To determine the sequence of the complementary strand of DNA from the given sequence 5'-AGC-3', we need to use the concept of base pairing in DNA. DNA strands follow specific rules for complementary base pairing where:
- Adenine (A) pairs with Thymine (T)
- Cytosine (C) pairs with Guanine (G)
Here is a step-by-step solution:
1. Identify the given sequence:
The sequence provided is 5'-AGC-3'.
2. List the complementary base pairs:
- A (Adenine) pairs with T (Thymine)
- G (Guanine) pairs with C (Cytosine)
- C (Cytosine) pairs with G (Guanine)
3. Find the complements of each base in the given sequence:
- A is paired with T
- G is paired with C
- C is paired with G
4. Write out the complementary strand in the corresponding order:
- The complement of A is T
- The complement of G is C
- The complement of C is G
Thus, the complementary strand will be TCG.
5. Orient the complementary strand correctly:
DNA strands are always written from the 5' end to the 3' end. Since the complementary strand must also be from 5' to 3', we need to write the complementary sequence in reverse order so it matches the 5' to 3' direction.
The complementary sequence TCG, when reversed, becomes GCT.
6. Add the 5' and 3' labels:
Hence, the sequence of the complementary strand is 5'-GCT-3'.
Based on the explanation, the correct answer is:
5'-GCT-3'
