Mutations

A gene mutation is a change in the sequence of bases that make up the gene

Three Causes of Mutations:

Errors in Replication× This occurs very rarely due to DNA

polymerase which proofreads the new strand to make sure it’s not missing a nucleotide/replaces false nucleotides

× 1 in 100, 000 nucleotides are added incorrectly

× 1 in 1, 000, 000, 000 pairs go unfixed

Three Causes of Mutations:

Mutagens× Environmental influences (mutagens)

cause mutations× Ex) radiation, X-rays, UV radiation,

organic chemicals (cigarettes, pesticides)

× DNA repair enzymes prevent drastic irregularities

Three Causes of Mutations:

TransposonsDNA sequences that are able to move within and between chromosomesTheir movement may alter nearby genes (alters their degree of expression)Studied in corn (purple kernels)Also known as Jumping genes

Note me: Inherited vs Developed

Why are some mutations inherited and some developed?

Germ line mutations: occur in reproductive cells (sperm and egg). Passed onto offspring.

Which heroes would be examples of Germ line mutations?

Note me: Inherited vs Developed

Somatic mutations: occur in body cells. NOT passed onto offspring. pring.

Which heroes would be examples of somatic mutations?

Note me: Inherited vs Developed

Somatic mutations: occur in body cells. NOT passed onto offspring. pring.

Which heroes would be examples of somatic mutations?

Note me: Inherited vs Developed

Two types of Mutations:

Frameshift MutationsWhen one or more nucleotides are deleted or inserted into the DNA (causes codons to shift)Ex) THE CAT ATE THE RAT without the C it reads…THE ATA TET HER AT

Why isn’t it THE AT ATE THE RAT?

Two types of Mutations:

Point Mutations

Two types of Mutations:

Point Mutations× Nucleotides are substituted for each

other× These may or may not cause major

changes× There are 3 different types of point

mutations

Point Mutations:

× Silent Mutation- If the C in UAC is substituted for a U we will get the combination UAU. UAC & UAU are both codons for the same amino acid (tyrosine)

× It causes no change to the protein created so it is “silent”

Point Mutations:

Nonsense Mutation- When a codon is turned into a stop codonUAC is changed to UAG (stop) it could cause dramatic changes

Point Mutations:

Missense Mutation- affects the shape of the protein.When synthesizing a hemoglobin amino acid chain, a valine amino acid is created instead of a glutamate amino acid. This causes the hemoglobin to have a sickle shape causing them to clog inside of vessels (Sickle Cell Disease)

Point Mutations:

Missense Mutation- affects the shape of the protein.

Note me: Sickle Cell Anemia

Missense Mutation- affects the shape of the protein.× This gene also gives a person

carrying it an increased resistance to malaria.

× It is believed that this gene persisted because it results in a greater resistance to a different and serious disease.

× MUTATIONS CAN ALSO BE GOOD!

Note me: Effects on Individuals

Loss – of – function mutations: mutations resulting in a protein product that has little or no normal function in the cell.

Gain-of-function mutations: the function gained may not be beneficial to the cell.

Note me: Effects on Individuals

Lethal mutations: mutations that are so damaging that the cell or organism dies as a result of its occurrence.

Morphological mutations: cause a change in the outward appearance of the cell or organism.

Example: Colour or shape of an organism.

Note me: Effects on Individuals

× Mutations are able to create new alleles/ phenotypes for genes

× This allows for genetic diversity

× Genetic diversity is important in maintaining biodiversity