Mutations: Definition: Changes in DNA in an organism. These changes can be problematic, can be helpful, or can have no effect. Mutations are what DRIVES EVOLUTION.

Types of Mutations: Gene Mutation: This is a mutation that produce changes within a single gene. These mutations normally occur at one single point in the DNA strand and are called point mutations. There are four types of gene mutations: Substitutions Insertions Deletions

Gene Mutations: Substitutions Substitutions: A point mutation where one base is changed to another. Missence Mutation: When the mutation only affects one amino acid which only marginally affects the protein. Usually no affect or small effect on the organism. Silent Mutation: The mutation doesn’t affect the protein at all. Nonsence mutation: If the mutation forms a stop codon to stop the protein prematurely. Protein may no longer work.

Gene Mutations: Insertions and Deletions In an insertion or deletion mutation, a base is either added or deleted. This often has major affects on the protein because everything becomes shifted. These mutations are also known as Frame-shift mutations, Since they shift the entire sequence of the DNA to the left or right.

Insertion Example:

Chromosomal Mutations These mutations affect chromosome Number or structure of the chromosome, and involve more than the gene mutations. Often have major effects on the organism. There are four types of chromosomal Mutations: Deletion Duplication Inversion Translocation Monosomy or Trisomy- missing or extra entire chromosome due to nondisjuction during meiosis.

Chromosomal Mutations

Significance of Mutations Most mutations are neutral which means that they have little to no effect. Some mutations can have large effects and can cause genetic disorder. Some mutations can have positive effects for an organism. These organisms will survive better. This drives evolution. If the mutation occurs in germ cells, then these traits can be passed to offspring. When a mutation occurs where an organism has entire extra chromosomes, this is known as polyploidy.