Lecture 15: Mechanisms of Microbial Evolution Flashcards
homologous
related sequence that implies common ancestry
gene famlies
groups of gene homologs
paralogs
genes in an organism that is the result of gene duplication
orthologs
similar genes that differ because of speciation
evolution
change in allele frequencies in a population over time
mutations
random changes in DNA sequences
recombination
breaks & rejoins DNA segments to make new genetic combinations
nonhomologous / homologous
non- does not require similarity
homologous- requires similarity
fitness
ability of an organism to produce progeny & contribute to genetic material for future generations
deleterious mutations
increase fitness & removed by natural selection
beneficial mutations
increase fitness & are favoured by natural selection
a marker that colours cells red or white enables…
fitness measurement of evolved strains
horizontal gene transfer
transfer of genetic information between cells
what 3 mechanisms are used to transfer genes in prokaryotes?
- transformation
- transduction
- conjugation
where are metabolites found?
host cytoplasm
T or F: deletions removing biosynthetic genes might only have little effect on fitness
True
3 characteristics of horizontal gene transfer that differs from recombination
- unidirectional
- asymmetrical
- not constrained
gene conversion
replacement of recipient copy with donor copy
if there is no fitness benefit what happens to gene transfered from horizontal gene transfer
it is deleted over time
the mobilome
consists of all mobile genetic elements in a genome
insertion sequences
can generate chromosomal re-arrangements
how to detect horizontal gene flow
presence of DNA with GC content or codon bias that differs slightly
what do horizontally transferred genes do not encode
core metabolic functions
comparative genomics
uses whole genome sequencing technologies to analyze gene content
pan/core genome concept
genomes consist of 2 species
core genome
shared by all strains of the species
pan genome
includes all the optional extras present in some but not all strains of species
how are chromosomal islands acquired?
through horizontal gene transfer
chromosomal islands often belong to the ( ) genome
pan
