120 likes | 271 Views
Chapter 12 DNA & RNA. Section 12 – 4 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
E N D
Chapter 12DNA & RNA Section 12 – 4Mutations
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.
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