Question

Which of the following general statements about the structure of DNA is true?
A. The hydrogen bonds connecting base pairs exist in a polar environment
B. Both major and minor grooves are formed between the phosphate sugar backbone
C. The same C and N atoms are present in each groove
D. The amount of energy required to break down the AT and GC pairs is same

Answer 1

Hint:
DNA is deoxyribonucleic acid. All the 23 pair chromosomes carry DNA. These are double-stranded coiled helices. These have two polypeptide strands. The model of DNA was given by Watson and Crick. X-Crystallography was used to identify the structure.

Complete step by step answer:
Human genome is a set of nucleic acids sequence in the case of humans which is encoded as DNA with all 23 pairs of chromosomes in cell nuclei. DNA is deoxyribonucleic acid. It is composed of two polynucleotide chains. These coils around each other forming a helix. It carries information about the genetic development, growth and functioning of an individual. These also carry the physical trait genes from the parents.
A DNA molecule has a sugar, phosphate and purine/pyrimidine group.
Major and minor grooves are formed amongst this helical structure. They are formed due to the antiparallel arrangement of base pairs.
Option A: The hydrogen bonds connecting base pairs exist in a polar environment: The adenine and thymine are linked by 2 hydrogen bonds and guanine and cytosine have 3 hydrogen bonds. The nitrogenous base has a hydrophobic nature. The phosphodiester bond of DNA is hydrophilic. So, due to different aquatic interactions, there exists a polar environment in which hydrogen bonds connect these two regions of hydrophobicity and hydrophilicity.
Option B: Both major and minor grooves are formed between the phosphate sugar backbone: The minor groove is between oxygen and nitrogen of two different base pairs while the major groove is opposite to them.
Option C: The same C and N atoms are present in each groove: The amount of C is always more than the N atoms.
Option D: The amount of energy required to break down the AT and GC pairs is the same: AT has two hydrogen bonds and GC has three hydrogen bonds so to break the GC bond, more energy is required.
So the answer is option A: The hydrogen bonds connecting base pairs exist in a polar environment.

Note:
Human genome is a complete set of nucleic acids sequences in humans which is encoded as DNA with all 23 pairs of chromosomes in cell nuclei. DNA is deoxyribonucleic acid. It is composed of two polynucleotide chains. These coils around each other forming a helix. It has a diameter of 2nm. The DNA differs at only 0.1% in the whole genome of the world.