Gene Mutations

Chapter 11

DNA and Chromosomes Prokaryotes:

DNA found in cytoplasm (no nucleus) as large, single molecule

Eukaryotes: DNA in nucleus on many

chromosomes (human = 46)

DNA length - 1,000x’s longer than cell diameter (must be folded)

Mutations Mutation: changes in genetic material Can occur on single gene, or entire

chromosome Causes:

1) Chance 2) Mutagens: factors that change DNA (i.e.: UV

light, cigarette tar, radiation, etc.)

Gene Mutations2 Types of Gene Mutations:

1) Point Mutations: occur at single point-may result in no change at all OR a genetic

disorder (sickle-cell anemia)

Substitution: 1or more nucleotides replaces another

a) Silent- doesn’t change the amino acidb) Missense- changes the amino acidc) Nonsense- changes amino acid to “stop”

Original DNA →

Mutated DNA →

THE DOG BIT THE CAT

THE DOG HIT THE CAT

THE DOG HIT THE CAR

THE GOG HIT THE CAR

Gene Mutations

2) Frameshift Mutations: shift in protein sequence; can ruin protein

-result is usually devastating

Insertion: 1or more nucleotides added

Deletion: 1or more nucleotides removed

Original DNA →

Mutated DNA →

Mutated DNA →

Original DNA →

THE DOG BIT THE CATTHE DOB ITT HEC AT