Lecture 9 Part 1 (Genetic mutation, horizontal gene transfer) Flashcards
What is a genetic mutation?
Any change in the nucleotide sequence of the genome
What are the 3 ways that genetic mutation may occur?
1) Switched base pairs from one to another
2) Loss of base pairs
3) Addition of base pairs
What is a wild-type organism?
the natural, non-mutated state
What is a mutant organism?
Bears some change in the nucleotide sequence
T/F: Mutant organisms always have a phenotypic change
F
What are the 3 causes of mutation?
1) Spontaneous
2) Induced (chemical or physical)
3) Horizontal gene transfer
What are spontaneous gene mutations?
Due to random errors during DNA replication
What are induced mutations?
Results from exposure to physical or chemical mutagens
What is a chemical mutagen?
1) a type of induced mutation
2) can insert between adjacent bases
3) Can “mimic” a base (nitrogenous base analogs)
What is a physical mutagen?
1) a type of induced mutagen
2) UV rays: cause abnormal bonds between adjacent nucleotides (often cause thymine dimers)
3) X-rays and gamma rays: introduce small breaks in DNA strands
What is horizontal gene transfer?
1) ex: DNA recombination
2) When genes are shared between microbes
T/F: All mutations are beneficial to the microbe
F (Most are not, but some mutations can contribute to success in individual microbes)
What are selective agents?
1) They kill susceptible microbes but leave resistant ones behind
2) Ex: antimicrobial drugs (penicillin resistance), disinfectants
What are protective mutations?
1) Mutations that aid in survival in the face of selective agents
2) Microbes rely on and keep protective mutations as long as the selective agent is present (ex: antibiotic resistance)
T/F: Antibiotic use “selects for” resistant microbes
T
