Question

How many of the following statements about DNA are true? a. A-DNA and B-DNA form left-handed helices. b. G and C nucleotides base pair with three hydrogen bonds. c. The phosphodiester bonds that link adjacent nucleotides join the 3’hydroxyl of one nucleotide to the 5’ of the next. d. The two strands run in an antiparallel fashion. e. All monosaccharide units lack an –OH at C-2’

Answer 1

Answer:

the following are true

b. G and C nucleotides base pair with three hydrogen bonds.

c. The phosphodiester bonds that link adjacent nucleotides join the 3’hydroxyl of one nucleotide to the 5’ of the next.

d. The two strands run in an antiparallel fashion.

Explanation:

b. G and C nucleotides base pair with three hydrogen bonds.

G and C nucloetides join by 3 hydrogen bonfs while A and T have 2 hydrogen bonds between them.

c. The phosphodiester bonds that link adjacent nucleotides join the 3’hydroxyl of one nucleotide to the 5’ of the next.

phosphodiester bond is the linkage between the 3' carbon atom of one sugar molecule and the 5' carbon atom of another, deoxyribose in DNA.

d. The two strands run in an antiparallel fashion.

two strands are known be antiparallel  if they run parallel  to each other but opposite in direction. same in the case of DNA in which two strands which are complementary to each other  run parallel but opposite in direction i.e one from 5 to  3 and the other from 3 to 5 prime.