Chpt 18 Pre-Quiz Eukaryotes

A scientist clones a regulatory gene that is involved in controlling the expression of other genes and discovers that the regulatory gene encodes an enzyme that acetylates histones. It is likely that this enzyme regulates gene expression by __________.

• causing looser packing of the chromatin at the target gene, thereby enhancing transcription

• causing looser packing of the chromatin at the target gene, thereby inhibiting transcription

• causing tighter packing of the chromatin at the target gene, thereby inhibiting transcription

• causing tighter packing of the chromatin at the target gene, thereby enhancing transcription

Enhancers __________.

• are found in eukaryotic genomes

• may be located thousands of base pairs away from the promoter

• may be located upstream or downstream from the genes they regulate

• increase the rate of transcription

• All of the listed responses are correct.

The expression of a gene located in a tightly coiled region of DNA can be promoted by __________.

• methylation of histone tails

• demethylation of DNA

• the arrival of the RNA polymerase

• histone acetylation

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

• the addition of methyl groups to cytosine bases of DNA

• the removal of introns and alternative splicing of exons

• the binding of transcription factors to a promoter

• the folding of DNA to form heterochromatin

Post-transcriptional controls of gene expression __________.

• can include changes to mRNA stability

• may involve regulation of mRNA splicing

• may involve changes to the rate at which an mRNA is translated

• can include translational controls

• All of the listed responses are correct.

Blocking gene expression in eukaryotes with microRNA strands is called RNA

• transcription.

• translation.

• interference.

• digestion.

In eukaryotes, functional mRNA molecules are made from

• introns spliced together after exons are removed.

• exons spliced together with introns.

• exons spliced together after introns are removed.

• long pieces of RNA shortened by the Dicer enzyme.

How is euchromatin different from heterochromatin?

• Heterochromatin is the more densley aranged chromatin that is found during mitosis and meiosis, while euchromatin is the more loosely arranged chromatin found throughout the nucleus in interphase.

• Both consist of the 10-nm fiber, which during interphase is more densely arranged in euchromatin, and more loosely arranged in heterochromatin.

• Both consist of the 10-nm fiber, which during interphase is more densely arraged in heterochromatin, and more loosley arranged in euchromatin.

• Heterochromatin is accessible to the enzymes responsible for transcribing genes, while euchromatin is not.

Muscle cells differ from nerve cells mainly because they

• express different genes.

• contain different genes.

• use different genetic codes.

• have unique ribosomes.

Which of the following processes destroys RNA molecules if they have a sequence complementary to the an introduced double stranded RNA?

• RNA interference

• RNA blocking

• RNA obstruction

• RNA disposal