Mutations A mutation is a permanent change in the DNA or RNA sequence of a gene. There are two ways in which DNA can become mutated: 1.Mutations can be inherited. 2.Mutations can be acquired. Kinds of Mutations Gene mutations & Chromosomal mutations

Gene Mutations Mutations that produce changes in a single gene. Point Mutation A mutation that changes only one small area or one nucleotide in a gene. Point mutations include substitution, in which one base is changed to another, as well as insertions and deletions, in which a base is inserted or removed from the DNA sequence. Point Mutation This is a single change in one of the four nucleotide bases. An" A " might change to a" C " for example.

Substitutions swapping an A for a T in a gene for hemoglobin causes a serious disease called sickle cell anemia. Hemoglobin does the job of carrying oxygen around the body in the blood. In people with sickle cell anemia, the sequence of amino acids in hemoglobin is different, and so it doesn't work as well. Substitution, in which one base is changed to another

Deletions Part of the DNA sequence — anywhere from one nucleotide to a large section of DNA — is missing. Deletions can cause the cell to use the wrong amino acids to build the protein. Deletions can also shorten the protein. In some cases, a chunk of the protein will be left out. (Imagine leaving out the sugar in a cake recipe.) Many cases of muscular dystrophy are caused by deletions. Deletion Part of the DNA sequence is missing.

Insertion Extra DNA is added to the normal DNA sequence. Similar to deletions, addition of DNA sequence can cause the cell to use the wrong amino acids to build the protein or shorten the protein. In some cases, the protein will have extra amino acids, which could affect protein function. (Try to bake a loaf of bread by adding an improper ingredient, such as liver.) Insertion Extra nucleotides are added to the sequence.

Frameshift mutation In a frameshift mutation there may be an insertion or deletion of several base pairs causing a misreading of the mRNA during translation.

Chromosomal Mutations Chromosomes may break during replication, and parts of chromosomes may then rejoin incorrectly. Letters on the colored chromosomes distinguish segments and identify consequences of duplications, deletions, inversions, and translocations.

Mutagens An agent, such as a chemical, ultraviolet light, or a radioactive element, that can induce or increase the frequency of mutation in an organism.