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Science

Why organisms are different

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The genetic information passed from parent to offspring is contained in genes carried by chromosomes in the nucleus. Sexual reproduction produces offspring that resemble their parents, but are not identical to them.

Genetic information

Offspring resemble their parents because they contain genetic information passed on to them by their parents.

Chromosomes and genes

Chromosomes, found in the cell nucleus [nucleus: Controls what happens inside the cell. Chromosomes are structures found in the nucleus of most cells. ], contain many genes. A gene is a section of DNA [DNA: The material inside the nucleus of cells, carrying genetic information. DNA stands for Deoxyribonucleic Acid. ], which carries coding for a particular proteinproteins: organic compounds made up of amino acid molecules. One of the three main food groups, proteins are needed by the body for cell growth and repair.. Different genes control the development of different characteristics of an organism. Many genes are needed to carry all the genetic information for a whole organism.

chromosome, showing gene as section of DNA

Nucleus, chromosome and gene

The number of genes and chromosomes varies from species to species. For example, cells in human beings have 46 chromosomes that carry about 30,000 genes in each cell; and cells in fruit flies have 8 chromosomes that carry about 13,600 genes.

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