3.16 DNA and Genetic Information

- Chromosomes are likely to contain thousands of genes
- When the gene loci is expanded, you will find a double helix (because there are two helixes) and they appear to be parallel
- Once the two strands of the helix is expanded you will see what is holding the two helixes together
- The sections on the outside are known as the "sugar - phosphate backbone"and in the centre there are a group of molecules called "Bases", the four different types of bases are: Adenine, thymine, eytosine and guanine
- In the molecules, these bases are holding together the two helixes. They are held together by the pairing between: Adenine and thymine on one side and cytosine and guanine. These are known as the "base pairs". They are gluing together one side of the DNA double helix with the other.
- The order of the bases: A-C-T-G-A-A-C-C-A-G, it is this order that we call the "gene"
- The gene is inside the nucleus. It is defined as the order of the bases (ATGC) and the number of the bases which codes for the construction of a protein in the cytoplasm.

a gene is the order of the bases on one side of the double helix