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In DNA the complementary bases are:
  • a)
    adenine and guanine; thymine and cytosine
  • b)
    adenine and thymine; guanine and cytosine
  • c)
    uracil and adenine; cytosine and guanine
  • d)
    adenine and thymine; guanine and uracil
Correct answer is option 'B'. Can you explain this answer?
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In DNA the complementary bases are:a)adenine and guanine; thymine and ...
Each nucleotide base can hydrogen-bond with a specific partner base in a process known as complementary base pairing: Cytosine forms three hydrogen bonds with guanine, and adenine forms two hydrogen bonds with thymine.
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In DNA the complementary bases are:a)adenine and guanine; thymine and ...
Complementary Bases in DNA

The nucleotides are the building blocks of DNA. They are composed of a nitrogenous base, a sugar molecule, and a phosphate group. The nitrogenous base is responsible for the genetic information that DNA holds. There are four nitrogenous bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G).

The complementary bases in DNA are pairs of nitrogenous bases that always bond together. The base pairing rules state that adenine (A) always pairs with thymine (T) and cytosine (C) always pairs with guanine (G). Therefore, the complementary bases in DNA are:


  • Adenine (A) and Thymine (T)

  • Cytosine (C) and Guanine (G)



This means that the amount of adenine in a DNA molecule is always equal to the amount of thymine, and the amount of cytosine is always equal to the amount of guanine. This is known as Chargaff's rule.

Significance of Complementary Bases

The complementary base pairing in DNA is very important for several reasons:


  • It ensures that the genetic information is accurately replicated during cell division.

  • It allows for DNA to be easily repaired if there is damage to one of the strands.

  • It provides a mechanism for DNA to be transcribed into RNA, which then directs the synthesis of proteins.



Conclusion

In conclusion, the complementary bases in DNA are adenine (A) and thymine (T), and cytosine (C) and guanine (G). The base pairing rules ensure that the genetic information in DNA is accurately replicated and transcribed, and allows for DNA to be easily repaired.
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Read the passage given below and answer the following questions:EVIDENCE FOR THE FIBROUS NATURE OF DNAThe 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 X106 and X107 (approximately 3 X104 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 nucleotid e) in the phosphate-sugar back bone. Recently these indirect inferences have been confirmed by electron microscopy.Q. Out of the four different kinds of nitrogenous bases which are commonly found in DNA, ___________ has been replaced in some organisms.

In DNA the complementary bases are:a)adenine and guanine; thymine and cytosineb)adenine and thymine; guanine and cytosinec)uracil and adenine; cytosine and guanined)adenine and thymine; guanine and uracilCorrect answer is option 'B'. Can you explain this answer?
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In DNA the complementary bases are:a)adenine and guanine; thymine and cytosineb)adenine and thymine; guanine and cytosinec)uracil and adenine; cytosine and guanined)adenine and thymine; guanine and uracilCorrect answer is option 'B'. Can you explain this answer? for Class 12 2024 is part of Class 12 preparation. The Question and answers have been prepared according to the Class 12 exam syllabus. Information about In DNA the complementary bases are:a)adenine and guanine; thymine and cytosineb)adenine and thymine; guanine and cytosinec)uracil and adenine; cytosine and guanined)adenine and thymine; guanine and uracilCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for Class 12 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In DNA the complementary bases are:a)adenine and guanine; thymine and cytosineb)adenine and thymine; guanine and cytosinec)uracil and adenine; cytosine and guanined)adenine and thymine; guanine and uracilCorrect answer is option 'B'. Can you explain this answer?.
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