Quarter exam AP bio

which of the following is an example of post transcriptional control of gene expression?

• the binding of transcription factors to a promotor

• gene amplification contributing to cancer

• the addition of methyl groups to cytosine bases of DNA

• the removal of introns and alternative splicing of exons

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If a researcher moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the following processes would likely occur when the cell is exposed to lactose?

• The genes of the lac operon will be transcribed continuously.

  
  

• The inducer will no longer bind to the repressor.

  
  

• The operon will never be transcribed.

  
  

• The repressor will no longer bind to the operator.

Which of the following mechanisms is used to coordinate the expression of multiple, related genes in eukaryotic cells?

• Environmental signals enter the cell and bind directly to promoters.

  
  

• A single repressor is able to turn off several related genes.

  
  

• The genes are organized into a large operon, allowing them to be coordinately controlled as a single unit.

• A given gene may have multiple enhancers, but each enhancer is generally associated with only that gene and no other.

Which of the following functions are characteristic of general transcription factors in eukaryotes?

• They inhibit RNA polymerase binding to the promoter and begin transcribing.

  
  

• They usually lead to a high level of transcription even without additional specific transcription factors.

• They bind to sequences just after the start site of transcription.

  
  

• They bind to other proteins or to the TATA box.

In positive control of several sugar metabolism-related operons, the cAMP receptor protein (CRP) binds to DNA to stimulate transcription. Which of the following environmental conditions causes an increase in CRP activity in stimulating transcription?

• a decrease in glucose and an increase in cAMP

  
  

• an increase in glucose and an increase in cAMP

  
  

• a decrease in glucose and a decrease in the repressor

  
  

• an increase in glucose and a decrease in cAMP

Which of the following processes would result from a mutation that deactivates a regulatory gene of a repressible operon in an E. coli cell?

• continuous translation of the mRNA because of alteration of its structure

• irreversible binding of the repressor to the operator

• continuous transcription of the structural gene controlled by that regulator

• complete inhibition of transcription of the structural gene controlled by that regulator

Imagine that you've isolated a yeast mutant that contains histones resistant to acetylation. What phenotype would you predict for this mutant?

• The mutant will show decreased levels of gene expression.

  
  

• The mutant will show increased levels of gene expression.

  
  

• The mutant will grow rapidly.

  
  

• The mutant will require galactose for growth.

When taken up by a cell, which of the following molecules binds to a repressor so that the repressor no longer binds to the operator?

• corepressor

  
  

• repressor

  
  

• inducer

  
  

• promoter

For a repressible operon to be transcribed, which of the following conditions must occur?

• RNA polymerase must not occupy the promoter, and the repressor must be inactive.

  
  

• RNA polymerase must bind to the promoter, and the repressor must be inactive.

  
  

• RNA polymerase and the active repressor must be present.

  
  

• A corepressor must be present.

Which of the following statements best describes the characteristics of siRNA?

• Which of the following statements best describes the characteristics of siRNA?

  
  

• Which of the following statements best describes the characteristics of siRNA?

  
  

• a double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA

  
  

• a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor