The evolution of Mycobacterium bovis and the badger culling controversy
Mutations
However, sometimes changes to the DNA sequence occurs; for example the sequence is disrupted by the deletion or addition of nucleotides. This can just be single nucleotides, or it can be whole genes that are either lost or acquired. These changes to the DNA sequence are known as mutations. Mutations can have positive and negative effects. If the mutation involved a deletion or acquisition of genes that hinder an organisms survival, then it is unlikely this organism will survive to pass the mutation on. However if this mutation codes for a favourable trait, then it is likely this mutation will be passed on to the organisms offspring.
DNA: The Code for Life
DNA
All living things on this planet are known as organisms. Every organism is composed of groups of organs, which are made up of tissues, which in turn are made up of cells.
Every cell in your body contains DNA. DNA, short for deoxyribonucleic acid, is where all the genetic information of an organism is stored. It is composed of sequences of nucleotides (the DNA sequence). There are 4 types of nucleotide: adenine (A), thymine (T), cytosine (C) and guanine (G). Two strands of nucleotides join together by A pairing with T and C pairing with G:
Nucleotides act as the instructions to build different proteins; nucleotides are effectively the genetic code. Nucleotides are grouped into genes and each gene codes for a different protein product. The subunits of proteins are amino acids and a group of 3 specific nucleotides codes for every amino acid. Therefore the order of nucleotides within a gene acts as the instructions to build a specific protein product :
Each individuals DNA codes for a set of characters known as traits. This genetic material is passed on from one generation to the next, meaning traits are passed on from parent to offspring. Every organism contains a mix of DNA from its 2 parents and therefore displays a mix of traits.