DNA is found primarily in the nucleus of a cell in strands of genetic material called chromosomes. Each chromosome is a single piece of double stranded DNA; specific areas of the chromosome that are responsible for particular body functions are called genes.
The instructions coded by the 3-base sequences are actually carried to the areas in the cells where protein manufacture occurs by ribonucleic acid (RNA).
The structure (shape) and function of the thousands of proteins in an organism is controlled by the order of the amino acids in the protein, and therefore is ultimately controlled by the sequence of bases on the DNA. For example if one amino acid is substituted in the protein haemoglobin, the condition known as sickle cell anemia occurs, this condition is due to a single base change in the DNA that codes for this protein
When a cell divides the double stranded DNA is “unzipped”, and new DNA strands form using the single strands from the original DNA as templates thus replicating the sequence of DNA bases.
Many proteins and enzymes are involved in the process of DNA replication, one particular group the DNA polymerases are now used in the analysis of minute traces of DNA found at a crime scene as part of a technique known as POLYMERASE CHAIN REACTION (PCR).
