DNA

• Chromosomes are really long molecules of DNA
• DNA stands for DeoxyriboNucleic Acid. It's the chemial that all of the genetic material in a cell is made up from
• DNA contains coded information - basically all the instructions to put an organism together and makes it work
• It's what's in your DNA that determines what inherited characteristics you have
• DNA is found in the nucleus of animal and plant cells, in really long structures called chromosomes
• Chromosomes normally come in pairs
• DNA is a polymer. It's made up of 2 strands coiled together in the shape of a double helix
• A gene codes for a specific protein
• A gene is a small section of DNA found on a chromosome
• Each gene codes for (tells the cells to make) a particular sequence of amino acids which are put together to make a specific protein
• Only 20 amino acids are used, but they make up thousands of differennt proteins
• Genes simply tell cells in what order to put the amino acids together
• DNA also determines what proteins the cell produces, e.g. haemoglobin, keratin. That in turn determines what type of cell it is, e.g. red blood cell, skin cell
• Every organism has a genome
• Genome is a term for the entire set of genetic material is an organism
• Scientists have worked out the comlete genome
• Understanding the human genome is a really important tool for science and medicine for many reasons
• Genomes allow scientists to identify genes in the genome that are linked to different types of diseases
• Knowing which genes are linked to inherited diseases could help us to understand them better and could help us develop effective treatments for them
• Scientists can look at genomes to trace the migration of certain populations of people around the world
• All modern humans are descended from a common ancestor who lived in Africa, but humans can now be found all over the planet
• The human genome is mostly identical in all individuals, but as different populations of people migrated away from Africa, they gradually developed small differences in their genomes
• By investigating differences in people's genomes, scientists can work out when new populations split off in a different direction and what root they took years ago