Question

4 parts | 0.25 of 1 point
a student has drawn an enlarged portion of a dna \ladder\ model to show two of the nucleotides in greater detail (in the same orientation as they would occur in the ladder model). which two nucleotides did the student draw?

1. a c

t g
t a
g c
a t

1. a c

c g
t a
g c
a t

1. a c

t g
t a
g c
a t

1. a c

t g
t a
g c
a t

Explanation:

1. First, identify the bases in the diagram: the larger double-ring structure is a purine (adenine, A, or guanine, G), and the smaller single-ring structure is a pyrimidine (cytosine, C, thymine, T).
2. Next, recall DNA base pairing rules: purines pair with pyrimidines, specifically adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).
3. Match this to the options: the only pair with a purine (A) and pyrimidine (C) that are complementary pair candidates (and match the structure orientation) is the first option.

Answer:

A. A, C
T, G
T, A
G, C
A, T