Molecular Genetics

Molecular Genetics

1. Maurice Wilkins observed that chromatin looks like beads on a string. This appearance is due to:
a. Ribosome synthesis
b. Condensation during cell division
c. The presence of histones
d. Supercoiling
e. None of the above

2. The following events occur during transcription. What is the third step?
a. RNA polymerase binds to the preinitiation complex
b. Transcription factor binds to the promoter
c. RNA polymerase unwinds the DNA
d. mRNA grows in the 5¹ -> 3¹ direction
e. The first nucleotide is added

3. Eukaryotic ribosomes consist of:
a. A 70S unit
b. 40S and 60S subunits
c. 30S and 50S subunits
d. A 100S unit
e. None of the above

4. The following steps occur during the elongation phase. The mRNA sequence is AUGUUC. Which is the third step?
a. A peptide bond is formed
b. tRNA(AAG) binds to the A site
c. tRNA(AAG) enters the P site
d. tRNA(UAC) leave the P site
e. tRNA(UAC) enters the P site

5. The antibiotic kasugamycin blocks binding of rRNA(Fmet). From this information you can conclude that kasugamycin:
a. Prevents polypeptide termination in eukaryotes
b. Prevents polypeptide elongation in eukaryotes
c. Prevents polypeptide initiation in prokaryotes
d. Prevents mRNA-ribosome binding in eukaryotes
e. Prevents mRNA-ribosome binding in prokaryotes

6. In eukaryotes, proteins synthesized on free ribosomes can be found in all of the following except:
a. Nucleus
b. Mitochondria
c. Plasma membrane
d. Chloroplasts
e. Peroxisomes

7. Which of the following pairs is mismatched?
a. DNA polymerase-makes a molecule of DNA from a DNA template
b. DNA polymerase-makes a molecule of RNA from an RNA template
c. DNA ligase-joins segments of DNA
d. Transposase-insertion of DNA segments into DNA
e. Spliceosome-removal of introns

8. The mechanism by which glucose inhibits the arabinose operon is:
a. Catabolic repression
b. Translation
c. DNA polymerase
d. Repression
e. Induction

9. The mechanism by which lactose controls the lactose operon is:
a. Catabolic repression
b. Translation
c. DNA polymerase
d. Repression
e. Induction

10. Genetic change in bacteria can be brought about by all of the following except:
a. Mutation
b. Conjugation
c. Transduction
d. Transformation
e. None of the above

11. Which of the following is not a product of transcription?
a. A new strand of DNA
b. rRNA
c. tRNA
d. mRNA
e. None of the above

12. Which of the following statements if false?
a. DNA polymerase joins nucleotides in one direction only
b. The leading strand of DNA is made continuously
c. The lagging strand of DNA is started by an RNA primer
d. DNA replication proceeds in one direction around the bacterial chromosome
e. Multiple replication forks are possible on a bacterial chromosome

13. What is the sequence of amino acids coded for by the following sequence of bases in a strand of DNA? TTAGCATTTCGA
a. Leu-ala-phe-arg
b. Asn-arg-lys-ala
c. Asn-cys-val-ser
d. Transcription would stop at the first codon
e. Can't tell

14. The damage caused by ultraviolet radiation is:
a. Never repaired
b. Repaired during transcription
c. Repaired during translation
d. Cut out and replaced
e. Repaired by DNA replication

15. An enzyme that cuts and seals DNA is:
a. RNA polymerase
b. DNA ligase
c. Restriction enzyme
d. Transposase
e. DNA polymerase