(i) Who provided the evidence of DNA as a genetic material?
(ii) Why is DNA called as polynucleotide?
(iii) List the three important features of double helical model of DNA.
Answers
Answer:
DNA is a long polymer and therefore, difficult to isolate from cells in an intact form. This is why it is difficult to study its structure. However, in 1953, James Watson and Francis revealed the ‘double helix’ model of the structure of DNA, based on X-ray diffraction data from Maurice Wilkins and Rosalind Franklin.
Deoxyribonucelic Acid (DNA) is the hereditary material found in the nucleus of eukaryotic cells (animal and plant) and the cytoplasm of prokaryotic cells (bacteria) that determines the composition of the organism.
Each spiral strand, composed of a sugar phosphate backbone and attached bases, is connected to a complementary strand by hydrogen bonding (non- covalent) between paired bases, adenine (A) with thymine (T) and guanine (G) with cytosine (C). It contains Deoxyribonucleic Acid It is double stranded.
Answer:
(i) Mendel.
(ii) DNA is made up many units of nucleotides.
(iii) Important features-
(a) Both the chains in helical runs anti-parallel.
(b) There two nitrogenous base Purine (A, G) and pyrimidine (T, C).
(c) A always bind with T and C always binds with G.