EcoRI always cut DNA molecules at a particular point by recognizing a specific sequence between :

Options

A. G and A
B. T and C
C. A and A
D. T and T

Answer

To solve the question regarding where EcoRI cuts DNA molecules, we will follow these steps:

### Step 1: Understand the Role of EcoRI
EcoRI is a restriction enzyme, also known as a restriction endonuclease, which is derived from the bacterium Escherichia coli. Its primary function is to cut DNA at specific sequences.

**Hint:** Remember that restriction enzymes are crucial tools in molecular biology for manipulating DNA.

### Step 2: Identify the Specific Sequence
EcoRI recognizes a specific palindromic DNA sequence. The sequence that EcoRI recognizes is 5’-GAATTC-3’. It cuts between the G and A nucleotides.

**Hint:** Look for palindromic sequences when studying restriction enzymes, as they often cut at these specific sites.

### Step 3: Determine the Cutting Point
EcoRI cuts the DNA strand between the G (guanine) and A (adenine) nucleotides, resulting in "sticky ends" or overhanging ends. This is important for cloning and recombinant DNA technology.

**Hint:** Sticky ends are useful for ligating DNA fragments together, so understanding where cuts are made is essential for genetic engineering.

### Step 4: Conclusion
Thus, EcoRI always cuts DNA molecules at the specific sequence between G and A.

**Final Answer:** EcoRI cuts DNA between G and A.

### Summary of Steps:
1. Recognize EcoRI as a restriction enzyme.
2. Identify the specific sequence it recognizes (5’-GAATTC-3’).
3. Note the cutting point between G and A.
4. Conclude that EcoRI cuts between G and A.