Deoxyribonucleic acid (DNA)

Definition

Deoxyribonucleic acid (DNA) is a molecule that carries the genetic instructions for life. It is composed of two strands forming a double helix, with each strand made up of nucleotides containing a phosphate group, a sugar molecule, and a nitrogenous base.

5 Must Know Facts For Your Next Test

1. DNA's structure was discovered by James Watson and Francis Crick in 1953.
2. The four nitrogenous bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).
3. Adenine pairs with thymine via two hydrogen bonds, while cytosine pairs with guanine via three hydrogen bonds.
4. DNA replication is semi-conservative, meaning each new DNA molecule consists of one old strand and one new strand.
5. The sequence of nucleotides in DNA determines the genetic information carried by an organism.

Review Questions

• What are the components of a nucleotide in DNA?
• How do adenine and thymine pair together in the DNA structure?
• What does it mean that DNA replication is semi-conservative?

Related terms

Nucleotide:

A building block of DNA consisting of a phosphate group, a sugar molecule, and a nitrogenous base.

Double Helix:

The spiral structure formed by two strands of DNA held together by hydrogen bonds between paired bases.

Genome:

The complete set of genetic material present in an organism or cell.