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Chromosomes are made from DNA. Genes are short sections of DNA. Genetically identical cells are produced by a type of cell division called mitosis. In sexual reproduction, a male gamete fuses with a female gamete to produce a new cell. This is called fertilisation. Gametes are produced by a type of cell division called meiosis. They contain a single set of chromosomes, whereas body cells contain two sets of chromosomes.
DNA, genes and chromosomes
DNA
DNA [DNA: The material inside the nucleus of cells, carrying genetic information. DNA stands for Deoxyribonucleic Acid. ] (deoxyribose nucleic acid) molecules are large and complex. They carry the genetic code that determines the characteristics of a living thing.
Except for identical twins, each person’s DNA is unique. This is why people can be identified using DNA fingerprinting. DNA can be cut up and separated, forming a sort of 'bar code' that is different from one person to the next.
Genes
A gene [gene: The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell's chemistry - particularly protein production. ] is a short section of DNA. Each gene codes for a specific protein by specifying the order in which amino acids must be joined together.
Chromosomes
The cell’s nucleus contains chromosomes [chromosomes: Rod shaped bodies found in the nucleus of cells that contain genetic information (DNA). ] made from long DNA molecules.
The diagram shows the relationship between the cell, its nucleus, chromosomes in the nucleus, and genes.
Nucleus, chromosome and gene
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