Mutation In Bacteria Dr.Gulve R.M

Mutation are Permanent, heritable DNA changes in bacterial DNA Types of Mutation Point mutation (base substitutions) Missense mutation Nonsense mutation (premature stop) Silent mutation Insertions/deletions Frameshift mutation Dramatic change in amino acids Run-ons, premature stops (nonsense mutation) .

Occurs in DNA replication (1 in 109 bp) Chemical mutagens The Creation of Mutation (mutagenesis) Spontaneous mutation Occurs in DNA replication (1 in 109 bp) Chemical mutagens Base pair changers (nitrous acid) Base analogues (e.g.. 5 bromouracil) Frameshift mutagens (aflatoxin, benzpyrene) Radiation X rays, gamma rays break DNA, bases UV light causes knots in DNA strand Mutations in the genetic instructions usually changes the resultant protein with deleterious effects

A heritable change in the genetic material called Mutation. Mutations may be neutral, beneficial, or harmful Mutagen are agent that causes mutations Spontaneous mutations are mutation occurs in the absence of a mutagenic agent

Base pair altering chemicals (base modifiers) deaminators like nitrous acid, nitrosoguanidine, or alkylating agents like cytoxan Base analogues “mimic” certain bases but pair with others - E.g. 5-fluorouracil, cytarabine

Ionizing radiation (X rays, gamma rays, UV light) causes the formation of ions that can react with nucleotides and the deoxyribose-phosphate backbone. Nucleotide excision repairs mutations

UV radiation causes thymine dimers, which block replication. Light-repair separates thymine dimers Sometimes the “repair job” introduces the wrong nucleotide, leading to a point mutation.