1. Regulation of Gene Expression
Chapter 18
Regulation of Gene Expression
Questions prepared by
Louise Paquin McDaniel College

2. What does the operon model attempt to explain?
the coordinated control of gene expression in bacteria
bacterial resistance to antibiotics
how genes move between homologous regions of DNA
the mechanism of viral attachment to a host cell
horizontal transmission of plant viruses
Answer: a

3. At which stages of gene expression are bacteria usually regulated
At which stages of gene expression are bacteria usually regulated? Eukaryotes?

4. Gene Regulation Each of a group of bacterial cells has a mutation in its lac operon. Which of these will make it impossible for the cell to metabolize lactose?
mutation in lacZ (β-galactosidase gene)
mutation in lacI (cannot bind to operator)
mutation in operator (cannot bind repressor)
mutation in lacI (cannot bind inducer)
Answer: a

5. Operon What elements from the following list constitute a bacterial operon?
repressor gene
promoter
inducer
all of the above
Answer: b

6. Transcription Factors General transcription factors in eukaryotes are needed for all genes using the same RNA polymerase. What is the function of specific transcription factors? Of enhancers?

7. Approximately what proportion of the DNA in the human genome codes for proteins or functional RNA?
83%
46%
32%
13%
1.5%
Answer e

8. Alternative Products A specific gene is known to code for three different but related proteins. This could be due to which of the following?
premature mRNA degradation
alternative RNA splicing
use of different enhancers
protein degradation
differential transport
Answer: b

9. miRNA A given RNA transcript forms numerous hairpin loops that are cut (diced) to form short double-stranded noncoding sequences. How can these resulting strands affect gene expression?

10. Developmental Regulation In the development of a multicellular organism, differential gene expression is responsible for both differentiation and sequential regulation. Write a plausible hypothesis for how one of these could occur in the formation of the heart.

11. Embryo Formation Scientists showed that bicoid mRNA, and then its Bicoid protein, is normally found in highest concentrations in the fly’s anterior. Predict what would happen if Bicoid were injected at the posterior end.
Answer: Anterior structures would form at both ends.

12. Oncogenes Which of the following would not typically cause a proto-oncogene to become an oncogene?
gene suppression
translocation
amplification
point mutation
retroviral activation
Answer: a

13. Multistep Cancer Causation How does the multistep model of colorectal cancer illustrate how an individual might inherit a “predisposition” for a particular type of cancer?
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