If the first three nucleotides in 6bp palindromic sequence of one strand of a DNA molecule are CGT, what would be the next three nucleotides in the same strand most likely?

Options

A. TTC
B. ACG
C. CGT
D. TGC

Answer

To solve the question regarding the next three nucleotides in a 6bp palindromic sequence of DNA where the first three nucleotides are CGT, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Palindromic Sequences**:
- A palindromic sequence in DNA means that the sequence reads the same in both directions when considering the complementary strands. For example, if one strand is read from 5' to 3', the complementary strand will read the same from 3' to 5'.

2. **Identify the Given Sequence**:
- The first three nucleotides provided are CGT.

3. **Determine the Complementary Bases**:
- In DNA, the base pairing rules are as follows:
- Cytosine (C) pairs with Guanine (G)
- Guanine (G) pairs with Cytosine (C)
- Thymine (T) pairs with Adenine (A)
- Adenine (A) pairs with Thymine (T)

4. **Find the Complement for CGT**:
- For the sequence CGT:
- C pairs with G
- G pairs with C
- T pairs with A
- Therefore, the complementary sequence for CGT is GCA.

5. **Construct the Full Palindromic Sequence**:
- Since we need a total of 6 base pairs and we already have CGT, we can add the complementary bases we found:
- The complete palindromic sequence is CGT (first half) and ACG (second half).
- Thus, the full sequence reads: CGT ACG.

6. **Identify the Next Three Nucleotides**:
- The next three nucleotides in the same strand after CGT are ACG.

### Final Answer:
The next three nucleotides in the same strand are ACG.