DNA Replication and Mutation Types

DNA Replication

Process of copying DNA, not perfect.

Single Cell Organism Mutations

All daughter cells inherit mutations.

Multicellular Organism Mutations

Mutations can be somatic or germline.

Somatic Mutations

Passed to daughter cells in specific area.

Germline Mutations

Passed to new organisms through reproduction.

Wild Type

Non-mutated gene, typically functional.

Mutation Frequency

Eukaryotes: 1 mistake per billion nucleotides.

Proofreading

Exonuclease activity correcting DNA errors.

Mismatch Repair System

Identifies mismatches and hemimethylated DNA.

Methyl Directed Mismatch Repair (MMR)

Uses GATC sequence to identify errors.

Mut S

Scans DNA for mismatches.

Mut H

Cuts non-methylated strand at hemimethylated site.

Mut L

Activates single-strand break repair.

Error Frequency Increase

100x higher if MMR enzyme is absent.

Point Mutations

Alteration of one or two bases.

Chromosome Level Mutations

Involves thousands of bases, larger scale.

Base Substitution Types

Transition or transversion mutations.

Frameshift Mutation

Changes reading frame, not divisible by 3.

Same Sense Mutation

Codon changes but specifies same amino acid.

Nonsense Mutation

Creates premature stop codon, inactivates protein.

Missense Mutation

Changes codon for different amino acid.

Sickle Cell Anemia

Result of single amino acid change.

Phenylketonuria (PKU)

Caused by one amino acid change.

Ames Test

Tests if substance is mutagenic.

Chromosomal Mutations

Includes insertion, deletion, and translocation.

Diseases from Chromosomal Mutations

Includes Huntington's, hemophilia A, and more.