Question

The base sequence of a segment of dna is shown. dna strand 1. 3 prime. g. c. g. t. a. c. 5 prime. dna strand 2. 5 prime. 3 prime. which base sequence correctly completes dna strand 2? a a t a c g t b g c g t a c c c g c a t g d t a t g c a

a) A A T A C G T
b) G C G T A C C C
c) G C A T G
d) T A T G C A

Answer 1

The correct sequence to complete DNA strand 2, opposite to '3'-GCGTAC-5', according to base pair rules, is '3'-CGCATG-5' (option c). This follows the base complementary rule where A pairs with T and G pairs with C.

Step-by-step explanation:

If DNA strand 1 is '3'-GCGTAC-5'', the base sequence that correctly completes DNA strand 2, which is opposite to DNA strand 1 and oriented '5'-3'', will be '3'-CGCATG-5''. This is because DNA strands are antiparallel and the nucleotides pair specifically: adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). Hence, we will follow the base complementary rule to determine the correct sequence.

In the options provided, the correct sequence would be '3'-CGCATG-5'', which corresponds to option c) GCATG, taking into account that we actually present it in the '5'-3'' direction as '5'-GCATGC-3'.

Answer 2

The complementary base sequence to DNA strand 1 '3'-GCGTAC-5'' is '5'-CGCATG-3'' following the base pairing rules. The correct sequence for DNA strand 2 that completes the original DNA segment is option c) G C A T G.

Step-by-step explanation:

The original question asks about the base sequence that correctly completes DNA strand 2 given the sequence of DNA strand 1. For DNA strand 1 with the sequence 3'-GCGTAC-5', the base pair rule dictates that guanine (G) pairs with cytosine (C), and adenine (A) pairs with thymine (T). Therefore, the complementary sequence for DNA strand 2, which runs antiparallel from 5' to 3', would be 5'-CGCATG-3'.

In the context of DNA replication and structure, it's important to remember that the two strands of DNA are antiparallel and complementary to each other. This means that each base on one strand dictates which base will pair with it on the opposite strand, with adenine (A) always pairing with thymine (T), and cytosine (C) always pairing with guanine (G). Given this, we can determine that the correct answer for the complementary sequence of DNA strand 2 is 'CGCATG', which is option c).