3.14

3.14 recall that the nucleus of a cell contains chromosomes on which genes are located

Chromosomes contain genetic information within a cell. In a typical cell, there is a nucleus with a number of chromosomes. They are composed of DNA and have the shape of double helix. Sections of the DNA are known as genes that contain information for construction of protein e.g. blood group, petal colour. Different organisms have different number of chromosomes e.g. Chicken 78, Humans 46, Cats 38 etc. The chromosomes operate in homologous pairs and the characteristics are based on the lengths of chromosomes. If we locate a gene (gene position: gene loci) and find the same position on the homologous pair, we find the same gene. There are two versions of each gene for one characteristics and these genes are called alleles.