1) Base Mutations 2) Chromosomal Mutations

What Are Mutations? Changes in the nucleotide sequence of DNA May occur in autosomes (not inherited) May occur in sex chromosomes (inheritable)

Are Mutations Helpful or Harmful? happen regularly Almost all are neutral Mutations can be good as well as bad. A good mutation could lead to a change in a protein that allows an animal to run faster or see better. (Increase in genetic variation!) A bad mutation could lead to a change in a protein that causes a genetic disease such as Sickle Cell Anemia or Hemophilia.

Mutagens A mutagen is something that causes a mutation. (Carcinogens cause cancer) Ex: radiation, chemicals.

Types of Mutations Base (Gene/small-scale) Mutations: -a change in DNA sequence (order of nucleotides). Types: POINT MUTATIONS (SUBSTITUTIONS) FRAMESHIFT MUTATIONS (DELETIONS/INSERTIONS) -

Point mutation (substitution)- change in one base pair in a DNA sequence -A point mutation can cause an amino acid to change, which may change the structure of the protein being made. Example: AUG=Met AAG=Lys - one letter changed (the U to a A) and one amino acid changed (from methionine to lysine). -Can a point mutation occur without changing an amino acid? Yes! called a silent mutation -Point mutations, in general, have the least consequences. But there are some exceptions…

Picture of A Point Mutation mRNA Normal Protein Stop Replace G with A Point mutation mRNA Protein Stop

Point mutations in our lives! -Sickle cell anemia is a blood disease caused by a point mutation. -A single nucleotide is changed from “A” to “T” which causes the amino acid to change from glutamic acid to valine: Amino acids: Thr – Pro – Glu – Glu Normal: ACT CCT GAG GAG Sickle cell: ACT CCT GTG GAG Amino acids: Thr – Pro – Val – Glu

Point mutations in our lives! -People with sickle cell anemia often experience a lot of pain and swelling and have trouble exercising. through blood vessels like normal cells do. Sickle cells do not move smoothly Sickle cells get stuck and cause blood clots. Sickle cells also can’t carry Oxygen as effectively as normal Cells.

2. Frameshift mutation -Frameshift Mutation: Addition or deletion of nucleotides to a DNA sequence. -worse than a point mutation because it causes the entire DNA sequence to be shifted over, so many amino acids are affected! Example: DNA: ATT AAA CCG ATA AAC CG Delete this T

V. Frameshift mutation Deletion of U Frameshift mutation mRNA Protein

Frameshift Mutations Crohn’s Disease is caused by a frameshift mutation. It causes inflammation to the digestive tract.

2. Chromosome Mutations Changing the structure of a chromosome May Involve: Changing the structure of a chromosome The loss or gain of part of a chromosome, usually during cell division

Chromosome Mutations Four types: Deletion Inversion Translocation Duplication

Deletion Due to breakage A piece of a chromosome is lost during cell division

Inversion Chromosome segment breaks off Segment flips around backwards Segment reattaches

Duplication Occurs when a gene sequence is repeated

Translocation Involves two chromosomes NOT homologous Part of one chromosome is transferred to another chromosome

Questions: Is this a point mutation or a frameshift mutation? -It’s a point mutation because only one nucleotide changed!

Questions: THE CAT ATE THE RAT THE CAR ATE THE RAT Point or frameshift?

Questions THE DOG BIT THE CAT THE DOB ITT HEC AT Point or frameshift?