Review Questions

Jung Choi; Mary Ann Clark; and Matthew Douglas

  1. The AUC and AUA codons in mRNA both specify isoleucine. What feature of the genetic code explains this?
  1. complementarity
  2. nonsense codons
  3. universality
  4. degeneracy

2. How many nucleotides are in 12 mRNA codons?

  1. 12
  2. 24
  3. 36
  4. 48

3. Which event contradicts the central dogma of molecular biology?

  1. Poly-A polymerase enzymes process mRNA in the nucleus.
  2. Endonuclease enzymes splice out and repair damaged DNA.
  3. Scientists use reverse transcriptase enzymes to make DNA from RNA.
  4. Codons specifying amino acids are degenerate and universal.

4. Which subunit of the E. coli polymerase confers specificity to transcription?

  1. α
  2. β
  3. β’
  4. σ

5. The -10 and -35 regions of prokaryotic promoters are called consensus sequences because ________.

  1. they are identical in all bacterial species
  2. they are similar in all bacterial species
  3. they exist in all organisms
  4. they have the same function in all organisms

6. Which feature of promoters can be found in both prokaryotes and eukaryotes?

  1. GC box
  2. TATA box
  3. octamer box
  4. -10 and -35 sequences

7. What transcripts will be most affected by low levels of α-amanitin?

  1. 18S and 28S rRNAs
  2. pre-mRNAs
  3. 5S rRNAs and tRNAs
  4. other small nuclear RNAs

8. How do enhancers and promoters differ?

  1. Enhancers bind transcription factors to silence gene expression, while promoters activate transcription.
  2. Enhancers increase the efficiency of gene expression, but are not essential for transcription. Promoter recognition is essential to transcription initiation.
  3. Promoters bind transcription factors to increase the efficiency of transcription. Enhancers bind RNA polymerases to initiate transcription.
  4. There is no difference. Both are transcription factor-binding sequences in DNA.

9. Which pre-mRNA processing step is important for initiating translation?

  1. poly-A tail
  2. RNA editing
  3. splicing
  4. 7-methylguanosine cap

10. What processing step enhances the stability of pre-tRNAs and pre-rRNAs?

  1. methylation
  2. nucleotide modification
  3. cleavage
  4. splicing

11. A scientist identifies a pre-mRNA with the following structure.

An illustration that has five blocks rotating Exon and Intron ending with Exon. Above the each of the five blocks are 100bp, 50pb, 75bp, 90pb, and 120bp.

What is the predicted size of the corresponding mature mRNA in base pairs (bp), excluding the 5’ cap and 3’ poly-A tail?

  1. 220bp
  2. 295bp
  3. 140bp
  4. 435bp

12. The RNA components of ribosomes are synthesized in the ________.

  1. cytoplasm
  2. nucleus
  3. nucleolus
  4. endoplasmic reticulum

13. In any given species, there are at least how many types of aminoacyl tRNA synthetases?

  1. 20
  2. 40
  3. 100
  4. 200

14. A scientist introduces a mutation that makes the 60S ribosomal subunit nonfunctional in a human cell line. What would be the predicted effect on translation?

  1. Translation stalls after the initiation AUG codon is identified.
  2. The ribosome cannot catalyze the formation of peptide bonds between the tRNAs in the A and P sites.
  3. The ribosome cannot interact with mRNAs.
  4. tRNAs cannot exit the E site of the ribosome.

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Review Questions by Jung Choi; Mary Ann Clark; and Matthew Douglas is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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