Gene mutation is :

Options

A. mutation in the genes of DNA
B. mutation in the chromosomes
C. mutation in the chromosomes
D. change in the sequence of nitrogenous bases

Answer

### Step-by-Step Solution:

1. **Definition of Gene Mutation**:
- Gene mutation refers to a sudden change in the genetic sequence of an organism. This change can affect the way genes function.

2. **Location of Mutation**:
- Mutations occur specifically in the DNA, which is the hereditary material in all living organisms.

3. **Structure of DNA**:
- DNA is organized into structures known as chromosomes. Each chromosome contains many genes.

4. **Genes and Their Composition**:
- A gene is a segment of DNA that contains the instructions for making a specific protein. Genes are made up of sequences of nucleotide bases.

5. **Nucleotide Bases**:
- The nucleotide bases consist of purines (adenine and guanine) and pyrimidines (cytosine and thymine). The sequence of these bases determines the genetic information.

6. **Types of Mutations**:
- Mutations can occur in various forms, such as point mutations (where a single nucleotide is changed) or frame shift mutations (where nucleotides are added or deleted, altering the reading frame of the genetic code).

7. **Example of a Mutation**:
- An example of a mutation is changing the sequence from GATTC to GTTC, where one nucleotide is lost. This type of mutation is classified as a frame shift mutation.

8. **Conclusion**:
- In summary, gene mutation is a change in the sequence of nucleotide bases in DNA, which can lead to changes in the function of the gene and potentially affect the organism's traits.