Hind-II always cut DNA molecules at a particular point by recognising a specific sequence of six base pairs. This specific base sequence is known as the................ .

Answer

**Step-by-Step Solution:**

1. **Understanding Hind-II**: Hind-II is a type of restriction enzyme, also known as an endonuclease. These enzymes are responsible for cutting DNA at specific locations.

2. **Function of Restriction Enzymes**: Restriction enzymes cut DNA at particular sequences of nucleotides. They can be classified into two types: endonucleases, which cut within the DNA strand, and exonucleases, which cut at the ends of the DNA.

3. **Specificity of Hind-II**: Hind-II recognizes a specific sequence of six base pairs in the DNA. This specificity is crucial for its function as a restriction enzyme.

4. **Identifying the Sequence**: The specific base sequence recognized by Hind-II starts with the nucleotide sequence 5' G T, followed by a pyrimidine (either cytosine or thymine), then a purine (adenine or guanine), and ends with A and C. The complementary strand would have the sequence that pairs with this.

5. **Terminology**: The specific sequence of base pairs that Hind-II recognizes and cuts is referred to as the "recognition sequence."

**Final Answer**: The specific base sequence is known as the **recognition sequence**.

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