Question

1. In E. coli cell is grown in the presence of high amounts of glucose. Which of the following is true?

a. The cell will use lactose as a carbon source.

b. The level of cyclic AMP in the cell will be low.

c. The level of cyclic AMP in the cell will be high.

d. Transcription of mRNA from the lac operon will be high

e. The cell will die.

2. Enhancers are

a. proteins located adjacent to promoters

b. distant nucleotide sequences where gene regulatory proteins bind

c. nucleotide sequences that block replication and inhibit transcription

d. proteins that bind and deactivate repressors

e. bacterial forms of promoters

3. When tryptophan is present in the media, the tryptophan molecules regulating the trp operon binds the

a. trpE enzyme

b. trp promoter

c. trp operator

d. trp repressor

e. trp polymerase

4. Your liver and heart cells are different because

a. they contain different genes

b. they contain different operons

c. each contains unique promoters

d. different regulatory genes are expressed in different tissues

e. they contain different chromosomes

5. In prokaryotic cells, a group of genes that code for functionally related and coordinately regulated proteins is a(n)

a. exon

b. intron

c. operon

d. repressor

e. homopolymer

6. Heterochromatin corresponds to densely packed regions of chromosomes. Hence heterochromatin likely contains:

a. Methylated DNA and hypoacetylated nucleosomes.

b. Methylated DNA and hyperacetlyated nucleosomes.

c. Unmethylated DNA and hyperacetylated nucleosomes.

d. Unmethylated DNA and hypoacetylated nucleosomes.

e. Degraded DNA and degraded nucleosomes.

7. The I^s mutation yields a super repressor of the lac operon. The most likely cause of this phenotype is:

a. The operator region no longer binds I^s repressor.

b. The promoter element shows irreversible binding to the inducer, lactose.

c. The beta-galactosidase gene is active.

d. The I^s repressor protein can no longer bind the inducer lactose.

e. The I^s repressor binds ribosomes, blocking expression of the lac operon.

8. Attenuation is a form of transcription regulation

a. that can be manifested by coupling transcription and translation .

b. that permits the photolyase reaction to repair DNA during transcription.

c. that results in degradation of amino acids not essential to growth.

d. that yields progressive increases in disease severity with age.

e. that can only be manifested through trans-activation of adjacent operons.

9. Multi-cistronic (polycistronic) messenger RNAs

a. Are only found in eukaryotic cells and encode genes for the cistronic organelle.

b. Encode transfer RNAs found inside bacterial mitochondria.

c. Distinguish between splice variants during the constitutive growth phase.

d. Is a single messenger RNA encoding multiple, different gene products.

e. Encode a single polypeptide chain.

10. An insulator functions to

a. Insulate ribosomes from enhancer effects

b. Insulate mRNAs from exonuclease activity

c. Insulate cells from the effects of bacterial endotoxins

d. Insulate specific introns from splicing.

e. Insulate genes from the effects of an enhancer

Answer 1