Chapter 20: Problem 18

Describe the structure of a DNA molecule and what the name \(D N A\) stands for.

Short Answer

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DNA, Deoxyribonucleic Acid, is built up of two anti-parallel chains of nucleotides, coiled around each other in the form of a double helix. Each nucleotide is composed of a deoxyribose sugar, a phosphate group, and a nitrogenous base. These bases (adenine, thymine, guanine, cytosine) pair up specifically, forming the 'rungs' of the DNA 'ladder' - adenine pairs with thymine and guanine pairs with cytosine.

Step by step solution

Defining DNA

DNA stands for Deoxyribonucleic Acid. It is the molecule responsible for carrying the genetic instructions for the development, functioning, growth, and reproduction of all known organisms and many viruses.

Describing the General Structure

The general structure of a DNA molecule is a double helix, similar in shape to a twisted ladder.

Describing the Components of DNA

DNA is composed of two chains of nucleotides coiled around each other, and each nucleotide consists of three parts: a deoxyribose sugar, a phosphate group, and a nitrogenous base.

The Connection of the Components

The backbone of the DNA chain is made from alternating phosphate and sugar residues, and the sugar in a nucleotide is joined to its adjacent nucleotide's phosphate group. The nitrogenous bases extend inward from the sugar-phosphate backbone and pair with bases on the other DNA chain, making the rungs of the 'twisted ladder'. The base pairing is always adenine with thymine, and guanine with cytosine.

The Double Helix Structure

The two DNA strands are anti-parallel, meaning they run in opposite directions. This allows the bases to pair up and form a ring-like structure. The specific pairing and structure of the double helix are the fundamental features that allow replication and translation of DNA.

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Describe the structure of a DNA molecule and what the name \(D N A\) stands for.

Short Answer

Step by step solution

Defining DNA

Describing the General Structure

Describing the Components of DNA

The Connection of the Components

The Double Helix Structure

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