Question

Complementary stand of DNA ATGCTTCA is:

• A. TACGAAGA
• B. TACGAAGT
• C. TAGCAACA
• D. TAGCTACT

Answer 1

The Correct Option is B

The question asks for the complementary strand of the given DNA sequence: ATGCTTCA. To solve this, we need to understand the base pairing rules of DNA:

• Adenine (A) pairs with Thymine (T)
• Thymine (T) pairs with Adenine (A)
• Cytosine (C) pairs with Guanine (G)
• Guanine (G) pairs with Cytosine (C)

Using these pairing rules, let's find the complementary sequence:

1. The first nucleotide is A; its complement is T.
2. The second nucleotide is T; its complement is A.
3. The third nucleotide is G; its complement is C.
4. The fourth nucleotide is C; its complement is G.
5. The fifth nucleotide is T; its complement is A.
6. The sixth nucleotide is T; its complement is A.
7. The seventh nucleotide is C; its complement is G.
8. The eighth nucleotide is A; its complement is T.

Therefore, the complementary strand of DNA is TACGAAGT.

Let's compare this with the given options:

1. TACGAAGA - Incorrect, as the final nucleotide should be T, not A.
2. TACGAAGT - Correct, because it matches our derived complementary sequence.
3. TAGCAACA - Incorrect, as the sequence differs significantly.
4. TAGCTACT - Incorrect, as the sequence does not match.

Thus, the correct answer is TACGAAGT, as it is the exact complementary strand of the given sequence.