Question

Suppose that in Neurospora, an essential molecule is produced from precursors in the following pathway. The letters A, B, and C represent enzymes that are the products of genes a, b, and c. Answer if these statements are true of false.

Precursors --> int 1 --> int 2 -->essential molecule (With each arrow labeling a,b,c from precursor to essential molecule)

Indicate whether the following statement is true or false.

1. A mutant for gene a will grow on minimal medium + the essential molecule.

a) True

b)False

2. A wild type strain will grown on minimal medium.

a) True

b)False

3. A mutant for gene c will grow on minimal medium + intermediate 2.

a) True

b) False

4. A mutant for gene b will grow on mimal medium + intermediate 2.

a. True

b. False

Answer 1

Question 1:-

This statement is true.

Explanation:-

The mutant is gene A mutant, which means that this mutant can not convert Precursor to intermediate 1. So if we supply the minimal media with essential molecule, it doesn't need to use the pathway to synthesize the essential molecule and makes the whole pathway redundant.

Thus, it can grow on minimal media with Essential molecule.

Question 2:- Wild type

This statement is also TRUE.

Explanation:-

A minimal media is a media who don't not contain any amino acids or other extra nutrients. Thus they are used to grow and culture those microorganisms which do not have any mutations. These microorganisms' strain are called wild type.

So, a wild type is the one who can grow on minimal media without any added nutrients and it makes the statement true.

Question 3:- Gene C mutant.

This statement is FALSE.

Explanation:-

Now mutant for Gene C means that it can not convert the intermediate 2 into the essential molecule as that is the final step of the pathway and the enzyme made by Gene C catalyses that.

Since we are supplying this strain with Intermediate 2 molecule in the media, this mutant strain can not utilize this added nutrient because there's no enzyme in it for the conversion of Int 2 to essential molecule and that makes addition of this useless.

Question 4:- Gene B mutant

This statement is TRUE.

Explanation :

This mutant lack gene B and enzyme coded gene B is responsible for the conversion of intermediate 1 to intermediate 2. Now if we supply the intermediate in the media, this mean that it doesn't have to convert the Int 1 into Int 2, and it can directly convert intermediate 2 into essential molecule.

So this strain will grow on a minimal media supplied with Intermediate 2.