Chapter 26.4, Problem 26.8P

(a)

Interpretation Introduction

Interpretation:

The complementary sequence of bases for each given DNA strand has to be written.

Concept Introduction:

Composition of nucleic acid: Nucleic acid is a polymer of nucleotides. Each nucleotide has three parts: a sugar, a nitrogenous base, and a phosphate group. Two nucleotides are joined by phosphate diester linkage where a free phosphate on 5’ carbon of one nucleotide and a free –OH group on 3’ carbon of another nucleotide.

Base pairing in DNA: The two strands of the DNA double helix run in the opposite directions- one in 5’ to 3’ direction and other from 3’ to 5’ direction. The hydrogen bonding between two strands enhances the stability of the DNA; where the alignment of hydrophobic nitrogenous bases in the interior and hydrophilic phosphate and sugar groups on the exterior also enhance the stability. Adenine and thymine gives a pair forming two hydrogen bonds and cytosine and guanine gives rise to another pair forming three hydrogen bonds.

Sugar: In both DNA and RNA, sugar portion is found. In DNA, the sugar is D-ribose, where at 2’hydroxyl group is absent and in RNA, the hydroxyl group is present at 2’.

Nitrogenous bases: Five types of nitrogenous bases (has unique one-letter code A, G, T, U, and C) are derived from two parent compounds called purine and pyrimidine. The purine derivatives are Adenine and Guanine are two fused nitrogen containing rings. The pyrimidine derivatives are Thymine, Cytosine, and Uracil are only one nitrogen containing six-membered ring.  Adenine, Guanine, Thymine, and Cytosine are the nitrogenous bases present in DNA. Adenine, Guanine, Cytosine and Uracil are the nitrogenous bases present in RNA.

(b)

Interpretation Introduction

Interpretation:

The complementary sequence of bases for each given DNA strand has to be written.

Concept Introduction:

Composition of nucleic acid: Nucleic acid is a polymer of nucleotides. Each nucleotide has three parts: a sugar, a nitrogenous base, and a phosphate group. Two nucleotides are joined by phosphate diester linkage where a free phosphate on 5’ carbon of one nucleotide and a free –OH group on 3’ carbon of another nucleotide.

Base pairing in DNA: The two strands of the DNA double helix run in the opposite directions- one in 5’ to 3’ direction and other from 3’ to 5’ direction. The hydrogen bonding between two strands enhances the stability of the DNA; where the alignment of hydrophobic nitrogenous bases in the interior and hydrophilic phosphate and sugar groups on the exterior also enhance the stability. Adenine and thymine gives a pair forming two hydrogen bonds and cytosine and guanine gives rise to another pair forming three hydrogen bonds.

Sugar: In both DNA and RNA, sugar portion is found. In DNA, the sugar is D-ribose, where at 2’hydroxyl group is absent and in RNA, the hydroxyl group is present at 2’.

Nitrogenous bases: Five types of nitrogenous bases (has unique one-letter code A, G, T, U, and C) are derived from two parent compounds called purine and pyrimidine. The purine derivatives are Adenine and Guanine are two fused nitrogen containing rings. The pyrimidine derivatives are Thymine, Cytosine, and Uracil are only one nitrogen containing six-membered ring.  Adenine, Guanine, Thymine, and Cytosine are the nitrogenous bases present in DNA. Adenine, Guanine, Cytosine and Uracil are the nitrogenous bases present in RNA.