SAT II Biology M : Transcription

Study concepts, example questions & explanations for SAT II Biology M

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Example Questions

Example Question #1 : Transcription

What is the dividing structure that separates transcription from translation in a eukaryotic cell?

Possible Answers:

Cell membrane

Nuclear envelope

Mitochondrial matrix

Rough endoplasmic reticulum membrane

Smooth endoplasmic reticulum membrane

Correct answer:

Nuclear envelope

Explanation:

The nuclear envelope separates transcription from translation in a eukaryotic cell. Translation cannot occur until transcription is finished, which is the opposite of what occurs in a prokaryotic cell. In eukaryotic cells, transcription occurs in the nucleus where mRNA will be produced. Once mRNA is produced, it will exit the nucleus through pores and then proceed to be translated into protein in the cytoplasm.

Example Question #2 : Transcription

The trp operon is a repressible operon. Which of the following best describes this type of operon?

Possible Answers:

None are correct

The operon is usually off and has an inactive repressor

The operon is usually on and has an active repressor

The operon is usually off and has an active repressor

The operon is usually on and has an inactive repressor

Correct answer:

The operon is usually on and has an inactive repressor

Explanation:

With a repressible system, the operon is on, meaning the repressor is inactive. Repressible operons are the opposite of inducible operons, which are always off until their repressor is inactivated.

Example Question #3 : Transcription

The lac operon is an inducible operon. Which of the following best describes this type of operon?

Possible Answers:

The operon is usually on and has an active repressor

The operon is usually off and has an active repressor

The operon is usually on and has an inactive repressor

The operon is usually off and has an inactive repressor

None of these

Correct answer:

The operon is usually off and has an active repressor

Explanation:

With an inducible system, the operon is off, meaning its repressor is active, or actively repressing the system from turning on. Inducible operons are opposite to a repressible operon, which is always on until it is repressed.

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