AP Bio Gene Expression

If an mRNA molecule has introns and exons in it, where is it?

• At a ribosome
• In the nucleus
• In a prokaryotic cell
• could be in the nucleus or the ribosome

Which of the following helps to stabilize mRNA by inhibiting its degradation?

• 5' cap and poly-A tail

• splicesosomes

• TATA box

• introns

• RNA polymerase

The "on/off" switch for an operon is called the _________.

• promoter
• repressor
• operator
• gene

A protein that binds to the operator and blocks the RNA polymerase

• regulator
• repressor
• activator
• corepressor

What is the name of the binding site of RNA polymerase in eukaryotes?

• operator
• operon
• inducer
• promoter

What does the repressor protein do?

• Allows RNA polymerase to read the gene
• Prevents RNA polymerase from reading the gene
• Reads the gene
• Translates the gene

Operons are found in the cells of which of the following types of organisms?

• prokaryotes (bacteria)
• eukaryotes (plant and animals)
• animals only
• viruses

Repressible negative control is when when the gene is transcribed by the ____ of a specific molecule

• presence
• absence

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

• A corepressor must be present.

• RNA polymerase and the active repressor must be present.

• RNA polymerase must bind to the promoter, and the repressor must be inactive and not blocking the promoter region.

• RNA polymerase cannot be present, and the repressor must be inactive.

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.