Mitochondria and plastids are able to synthesise some of their proteins because they have

Options

A. DNA only
B. RNA only
C. DNA and ribosomes
D. RNA and ribosomes.

Explanation

**Step-by-Step Solution:**

1. **Identify the Organelles**: The question refers to mitochondria and plastids, which are important organelles found in cells. Mitochondria are present in both plant and animal cells, while plastids are primarily found in plant cells.

2. **Understand the Function**: Both mitochondria and plastids are known for their ability to produce energy and perform photosynthesis (in the case of plastids). They also have the capability to synthesize some of their own proteins.

3. **Key Components**: The ability of these organelles to synthesize proteins is due to the presence of specific components:
- **Circular DNA**: Both mitochondria and plastids contain their own circular DNA, which is similar to bacterial DNA. This allows them to code for some of their own proteins.
- **Ribosomes**: They also contain ribosomes, which are the sites of protein synthesis. The ribosomes in mitochondria and plastids are similar to those found in prokaryotic cells.

4. **Semi-Autonomous Nature**: Because of the presence of circular DNA and ribosomes, mitochondria and plastids are referred to as semi-autonomous organelles. This means they can independently produce some of their proteins, although they still rely on the cell for many other functions.

5. **Conclusion**: Therefore, the correct answer to the question is that mitochondria and plastids can synthesize some of their proteins because they have circular DNA and ribosomes.

**Final Answer**: Mitochondria and plastids are able to synthesize some of their proteins because they have circular DNA and ribosomes.

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