GENES & ALLELES

==What does DNA actually do?== DNA is sometimes refereed to as the "code of life". This is because the sequence of bases in a DNA molecule can determine an organisms characteristics. Cells have specialized equipment that can read a DNA sequence and use it to piece together '''amino acids''' in order to make '''proteins'''. Essentially, DNA is the recipe book for our proteins. Proteins are the moving working parts of our cells and are responsible for virtually all cellular processes. Complex cells contain various compartments (called organelles) that perform various functions from generating cellular energy to processing and packing materials. It is actually the different proteins within each compartment that are responsible for these cellular activities. The complex interaction of thousands of different proteins within each cell is what makes them living. ==Gene== '''A specific sequence of bases that codes for a protein (made from amino acids) that determines a characteristic''' [image:http://i.imgur.com/bwZgAzwl.jpg?1] Some key ideas: *'''One gene codes for one protein'''. In some instances a protein will determine a single trait, however complex traits are often determined by the interaction of several proteins. *Each and every cell in our body contains our entire '''genome''' -the complete set of genes needed to code for all our characteristics. *Most of our DNA doesn't actually code for anything. The non-coding regions were originally called junk DNA but we now know it plays an important role in the organisation of DNA in the cell. ==Alelles== '''Alternative versions of a gene''' While we all carry genes for the same characteristics, some individuals will have slightly different versions of these genes. These alternative versions are usually very similar and differ only by a few bases. However, this small difference can be enough to effect the associated trait. For instance in the example below both individuals have a gene that determines hair shape. However, they each have a slightly different version of this gene (allele). One has the curly hair allele and the other has the straight hair allele. [image:http://i.imgur.com/EHyNGcUl.jpg]