DNA replication is a simple and precise process that creates two complete strands of DNA (one for each daughter cell) where only one existed before (from the parent cell). Shortly before the cell begins to divide, its DNA within the nucleus is “unzipped” by a chemical called an enzyme which breaks the hydrogen bonds between the bases. Two halves of the DNA consequently exist. The free-floating nucleotides within the nucleus begin bonding to the bases of both strands. Because A only bonds with T and C only with G, both strands form exact matches. The two are identical.

Cell division, or mitosis (normal cell division; meiosis results in sex cells), occurs in four phases:

1. Prophase: The chromosomes pair up. By this time, the chromosomes have replicated so that the parent cell has two complete sets. The cell forms two poles and the nucleus disappears.

2. Metaphase: The chromosomes align at the equator between both poles.

3. Anaphase: The chromosomes divide, one of each copy heading toward each pole. The cell membrane begins to divide.

4. Telophase: Nuclei appear at either pole and the membrane divides. Two cells exist, each with identical chromosomes.

Genetic Basics

DNA Replication and Cell Division

Protein Synthesis

Genetic Basics Related Links