complexes are different to those
that stabilize tertiary structure ------CORRECT ANSWER---------------False
,Protein folding is a thermodynamically favorable process under
physiological conditions because:
A) there is an increase in entropy associated with protein folding.
B) there is a decrease in entropy of the solvent by burying hydrophobic
groups within the molecule.
C) of the large negative enthalpy change associated with many
noncovalent interactions.
D) no intermediate stage disulphide bonds form during the folding process.
E) all of the above ------CORRECT ANSWER---------------C) of the large
negative enthalpy change associated with many noncovalent interactions.
The cavity in the GroEL-GroES complex from E. coli provides a favorable
environment that prevents ________ and mis-folding ------CORRECT
ANSWER---------------aggregation
Bovine spongiform encephalopathy is an infectious disease caused by a
prion protein, which undergoes a ________ change to become pathogenic
------CORRECT ANSWER---------------conformational
Proteins have an asymmetrical tertiary structure, while multisubunit
proteins can exhibit several types of symmetry ------CORRECT ANSWER---
------------True
The functional organization of proteins where specific complexes of two or
more polypeptides are formed is called ________ structure ------CORRECT
ANSWER---------------quaternary
, Which of the following produces the largest number of reducing equivalents
when oxidized?
A) Glucose
B) NADPH
C) NADH
D) Palmitic acid
E) A hydrogen atom ------CORRECT ANSWER---------------D) Palmitic acid
ATP has a high phosphoryl group transfer potential because:
A) it is chemically unstable.
B) it has a high rate of spontaneous hydrolysis at physiological pH and
temperature.
C) it exhibits resonance stabilization prior to hydrolysis.
D) it has three phosphate groups.
E) cleavage of either of its two phosphoanhydride bonds proceeds with a
large negative △Go' of hydrolysis ------CORRECT ANSWER---------------E)
cleavage of either of its two phosphoanhydride bonds proceeds with a large
negative △Go' of hydrolysis
Substrate-level phosphorylation is a term given to the loss of free energy
when ATP is hydrolyzed. ------CORRECT ANSWER---------------False
The main energy-coupling compound in biochemical reactions that allows
thermodynamically unfavorable processes to become favorable is
________. ------CORRECT ANSWER---------------ATP
Under physiological conditions the complete oxidation of glucose to carbon
dioxide and water in the presence of oxygen has a △G of -2900 kJ/mol
glucose. This process can be coupled to the synthesis of ~32 mol ATP.
The △G of the coupled reactions to make ATP is -1300 kJ/mol glucose.
Calculate the △G for the synthesis of ATP from ADP ------CORRECT
ANSWER---------------+50kJmol^-1
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