140 likes | 323 Views
Chapter 12 DNA & RNA. Section 12 – 4 Mutations. Objectives. What are mutations?. Mutations. Key Concept : Gene mutations result from changes in a single gene. Chromosomal mutations involve changes in whole chromosomes. Gene Mutations. Point Mutations Affect one nucleotide
E N D
Chapter 12DNA & RNA Section 12 – 4Mutations
Objectives • What are mutations?
Mutations Key Concept:Gene mutations result from changes in a single gene. Chromosomal mutations involve changes in whole chromosomes
Gene Mutations • Point Mutations • Affect one nucleotide • Occur at a single point in the gene sequence • Three Types: • Deletion • Insertion • Substitution
Point Mutations Frameshift Mutations Result From Insertions & Deletions A nucleotide is added, or subtracted from the nucleotide sequence. This shifts the Codon grouping and drastically alters the amino acid sequence in the protein.
Insertion Mutation Deletion Mutation
Point Mutations Substitution A single nucleotide is changed in the nucleotide sequence. • This may result in a change to a single amino acid in the protein. • The change to a single amino acid may or may not alter the proteins function.
Chromosomal Mutations • Changes the number or structure of chromosomes • May change locations of genes on chromosome or the number of copies of some genes
Chromosomal Mutations 4 Types • Deletion • Duplication • Inversion • Translocation
Deletion X • Deletion • Loss of all or part of a chromosome
Duplication • Duplication • Segment of chromosome is repeated
Inversion • Inversion • Chromosome or part of a chromosome is oriented in the reverse direction
Translocation • Translocation • Part of one chromosome breaks off and attaches to another, • nonhomologous chromosome