Which one of the following is the complementary sequence of 5’TTAAGCTAC3′?
**Core Concept**
The complementary sequence of a DNA strand is determined by the base pairing rules: adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). This concept is essential for understanding DNA replication, transcription, and other genetic processes.
**Why the Correct Answer is Right**
To find the complementary sequence, we start with the 5' end of the given strand: TTAAGCTAC. We pair each nucleotide with its complement:
- T pairs with A
- T pairs with A
- A pairs with T
- A pairs with T
- G pairs with C
- C pairs with G
- T pairs with A
- A pairs with T
- C pairs with G
The complementary sequence is **AATTCGCTAG**, which is the correct answer.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not follow the base pairing rules.
**Option B:** This option is incorrect as it does not pair adenine with thymine and guanine with cytosine.
**Option C:** This option is incorrect as it does not correctly pair the nucleotides.
**Clinical Pearl / High-Yield Fact**
Remember the base pairing rules (A-T and G-C) to determine the complementary sequence of a DNA strand, which is crucial for understanding DNA replication and transcription.
**Correct Answer:** C. AATTCGCTAG