Self Quiz on Gene Regulation

1. The site on the DNA where proteins attach to influence whether transcription occurs is called

*    the operator

2. A protein binds to the operator region and prevents transcription.  This happens when a vitamin, required by the cell and made by the enzymes coded for by this operon, is plentiful in the cytoplasm.  What two words describe this type of regulation?

*    negative control of a repressible operon

3. The sequence of DNA recognized by the RNA polymerase as the place to start transcription is called

*    the promoter

4. Where in an operon would expect to find a stop codon such as UGA (in the DNA, TGA)?

*    UGA is a stop signal for translation, so it would be part of the sequence at the end of any of the genes in the operon; thus it could be present somewhere in the middle.

5. When glucose is present in the cell, what affect does this have on inducible operons for the use of other sugars?

*    glucose prevents the turning on of these operons

6. CRP is a regulatory protein that binds to what small signaling molecule?

*    cAMP

7. What role does active CRP play in the regulation of an operon?

*    positive control; it binds to the operator and promotes transcription

8. What codon in the mRNA marks the actual start of the information for making a protein?

*    AUG is always the first codon.

9. What is the function of the first several bases at the 5' end of a mRNA molecule?

*    the 5' end has a sequence that the ribosome attaches to for translation to begin

10. The actual molecule that binds to the lactose repressor protein to control transcription in the lac operon is

*    allolactose