3 What is a mutation? @A mutation is any change in a cell’s DNA@ A mutation can occur in an individual gene- results in a single changed protein- bacterial resistance to antibiotics is an example of a beneficial gene mutation
4 What is a mutation continued A mutation can occur in a chromosome- a chromosome contains many genes- chromosomal mutations affect manyproteinsExamples: Down SyndromeEdward’s SyndromeCri-du-Chat
5 What Causes Mutations?Can be caused by mutagens- a physical or chemical cause of mutation. Examples: UV light, radiation, drugs, and benzene.Mutagens are often also carcinogens – anything that causes cancerCan be natural, random events.- mutations occur in 1/100,000 DNA replicationsMutations do not have to be bad (evolution)
6 Gene Mutations 1. Point Mutations 2. Frameshift Mutations
7 Point Mutations Substitution @A single nucleotide is Can change one amino acid in a proteinMilk – MileGGACAATCA GGACCATCAproline -valine-serine proline-glycine-serine
8 Frameshift Mutations@A nucleotide is either inserted or deleted from a-all of the triplets from the point of mutation onward will be changed
9 Frameshift Mutations Insertion An insertion occurs when a nucleotide is added to a geneExample: A nucleotide is insertedThe fat cat ate the ratThe faa tca tat eth era t-the extra nucleotide shifts all of the triplets that follow
10 Frameshift Mutations Deletions A deletion occurs when a nucleotide is removed from a gene.Example: A nucleotide is removedThe fat cat ate the ratThf atc ata tet her at
13 Chromosomal Mutations Chromosomal mutations involve changes in the number or structure of chromosomes.
14 Chromosomal Mutations Deletion involves the loss of all or part of a chromosome.
15 Chromosomal Mutations Duplication produces an extra copy of all or part of a chromosome.
16 Chromosomal Mutations Inversion reverses the direction of parts of a chromosome.
17 Chromosomal Mutations Translocation occurs when part of one chromosome breaks off and attaches to another.
18 Harmful and Helpful Mutations The effects of mutations on genes vary widely. Some have little or no effect; and some produce beneficial variations. Some negatively disrupt gene function.@However, without mutations, organisms cannotMutations are the source of genetic variability in a species.
19 Harmful EffectsSome of the most harmful mutations are those that dramatically change protein structure or gene activity causing genetic disorders.Some cancers, for example, are the product of mutations that cause the uncontrolled growth of cells.
20 Harmful EffectsSickle cell disease is a disorder associated with changes in the shape of red blood cells. Normal red blood cells are round. Sickle cells appear long and pointed.@Sickle cell disease is caused by a point mutation in one of the polypeptides found in (the blood’s principal oxygen-carrying protein)
21 Beneficial EffectsMutations often produce proteins with new or altered functions that can be useful to organisms in different or changing environments.For example, mutations have helped many insects resist chemical pesticides.
22 Beneficial EffectsPlant and animal breeders often make use of “good” mutations.The condition in which an organism has extra sets of chromosomes is called polyploidy.