The sticky ends of a fragmented DNA molecule are made of

Options

A. (a) calcium salts
B. (b) endonuclease enzyme
C. (c) unpaired bases
D. (d) methyl groups

Explanation

To answer the question, "The sticky ends of a fragmented DNA molecule are made of," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding DNA Fragmentation**:
- DNA can be fragmented using restriction enzymes, which cut the DNA at specific sequences. This results in either blunt ends or sticky ends.

2. **Identifying Sticky Ends**:
- Sticky ends are created when the restriction enzyme cuts the DNA in such a way that it leaves overhanging sequences of unpaired bases. These overhangs are essential for the ligation process, allowing the DNA fragments to bind together.

3. **Analyzing the Options**:
- A. Calcium salts: These are not related to the structure of DNA ends.
- B. Endonuclease enzyme: This is the enzyme that cuts the DNA but does not form the sticky ends.
- C. Unpaired bases: This option refers to the overhanging sequences that are characteristic of sticky ends.
- D. Methyl groups: These are chemical modifications that can occur on DNA but do not constitute the structure of sticky ends.

4. **Conclusion**:
- The sticky ends of a fragmented DNA molecule are made of **C. Unpaired bases**. These unpaired bases allow for the easy ligation of DNA fragments.

### Final Answer:
C. Unpaired bases

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