The lac operon is useful in

Question

Question 7 (1 point)

You are working with a transcription factor protein and genetically remove the only helix-turn-helix domain in it. What is likely to happen?

Question 7 options:

The transcription factor no longer works as it does not bind DNA

The transcription factor works more efficiently as HTH domains inhibit DNA binding

The transcription factor is unable to release DNA due to loss of HTH

The transcription factor does not interact with its co-activator.

Question 8 (1 point)

Under which of the following conditions would the lac operon be active.

Question 8 options:

low glucose, high lactose

high glucose, high lactose

low glucose, low lactose

high glucose, low lactose

The transcription factor no longer works as it does not bind DNA

The transcription factor works more efficiently as HTH domains inhibit DNA binding

The transcription factor is unable to release DNA due to loss of HTH

The transcription factor does not interact with its co-activator.

Explanation / Answer

Answers: -

1.option "A"-The transcription factor no longer works as it does not bind DNA.

Explanation: -The helix-turn-helix motif is a DNA-binding motif.

**The recognition and binding to DNA by helix-turn-helix proteins is done by the two helices, one occupying the N-terminal end of the motif, the other at the C-terminus.

**In most cases, such as in the Cro repressor, the second helix contributes most to DNA recognition, and hence it is often called the "recognition helix".

**It binds to the major groove of DNA through a series of hydrogen bonds and various Van der Waals interactions with exposed bases.

**The other helix stabilizes the interaction between protein and DNA, but does not play a particularly strong role in its recognition.

2.option- "A"-

low glucose, high lactose-

low glucose, high lactose-

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