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

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

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

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

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

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?

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

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

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?

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.

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.

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

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? [comp: insert Clickers_C18_Slide13.jpg here]