AP Biology Topic 6.5 Gene Expression and Regulation

What are transcription factors?

• Molecules that provide ATP to transcription unit

• Molecules that synthesize RNA during transcription 

• Molecules that bring amino acids to the transcription unit

• Molecules that bind to enhance/inhibit transcription. 

 If the repressor is bound to the operator…

• RNA polymerase is able to bind; the operon is off

• RNA polymerase is able to bind; the operon is on

• RNA polymerase is unable to bind; the operon is off

• RNA polymerase is unable to bind; the operon is on

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

• only prokaryotes

• only eukaryotes

• animals, but not plants

• plants, but not animals

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

• regulatory gene

• enhancer

• operator

• repressor

A protein that binds to the operator and blocks RNA polymerase from transcribing the gene

• inducer

• repressor

• activator

• promoter

In the lac operon model, the genes within the operon will be expressed only if... (recall: it is an inducible operon)

• lactose is absent in the cell

• glucose is present in the cell

• lactose is present in the cell

• tryptophan is present

The lac operon is referred to as a(n) __________ operon because transcription is normally "off" unless lactose is present to turn "on" transcription of the genes by binding to and thereby removing the repressor.

• inducible

• repressible

What is the name of the stretch of DNA on an operon where RNA polymerase binds to initiate transcription?

• operator

• promoter

• enhancer

• origin

In eukaryotes, proteins that help the RNA polymerase bind to the promoter for transcription

• transcription factors
• topoisomerase
• regulatory genes
• activators

How can a person's muscle cells have the same exact DNA sequences as their nerve cells even though the look and perform completely different?

• The two different cells become mutated
• The proteins expressed in each cell are different
• They actually have different DNA in the two types of cells.
• The genome of the different cells changes

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