mutations gene mutations change in the nucleotide sequence of a gene may only involve a single...

MutatioMutationsns

Gene Mutations

• Change in the nucleotide sequence of a gene

• May only involve a single nucleotide

• May be due to copying errors, chemicals, viruses, etc.

Types of Gene Mutations

• Include:–Point Mutations–Substitutions– Insertions–Deletions–Frameshift

Point Mutation

• Change of a single nucleotide

• Includes the deletion, insertion, or substitution of ONE nucleotide in a gene

AP Biology

When do mutationsaffect the nextgeneration?

Mutations Point mutations

single base change base-pair

substitution silent mutation

no amino acid change redundancy in code

Missense mutation change amino acid

Nonsense mutation change to stop codon

AP Biology

Point mutation leads to Sickle cell anemiaWhat kind of mutation?

Missense!

Point Mutation

•Sickle Cell disease is the result of one nucleotide substitution

• Occurs in the hemoglobin gene

AP Biology

Sickle cell anemia Primarily Africans

recessive inheritance pattern strikes 1 out of 400 African Americans

hydrophilicamino acid

hydrophobic amino acid

Frameshift Mutation

• Inserting or deleting one or more nucleotides

• Changes the “reading frame” like changing a sentence

•Proteins built incorrectly

AP Biology

Mutations Frameshift

shift in the reading frame

changes everything “downstream”

insertions adding base(s)

deletions losing base(s)

Where would this mutation cause the most change:

beginning or end of gene?

Frameshift Mutation

• Original:–The fat cat ate the wee rat.

• Frame Shift (“a” added):– The fat caa tet hew eer at.

Amino Acid Sequence Changed

Gene Mutation Animation

AP Biology

Deletion leads to Cystic fibrosis

loss of oneamino acid

delta F508

Cystic fibrosis is a disease passed down through families that causes thick, sticky mucus to build up in the lungs, digestive tract, and other areas of the body.

AP Biology

Hemophilia Individuals blood does not clot

normally.