Restricito enzymes cut the strand of DNA a little away from the centre of the palindromic site, but between the same two bases on the opposite single stranded strand, these overhanging stretches formed on each strand are called __________

Options

A. Blunt ends
B. Stickly ends
C. Staggered end
D. Both (2) & (3)

Answer

To solve the question regarding the type of overhanging stretches formed on each strand of DNA after being cut by restriction enzymes, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of Restriction Enzymes**:
- Restriction enzymes are proteins that cut DNA at specific sequences known as restriction sites. These sites are often palindromic, meaning the sequence reads the same forwards and backwards on complementary strands.

2. **Identify the Palindromic Sequence**:
- For example, consider a palindromic sequence like:
- 5' - G A A T T C - 3'
- 3' - C T T A A G - 5'
- Here, the restriction enzyme will cut between specific bases in this sequence.

3. **Determine the Cut Location**:
- In the example given, the restriction enzyme EcoRI cuts between the bases G and A on one strand and between the same two bases on the opposite strand. This results in overhanging ends.

4. **Define the Overhanging Stretches**:
- The overhanging stretches formed after the cut are not even; instead, they are uneven because the cut does not occur at the same position on both strands.

5. **Classify the Ends**:
- The uneven ends created by the restriction enzyme are referred to as "sticky ends." These sticky ends can easily pair with complementary sequences of DNA, facilitating the ligation process in genetic engineering.

6. **Evaluate the Options**:
- Given the options:
- a) Blunt end
- b) Sticky end
- c) Tight end
- d) Both second and third
- Based on the understanding of the cuts made by restriction enzymes, the correct answer is "sticky end."

### Final Answer:
The overhanging stretches formed on each strand are called **sticky ends**.

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