EcoRI always cuts DNA molecules at a particluar point by recognizing a specific restriction sequence, the sticky ends fromed after digestion have the sequence

Options

A. AATTC
B. TCCCA
C. AACTT
D. TTCAC

Answer

To solve the question regarding the sticky ends formed after EcoRI digestion of DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding EcoRI**:
- EcoRI is a restriction endonuclease enzyme that cuts DNA at a specific recognition sequence. It is derived from the bacterium E. coli.

**Hint**: Remember that restriction enzymes are used to cut DNA at specific sequences, which is crucial for genetic engineering.

2. **Identifying the Recognition Sequence**:
- The recognition sequence for EcoRI is **GAATTC**. This sequence is palindromic, meaning it reads the same forwards and backwards on complementary strands.

**Hint**: Palindromic sequences are important for the action of restriction enzymes; they allow the enzyme to cut both strands of DNA symmetrically.

3. **Cutting the DNA**:
- When EcoRI encounters the GAATTC sequence in double-stranded DNA, it makes a cut between the G and the A on each strand. This results in the formation of sticky ends.

**Hint**: Visualize the cutting action of the enzyme; it helps to understand how the sticky ends are formed.

4. **Formation of Sticky Ends**:
- After the cut, the sticky ends produced will have the following sequences:
- On one strand: **AATTC**
- On the complementary strand: **TTAA**

**Hint**: Sticky ends are important for ligation, as they can easily bind to complementary sequences of other DNA fragments.

5. **Conclusion**:
- Therefore, the sticky ends formed after EcoRI digestion will have the sequence **AATTC**.

**Hint**: Always check the options provided in the question to confirm that your answer matches one of them.

### Final Answer:
The sticky ends formed after EcoRI digestion have the sequence **AATTC**.