Practice Exam Flashcards
A reaction with a _____ Delta H and a ____ Delta S will never be spontaneous.
-positive, positive
-negative, positive
-negative, negative
-positive, negative
-none of the above
Positive, Negative
Which of the following functional groups has two hydrogen bond doners and one hydrogen bond acceptor?
-amide
-thiol
-amine
-alcohol
-ester
Amine
Urea is a water-soluble product of nitrogen metabolism. How many hydrogen bonds can one urea molecule donate to surrounding water molecules?
4
(2 amine groups)
Phosphoric acid is a polyprotic acid, with pK values of 2.14, 6.86, and 12.38. Which ionic form predominates at pH 9.3?
-H3PO4
-PO4-3
-H2PO4-1
-HPO4 -2
-none of the above
HPO4-2
Calculate the Delta G for a reaction with Delta H = 20 kJ/mol and S = 20 J/Kmol that is carried out at 27 degrees Celsius
14,000 J/mol
Which of the following is a function of the ribosome?
i. bind mRNA and allow codon recognition
ii. mediate the binding of proteins necessary for initiation, elongation, and termination
iii. catalyze synthesis of peptide bonds
iv. translocate such that multiple codons can be read
i, ii, iii, iv
Which of the following represents the correct order of steps in a PCR reaction beginning with double-stranded DNA?
-primer annealing, strand separation, primer extension
-primer annealing, primer extension, strand separation
-strand separation, primer extension, primer annealing
-strand separation, primer annealing, primer extension
-primer extension, primer annealing, strand separation
strand separation, primer annealing, primer extension
DNA sequencing using the Sanger method requires
-template, primer, DNA polymerase, mRNA, dNTPs
-template, primer, DNA polymerase, mRNA, dNTPs, ddNTPs
-template, primer, DNA polymerase, rRNA, dNTPs, ddNTPs
-template, primer, DNA polymerase, dNTPs, ddNTPs
-none of the above
template, primer, DNA polymerase, dNTPs, ddNTPs
At a pH above its pKa, the phenolic group of tyrosine is
-deprotonated and negatively charged
-protonated and neutral
-protonated and positively charged
-deprotonated and neutral
-none of the above
deprotonated and negatively charged
Which of the following tripeptides would be expected to be the most hydrophobic?
-KYA
-KYG
-DYA
-DYG
-GYA
GYA
Which of the following best describes the peptide backbone in a beta sheet?
-highly extended
-coiled
-compacted
-rigid
-none of the above
Highly extended
Enzyme X catalyzes the addition of a hydroxyl group to substrate Y. In the process, a metal cofactor is reduced and then reoxidized. What class of enzyme is X?
-hydroxylase
-oxidoreductase
-isomerase
-lyase
-ligase
Oxidoreductase
How does a catalyst increase the rate of a reaction?
-It increases the temperature of the reaction
-It makes the reaction more exergonic
-It causes a localized increase in the concentration of reactants
-It allows reacting molecules to more easily form the transition state
-None of the above
It allows reacting molecules to more easily form the transition state
A plot of velocity vs. substrate concentration for a simple enzyme-catalyzed reaction produces a _____. This indicates that at some point, the enzyme is ______.
-sigmoidal curve; inhibited by substrate
-hyperbolic curve; activated by substrate
-sigmoidal curve; saturated with substrate
-straight line; inhibited by product
-hyperbolic curve; saturated with substrate
hyperbolic curve; saturated with substrate
Which of the following must be TRUE if the steady state assumption is to be used?
-k1[E][S] = k2[ES]
-d[ES] / dt =0
-[E]T = [ES]
-k1[E]S[S] = k2 [ES] - k-1[ES]
-(k2-k-1) /k1 =1
d[ES] / dt =0
