dna one - chromosomes, genome & migration

• DNA


  Deoxyribonucleic acid, the chemical that all of our genetic material is made of
• DNA


  • DNA is a double helix polymer, which means it is a polymer made up of two strands forming a twisted, ladder shape.
• If you unraveled all the DNA in a single cell, the strand would be over two meters long
• Chromosome


  A really tight coil of DNA, there are 46 chromosomes in each of our cells
• There are only 23 different types of chromosomes, as we have two of each type (one from each parent)
• Sex chromosomes


  The 23rd pair of chromosomes, consisting of an X chromosome and a Y chromosome
• Females have two X chromosomes, while males have one X and one Y chromosome
• Chromosomes only look like an 'X' shape just before cell division, usually they look more like tight 'l' shaped coils
• Gene


  A gene is a small section of DNA. Genes code for a sequence of amino acids, which combine to give a specific protein.
• There are only 20 different types of amino acids, but they can be combined in many different sequences to form thousands of different proteins
• Genome


  The entire set of genetic material in an organism
• Scientists have now worked out the complete human genome, which allows them to identify genes linked to certain diseases
• Genomes can be used to trace the migrations of our ancestors by looking at small differences between populations