Question

DNA is best described as (double/single) stranded, (parallel,antiparallel), and having the nucleotide composition of (A+T)/(C+G)=____ and (A+G)/(C+T)=____

A) Double; antiparallel; 1; 1
B) Double; parallel; 1; 1
C) Single; antiparallel; 1; 1
D) Single; parallel; 2; 1

Answer 1

DNA is a double-stranded, antiparallel molecule where adenine pairs with thymine and guanine pairs with cytosine, resulting in nucleotide composition ratios (A+T)/(C+G) and (A+G)/(C+T) both equal to 1.

Step-by-step explanation:

DNA Structure and Nucleotide Composition

DNA, or deoxyribonucleic acid, is a crucial molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses. DNA is best described as a double-stranded, antiparallel molecule, where the two strands are oriented in opposite directions to each other. Specifically, this means one strand runs in a 5' to 3' direction while the other runs 3' to 5'. The strands are held together by hydrogen bonds between complementary nucleotide bases, with adenine (A) always pairing with thymine (T) and guanine (G) pairing with cytosine (C).

Regarding the nucleotide composition, in a DNA molecule, the ratio of adenine to thymine and guanine to cytosine is always approximately 1:1, because these bases pair with each other specifically (A with T and G with C). Therefore, the nucleotide composition ratios (A+T)/(C+G) and (A+G)/(C+T) are both 1. So, the correct description of DNA considering the structure and nucleotide composition is option A) Double; antiparallel; 1; 1.