3.14 Chromosomes

1.
- Chromosomes: are the genetic information within a cell
- Typical cell: a nucleus - when opened up, a number of chromosomes is found
- Chromosomes are composed of a molecule called DNA and this forms a shaped known as the "Double Helix"
- A section of this molecule are called "Genes" and one chromosome will have many genes (possibly thousands of genes)
- Each gene carries the information for the construction of a protein
- The protein gives us the characteristics associated with the gene, e.g. blood group - a gene controls the production of the protein which controls the production of the characteristic

2.
- Different organisms have different number of chromosomes (e.g. cat = 38, chicken = 78, chimp = 42, human = 46)
- Chromosomes are known to operate in pairs = homologous pairs
- The homologous nature is based on the length of the chromosomes
- If you go to the same "gene loci" on the homologous pair, you will find the same gene, therefore, we have two versions of each gene for one characteristic - these versions are called "Allels