Mutations 1 Base Mutations 2 Chromosomal Mutations What

Mutations 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 1. Base (Gene/small-scale) Mutations: -a change in DNA sequence (order of nucleotides). Types: a. POINT MUTATIONS (SUBSTITUTIONS) b. FRAMESHIFT MUTATIONS (DELETIONS/INSERTIONS) -

Point mutation (substitution)- change in one base pair in a DNA sequence -A point mutation 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 m. RNA Normal Protein Stop Replace G with A m. RNA Point mutation 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 Normal: ACT CCT 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. thly o. o d o s sm l cell ots. e v a o cl m m d r t o o o n like n se bl d ells ssels d cau c e kl od ve ck an c i S Sickle cells also can’t carry blo et stu h g g u s Oxygen as effectively as normal thro le cell k Cells. Sic

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 Delete this T ATA AAC CG

V. Frameshift mutation Deletion of U Frameshift mutation m. RNA Protein

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

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