Chapter 15 Biology

Which of the following are types of post-transcriptional control of genes in eukaryotes?

• alternative RNA splicing or processing

• gene silencing through RNA interference

• destruction of ubiquitin tagged proteins

• all of the above

Which of the following is/are similarities between prokaryotic and eukaryotic gene expression?

• both use proteins to interact with the DNA to control gene expression

• both have histones complexed with their DNA

• both separate the processes of transcription and translation spatially

• all of the above

The tryptophan operon is a repressible operon that is

• turned off whenever tryptophan is added to the growth medium

• turned on only when glucose is present in the growth medium.

Transcription of the structural genes in an inducible operon

• occurs continuously in the cell.

• starts when the pathwayʹs substrate is present.

If you were to observe the activity of methylated DNA, you would expect it to

• be unwinding in preparation for protein synthesis.

• have turned off or slowed down the process of transcription.

This can inhibit transcription by blocking the binding of positively acting transcription factors to the DNA:

• enhancer

• promoter

• repressor

What does transformation involve in bacteria?

• the infection of cells by a phage DNA molecule

• assimilation of external DNA into a cell

Why is the transcription of structural genes of the trp operon turned off in the presence of tryptophan?

• Tryptophan is the repressor that binds to the operator, preventing transcription.

• The structural genes are used to make tryptophan, which would not be needed if tryptophan is available.

• Tryptophan has no effect on the transcription of the structural genes.

• Tryptophan RNA polymerase from finding the promoter of the trp operon, preventing structural gene transcription.

Which of the following statements regarding the trp operon is true?

• The operator region produces the mRNA that codes for the repressor.

• The regulatory gene is not transcribed in the presence of the repressor.

• Repressor proteins are inactivated by the presence of the repressor.

• The trp operon is always activated unless deactivated by a repressor

Most gene regulation happens at which step along the way?

• translation

• transcription

• signal transduction

• DNA replication