Inheritance, Genes & Chromosomes 2.0 / 5 based on 1 rating ? BiologyDNA and inheritanceIGCSEEdexcel Created by: Lucy SCreated on: 28-04-13 10:35 Inheritance Inheritance is the transfer of genetic information from generation to generation. 1 of 3 Genes A gene is a section of a DNA molecule that controls the development of certain characteristics. Genes are located on chromosomes. Genes control production of specific proteins in a cell. Different genes code for different physical characteristics. Each gene comes in at least 2 forms called alleles. Each allele codes for different forms of the same character. e.g. attached/unattached earlobes. Some alleles are dominant. (character they code for shows in appearance of individual, whether he/she inherits 1 or 2 of the alleles. Other alleles are recessive. (character they code for shows in appearance of individual only if allele is present on both chromosomes.) 2 of 3 Chromosomes Nucleus of a cell contains the chromosomes. Chromosomes are made up of DNA. Chromosomes are visible through a microscope during cell division. 46 chromosomes in nucleus of human cell. (diploid number). Each arranged as 23 matching (homologous) chromosomes. In 22 of the pairs both chromosomes are the same shape & size. 23rd pair are the sex chromosomes. The sex of a person is controlled by this pair of chromosomes, ** in females & XY in males. 3 of 3
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