Deoxyribonucleic Acid (DNA)

DNA, or deoxyribonucleic acid, is the inherited material found in every single living creature. The deoxyribonucleic acid in an individual’s chromosomes controls a variety of visible characteristics and invisible characteristics. Visible characteristics include race, coloring and sex. An invisible characteristic includes blood groups and susceptibility to inherited diseases.

Deoxyribonucleic acid is made up of molecules called nucleotides. Each nucleotide contains a sugar group, a phosphate group, and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). Adenine and thymine are paired by two H bonds, whereas cytosine and guanine are paired by three H bonds.The Deoxyribonucleic acid is the same in all of the cells in the body of an individual.

DNA has a double helical structure. The outer edges are formed by alternating deoxyribose sugar molecules and phosphate groups, which make up the sugar-phosphate backbone. The two strands run in opposite directions.This means the nucleotides in each strand of DNA are exactly complementary to that in the other strand.The nitrogenous bases are positioned inside the helix structure.The bases, located inside the double helix, are stacked. The twists or turns in the two sugar-phosphate backbones of the double helix occurs every ten base pairs, which maximizes efficiency of the base-pair packing.

Consider the following statements.

  1. Deoxyribonucleic acid is the hereditary material found in almost all living organisms.
  2. It is made up of molecules called nucleotides.

Which of the following statements is/are correct?

  1. A) Only 1
  2. B) Only 2
  3. C) Both 1 and 2
  4. D) Neither 1 nor 2

Answer: C

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