prokaryotes Flashcards
tree of life
bacteria, archaea, then eucarya branched off of archaea
prokaryotes lack membrane bound nucleus and organelles but have a
cell wall
cell wall contains
peptidoglycan
function of cell wall
maintains shape, provides protection, prevents osmotic bursting
2 types of cell walls
gram negative: thin peptidoglycan, lipopolysaccharide (endotoxin) and bilayered membrane, red
gram positive: thick peptidoglycan, single cell (plasma) membrane, purple
cell membrane/ plasma membrane
infolds for respiration/ photosynthesis
cell membrane function
selectively permeable; regulates movement in/out of cell
synthesis of cell wall components
assists w DNA replication
secretes proteins
contains flagella
what is cell membrane composed of
phospholipid bilayer, carbohydrates and proteins
capsule
coating of molecules external to the cell wall, made of sugars and/or proteins
capsule function
adhesion to substrate, cohesion, biofilms, protection against host immune system, camouflage from WBCs
centre of cell membrane is ____ and outer is ____
hydrophobic, hydrophilic
pili and fimbriae
when they are short an abundant the function is adhesion
when they are long and sparse the function is conjugation (joins one bacterium to another)
flagellum
allow bacteria to move, can rotate clockwise or anticlockwise, can be outside or inside the cell and when cell flexes moves in corkscrew motion
nucleoid
bacterial chromosome, single ring of DNA (haploid)
what exists in the cytoplasm
Ribosomal DNA
DNA on plasmids
-small circles of DNA, not essential for survival but advantageous in stressful conditions
bacillus shape
rods
coccus shape
balls
coccobacillus shape
ovals, somewhere inbetween coccus and bacillus
spriochaete shape
squiggles
endospores
large gram positive rods, thermostable and destroyed only by moist heat at 121 degrees for 15 mins, basis of sterilization standards
why is mycoplasma an unusual bacteria
-lacks cell well
-smallest autonomous growing organism
-simple
-pleomorphic: resistant to lysis
-found on mucosal surfaces
why is chlamydia an unusual bacteria
-energy parasite, stripped down genome, hijacks host metabolism
rickettsia
bacteria, obligate intracellular parasites (requires a host to fulfil life cycle)
usually vector borne
biofilms
mixed communities, embedded in a matrix, metabolic cooperation, resistance to removal
ways biofilms communicate
homoserine lactones (quorum sensing)
electrical signals
genetic exchange
two types of autotrophs
photoautotroph and chemoautotroph
two types of heterotophs
photoheterotroph and chemoheterotroph
photoautotroph energy source and carbon source
energy source: light
carbon source: CO2
chemoautotroph energy source and carbon source
inorganic chemicals, CO2
photoheterotroph energy source and carbon source
light, organic compounds
chemoheyerotroph energy source and carbon source
organic compounds, organic compounds
obligate aerobes
require O2 for respiration, growth
facultative anaerobes
-can survive with or without oxygen, prefer O2 but can ferment organic molecules for ATP
obligate anaerobes
poisoned by oxygen, use inorganic molecules or fermentation (organic molecules)
aerotolerant anaerobes
grow anaerobically, but don’t die in presence of O2
whats average generation time for prokaryotes (doubling time)
20 mins
conjugation
plasmid gene transfer
how do bacteria reproduce
asexual binary fission
one cell splits into two daughter cells
what are some ways genetic variation occurs in bacteria
mutation, transformation, conjugation and transduction
transformation
take up foreign DNA from environment
transduction
gene transfer between cells by viruses (phages)
extremophiles:
thermophiles; high temp
psychrophile; low temp
acidophile; acid
barophile; pressure
xerophile; dry
halophile; salt
name some human applications
microbial leaching/ mining, fuel production, bioremediation, biotechnology
first cellular life
cyanobacteria
utilized atmospheric elements to produce O2 which allowed for greater diversity of life
compare prokaryote cell wall to fungi’s and plant cell’s
prokaryote cell wall; peptidoglycan, gram pos or neg
fungi cell wall; chitin
plant cell wall; cellulose
general cell structure from out to in
surface filaments (pili and fimbriae, flagellum)
capsule
cell wall
plasma membrane
genetic material in cytoplasm (nucleoid; bacterial chromosome single ring of DNA (haploid), ribsomal DNA in cytoplasm, DNA on plasmids (not essential for survival))