Telomeres with repetitive DNA sequence

Options

A. Act as replicons
B. Are transcription initiators
C. Help in chromosome pairing
D. Prevent chromossome loss

Answer

### Step-by-Step Solution:

1. **Understanding Telomeres**:
- Telomeres are the protective caps located at the ends of linear chromosomes. They consist of repetitive DNA sequences that do not code for proteins.

2. **Function of Telomeres**:
- The primary function of telomeres is to protect the chromosome from deterioration and prevent the ends of chromosomes from fusing with neighboring chromosomes. This is crucial for maintaining genetic stability.

3. **Impact of Cell Division**:
- Each time a cell divides, the telomeres shorten. This shortening occurs because the DNA replication machinery cannot completely replicate the very ends of linear chromosomes. Eventually, if telomeres become too short, the cell can no longer divide, leading to cellular aging or apoptosis.

4. **Resistance to Damage**:
- Telomeres are stable and resistant to exonuclease digestion, which means they can withstand certain enzymatic actions that could otherwise damage DNA.

5. **Evaluating Options**:
- Now, let’s evaluate the provided options:
- **Option 1: Act as replicons** - Incorrect, as telomeres do not function as replicons.
- **Option 2: Transcription initiators** - Incorrect, as telomeres do not initiate transcription.
- **Option 3: Helping chromosome pairing** - Incorrect, as telomeres prevent fusion with neighboring chromosomes rather than aiding pairing.
- **Option 4: Prevent the chromosome loss** - Correct, as telomeres prevent the loss of chromosomal ends and protect against damage.

6. **Conclusion**:
- The correct answer is **Option 4: Prevent the chromosome loss**.