Question

q 2. a section of dna is shown below, write the complementary dna strand
dna strand 1: 3 g c g t a c 5
dna strand 2: 5 ? ? ? ? ? ? 3

Explanation:

Step1: Recall base - pairing rules

In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).

Step2: Determine the complementary bases

For the given DNA strand 1: 3' - G C G T A C - 5', we find the complementary bases.

• G (in strand 1) pairs with C (in strand 2)
• C (in strand 1) pairs with G (in strand 2)
• G (in strand 1) pairs with C (in strand 2)
• T (in strand 1) pairs with A (in strand 2)
• A (in strand 1) pairs with T (in strand 2)
• C (in strand 1) pairs with G (in strand 2)

Step3: Reverse the orientation

Since strand 1 is 3' - 5', strand 2 should be 5' - 3'. So the complementary strand is 5' - C G C A T G - 3'

Answer:

5' - C G C A T G - 3'