BIOLOGY Hard question

[299678]

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Which of the following types of enzymes are
usually subjected to direct feedback inhibition
by an intracellular metabolite?

(A) Enzymes catalyzing the last step in a
catabolic pathway
(B) Enzymes catalyzing the last step in a
biosynthetic pathway
(C) Enzymes catalyzing the first step in a
biosynthetic pathway
(D) Enzymes localized in the extracellular matrix
(E) Enzymes localized in lysosomes

Need Ur brief reasoning

 

[smiley89]

feedback inhibition occurs when the accumulation of products of a reaction inhibit earlier steps in that reaction. Therefore I would say C is the correct answer.

 

[Thundercatz]

Is the answer C?

It would a waste of time and energy to regulate the last step of a pathway.

A --> B --> C --> D--> E

Usually, if there was no more need for E, the end product (E) would signal A to stop the reaction (negative feedback).

If for some circumstance there was no need to produce E, and the cell wanted to stop the reaction, I think it would be more efficient to stop the first step of the process, saving energy.

I am not sure but good question!

 

[RCT PC CRN]

Answer is C

You want to minimize the use of Energy. Earlier you can stop is better.

 

[299678]

great ! thank you I didn't think about the energy part. It comes from one of GRE BIO questions. I need ur input for my other bio question