DNA segment cleaved by EcoRI is

Options

A. ATTCGA
TAAGCT
B. GAATTC
CTTAAG
C. GCTTAA
CGAATT
D. GTTCAA
CAAGTT

Answer

To determine the DNA segment cleaved by EcoRI, we need to follow these steps:

### Step-by-Step Solution:

1. **Understand EcoRI**: EcoRI is a restriction endonuclease that recognizes specific DNA sequences and cuts them. It is derived from the bacterium *Escherichia coli*.

2. **Identify the Recognition Sequence**: The specific sequence that EcoRI recognizes is a palindromic sequence. A palindromic sequence reads the same forward and backward on complementary strands.

3. **Know the Specific Sequence**: The recognition site for EcoRI is the sequence GAATTC. This means that when reading the DNA strand from the 5' to 3' direction, the sequence GAATTC will appear the same on the complementary strand when read from 3' to 5'.

4. **Analyze the Options**: If given multiple options, we need to check which of them is a palindrome. The sequence GAATTC is palindromic because:
- 5' GAATTC 3' (one strand)
- 3' CTTAAG 5' (complementary strand)

5. **Determine the Cut Site**: EcoRI cuts between the G and A on both strands, resulting in sticky ends that can be used in recombinant DNA technology.

6. **Select the Correct Answer**: Based on the analysis, the correct answer is the sequence GAATTC, as it is the only palindromic sequence that EcoRI recognizes and cleaves.

### Final Answer:
The DNA segment cleaved by EcoRI is **GAATTC**.

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