3.14 chromosomes

1. The nucleus of a cell contains chromosomes on which genes are located. 
2. Chromosomes are the genetic information within cells 
3. The chromosome is composed of a molecule known as DNA
4. This forms a shape known as a double helix.
5. Sections of these molecules are called genes. 
6. one chromosome will possibly have thousands of genes. 
7. Each gene carries the information for the structure of the protein. 
8. The protein gives us the characteristics associated with the gene e.g. Blood Group
9. Different organisms have different no. of chromosomes e.g. cat=38, chicken=76, chimpanzee=42, human=46 per cell. 
10. The chromosomes work in pairs known as homologous pairs 
11. The homologous nature is based on the length of the chromosomes. 
12. Genes are located in the same places within the homologous pair, in the gene locii. 
13. We have 2 versions of each gene for one characteristic. These versions are called alleles.