lecture two: prokaryotes Flashcards
prokaryotes were found
4 billion years ago
domiant prokaryotes are found in
- sea vents
- hot springs
- under ice
- desert
- europa ( moon)
cellular orginization of prokaryotes
- smaller than eukaryotes- about 1-10 micrometers
- simpler than eukaryotes
- lack membrane bound organelles
- one big compartment
- no nucleus, has nucleiod region
- plasma membran is folded inward, contains enzymes for respiration & photosynthesis
functions for cell well
- protects cell
- maintains shape
- prevents bursting
peptidoglycan
- carb polymer
- charecterisitc of domain bacteria only
can identify based on cell wall - not found in archea
two types of bacertial cell walls
- based on gram stain
- crystal violet -> purple
- safranin - pink
gram positive bacteria
- thick wall, primarly peptidoglycan
- remains crystal violet
- doesnt see safranin
- stains purple
- penicillin interferes w peptidoglycan sysnthesis
gram negative bacteria
thin peptidoglycan inner layer, lipoplysacchride outer layer
- does not remain crystal violet
- safranin visible
- stains pink
- gram - more oftern likely to cause serious diease
- lipo can cause fever
- important to differentiate to treat infections correctly
taxis
- directed movement in respoce to stimulis
- 50% of prokarotes are capapble of stimulus
what is the flagella
most common motility structure in prokaryotes
convergent evolution - analogous strucutre in different domains
flagella is found in
bacteria archea, eukaryotes
functions of flagllum
- H+ pumps across plastid membrane by ETC
- forms gradient H+ diffuse through motor
- E from diffusion turns motor
- proton motive force ( respiration
requirement for evolution
- sexual reproduction - recombination - genetic diversity
example of rapid reproduction and mutation
- E.coli in human intestine
significance of rapid mutations
- mutations rare on per gene basis
- short generations & large populations - increase genetic variation
- high diversity - rapid evolution - better adapted
epic experiment
- rapid mutations
- 12 e.coli populations, glucose runs out
- relative fitness in increased, having more mutations is more beneficial in the context
genetic recombination
combining DNA from 2 sources
transformation genetic recombination
prokaryotic cells take up foreign DNA from environment ( Griffiths experiment)
transduction genetic recombination
phages transfer prokaryotic genes from one cell to another ( virus mediated)
conjunction genetic recombination
- direct transfer of genetic materials from one cell to another, usually same species
- involved fertility factor 9F) - often a plasmid
F+ cell = cell that has F cell ( donor cell) - required for production of pili “ appendage for DNA transfer
- can transfer part of chromosome as well
genetic diversity
- prokaryotes are asexual
- reproduce rapidly
- have mechanisms for recombination - high genetic diversity
metabolic diversity needs
energy and carbon
metabolic energy sources
- phototrophs: E from light ( plants, green algae)
- chemotrophs: E from chemicals (humans)
metabolic carbon sources
- autotrophs: only need CO2, or other inorganic C ( can do carbon fixation)
- heterotrophs: required organic C , eg. glucose
key process of prokaryotic diversity
horizontal gene transfer
groups of bacterial diversity
- chlamydia
- spirochetes
- cyanobacteria
- gram positive b
probacteria
- large & diverse- 5 groups ( alpha,beta, gamma, delta & epsilsion
extremophiles live in
extreme environments
halophiles
high saline environments
thermophile/ hyperthermophiles
hot environemts
