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Consider the following facts about the s...

Consider the following facts about the salient features of structure of DNA.
(a.Backbone constituted by sugar-phosphate,
b.Anti-parallel polarity,
c.chains coiled in right-handed fashion,
d.Pitch of helix is 34 nm,
e.Distance between a base pair in helix is `0.34` nm) Which of the above statements are correct?

A

a,b,c,e

B

a,b,d,e

C

a,b,d

D

b,c,d

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Which of the following statements are related to the structure of double helical DNA ? I.The helix makes one complete spiral turn every 34 A. II. The diameter of the helix is 20 A III.The distance between adjacent nucleotide is 3.4 A. IV. Each strand of helix has a backbone made up of alternating ricbose sugar and phosphate . V. The two adjacent sugar molecules joined with phosphate by phosphodiester bond.

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Read the following five statements (A to E) about nucleic acids and select the option with all correct statements: (A) DNA is a long polymer of deoxyribonucleotides. (B) The two chains of DNA have anti-parallel polarity. (C) The backbone in a polynucleotide chain is formed due to nitrogenous bases and phosphates. (D) DNA acts as the genetic material in most of the organisms. (E) Uracil is present in RNA at the place of cytosine.

Read the passage given below and answer the question: EVIDENCE FOR THE FIBROUS NATURE OF DNA The basic chemical formula of DNA is now well established. As shown in Figure 1 it consists of a very long chain, the backbone of which is made up of alternate sugar and phosphate groups, joined together in regular 3' 5' phosphate di-ester linkages. To each sugar is attached a nitrogenous base, only four different kinds of which are commonly found in DNA. Two of these---adenine and guanine--- are purines, and the other two thymine and cytosine-are pyrimidines. A fifth base, 5-methyl cytosine, occurs in smaller amounts in certain organisms, and a sixth, 5-hydroxy-methyl-cytosine, is found instead of cytosine in the T even phages. It should be noted that the chain is unbranched, a consequence of the regular internucleotide linkage. On the other hand the sequence of the different nucleotides is, as far as can be ascertained, completely irregular. Thus, DNA has some features which are regular, and some which are irregular. A similar conception of the DNA molecule as a long thin fiber is obtained from physicochemical analysis involving sedimentation, diffusion, light scattering, and viscosity measurements. These techniques indicate that DNA is a very asymmetrical structure approximately 20 A wide and many thousands of angstroms long. Estimates of its molecular weight currently center between 5 xx 10^6 and 10^7 (approximately 3 xx10^4 nucleotides). Surprisingly each of these measurements tend to suggest that the DNA is relatively rigid, a puzzling finding in view of the large number of single bonds (5 per nucleotide) in the phosphate-sugar back bone. Recently these indirect inferences have been confirmed by electron microscopy. (source: Watson, J. D., & Crick, F.H. (1953, January). The structure of DNA. In Cold Spring Harbor symposia on quantitative biology (Vol. 18, pp. 123-131). Cold Spring Harbor Laboratory Press.) DNA has a _______ backbone

Read the passage given below and answer the question: EVIDENCE FOR THE FIBROUS NATURE OF DNA The basic chemical formula of DNA is now well established. As shown in Figure 1 it consists of a very long chain, the backbone of which is made up of alternate sugar and phosphate groups, joined together in regular 3' 5' phosphate di-ester linkages. To each sugar is attached a nitrogenous base, only four different kinds of which are commonly found in DNA. Two of these---adenine and guanine--- are purines, and the other two thymine and cytosine-are pyrimidines. A fifth base, 5-methyl cytosine, occurs in smaller amounts in certain organisms, and a sixth, 5-hydroxy-methyl-cytosine, is found instead of cytosine in the T even phages. It should be noted that the chain is unbranched, a consequence of the regular internucleotide linkage. On the other hand the sequence of the different nucleotides is, as far as can be ascertained, completely irregular. Thus, DNA has some features which are regular, and some which are irregular. A similar conception of the DNA molecule as a long thin fiber is obtained from physicochemical analysis involving sedimentation, diffusion, light scattering, and viscosity measurements. These techniques indicate that DNA is a very asymmetrical structure approximately 20 A wide and many thousands of angstroms long. Estimates of its molecular weight currently center between 5 xx 10^6 and 10^7 (approximately 3 xx10^4 nucleotides). Surprisingly each of these measurements tend to suggest that the DNA is relatively rigid, a puzzling finding in view of the large number of single bonds (5 per nucleotide) in the phosphate-sugar back bone. Recently these indirect inferences have been confirmed by electron microscopy. (source: Watson, J. D., & Crick, F.H. (1953, January). The structure of DNA. In Cold Spring Harbor symposia on quantitative biology (Vol. 18, pp. 123-131). Cold Spring Harbor Laboratory Press.) Out of the four different kinds of nitrogenous bases which are commonly found in DNA, _______ has been replaced in some organisms.

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