Question

___________ are changes to the order of nucleotides in a segment of DNA that codes for a protein.

a. Proto-oncogenes

b. Tumor suppressor genes

c. Gene mutations

d. Negative regulators

Short answer

Gene mutations are changes to the order of nucleotides in a segment of DNA that codes for protein. The correct option is (c).

Step-by-step solution

Step 1. Introduction

A segment of DNA that codes for functional parts or proteins is known as genes.

Step 2. Explanation of Correct Option

A mutation leads to alterations in the sequence of DNA bases. Mutations may be caused by a variety of factors. Nevertheless, the nucleotide sequence of a protein-coding region of DNA is altered. Consequently, protein function is altered.

Thus, the correct option is - (c).

Step 3. Explanation of Incorrect Option

Proto-oncogenes are the genes that encode the positive cell-cycle regulators. What we call "proto-oncogenes" are genes that become oncogenes if they are mutated in the right manner. So, they do not change the order of nucleotides in a segment of DNA that codes for a protein.

Thus, option (a) is incorrect.

Several genes encode negative regulator proteins, which when activated, prohibit the cell from undertaking uncontrolled division. Those are known as tumour suppressor genes. So, they do not change the order of nucleotides in a segment of DNA that codes for a protein.

Thus, option (b) is incorrect.

Negative regulators are the second kind of cell-cycle regulator molecules. So, they do not change the order of nucleotides in a segment of DNA that codes for a protein.

Thus, option (d) is incorrect.