Mutations

What is a mutation? Changes in the genetic material

Mutations can occur in two different types of Cells: 1. Somatic (body) cells 2. Gamete (sex or germ) cells

Mutations in somatic cells Usually result in killing that body cell only. An exception to this is if the mutation occurs to the DNA that controls regulation of the cell cycle. This can result in cancer. Benign v. Malignant Somatic mutations usually do not affect the individual. Somatic mutations can NOT be passed on to the next generation.

Mutations that occur in Gametes: Gametes (sex or germ) cells Every cell of the developing fetus/baby will have that mutation Gamete mutations usually do affect the individual with some genetic disorder Gamete mutations can be passed on the next generation

Two Types of Mutations 2. Chromosomal Mutations 1. Gene Mutations A. Point Mutations B. Frameshift Mutations A. Deletion B. Duplication C. Inversion D. Translocation E. Non-disjunction

Gene Mutations: Small Scale Mutations Point Mutation Sickle cell hemoglobin is due to a single base substitution Example: usually effect no more than one amino acid THE FAT CAT ATE THE RAT THE FAT CAT ATE THE HAT

Sickle cell https://www.youtube.com/watch?v=1fN7rOwDyMQ

Frameshift Mutation A single nitrogen base is deleted or inserted from the DNA sequence causing a shift in the “reading frame” of the genetic message. Frameshift is usually more dramatic May change every amino acid that follows the point of insertion or deletion THE FAT CAT ATE THE RAT TEF ATC ATA TET HER AT

Chromosomal Mutations Deletion- loss of all or part of a chromosome Duplication-production of extra copies of parts of the chromosome Inversion- reverses the direction of parts of a chromosome Translocation- part of one chromosome breaks off and attaches to another chromosome Non-disjunction- means “not coming apart”. When homologous chromosomes fail to separate properly during meiosis (cell division producing gametes)

Chromosomal mutations: Large Scale mutations

Non-disjunction- Chromosomal mutation A karyotype generally has two chromosomes at each position (23 pairs) Trisomy (3) means a person has an extra chromosome Monosomy (1) means a person is missing a copy of a chromosome.

Trisomy 21- Down Syndrome Karyotype Notation? Sex?

Klinefelter’s Karyotype Notation? Sex?

Turner’s Syndrome Karyotype notation? Sex?

Mutations and Natural Selection Examine the diagram Does natural selection work on the genotype or phenotype? Natural selection leads to a change in the “population” NOT the individual.