Mutation

Causes

Definition: a heritable change in DNA sequence of an organism

Mutagen

A chemical substance or radiation that can cause induced mutation

Spontaneous mutations can happen if mistakes occur during the DNA replication process

Chemical Mutagens

Radiation

Nucleoside analog: similar to nucleotide bases and can replace them but with different base-pairing rules, causing mutation

Other chemicals can alter the normal base pairs to have different rules

Intercalating agents: distorts the spacing between base pairs, causing DNA polymerase to skip or insert nucleotides during DNA replication

Ionizing radiation can:

  • cause breaks in the DNA backbone by forming radicals
  • modify bases

Non-ionizing radiation (like UV) can cause dimer formation between bases #

DNA Repair

Thymine dimer reparation has many mechanisms due to many organisms being exposed to UV

Proofreading

Nucleotide excision repair

Direct repair

Mismatch Repair

Ames test: used to check for mutation rate that happens with exposure to a compound

Types

Point mutation

Missense mutation

Nonsense mutation

Conditonal mutation

Silent mutation

Deletion or Insertion

frameshift mutation

(substitution of a single base)

(insertion or deletion of one or more bases)

Transversion

Translation