prokaryotes Flashcards
who discovered archaea?
Carl Woese
what was the third new domain that Woese discovered? and what kingdoms did it comprise.
monera, split into eubacteria and archaea
what is an endosymbiont?
an organism that lives in the body of another
what are the 2 classifications of bacteria?
gram-positive, gram-negative
what are 2 characteristics of gram-positive bacteria?
thicker walls/peptidoglycan layers, stain purple (positive)
what’s the first amino acid in all archaea and eukaryote proteins?
methionine
what’s the first amino acid in all bacteria proteins?
formylmethionine
what is the DNA organization of archaea?
circular with histones
what is the DNA organization of bacteria?
circular (w/o histones)
what is the DNA organization of eukaryotes?
circular with histones
bacteria that require oxygen are called
obligate aerobes
what are facultative aerobes?
bacteria that can perform aerobic respiration when oxygen is present, and perform anaerobic respiration/fermentation when it is not
what are obligate anaerobes?
bacteria that cannot live where oxygen is present
list the subgroups of the phylum euryarchaeota
methanogens, halophiles, thermophiles (lithotrophs), psychrophiles
what is a requirement for methanogens’ environment?
anoxic/low oxygen
where can methanogens be found?
wetlands, digestive tracts
how do methanogens generate energy?
methanogenesis
where can halophiles be found?
environments with high salt concentration
dead sea, salt-preserved foods
where do halophiles get most their energy from?
food + air, some can use light
where can thermophiles be found?
extreme environments
hot springs, hydrothermal vents on ocean floor
what is said to be oldest/least evolved branch of the archaea phylogenetic tree?
thermophilic archaea
what is the final electron acceptor for thermophiles (archaea?)
sulfur
lithotropic means
able to oxidize sulfur and create sulfuric acid as a form of energy
where can lithotrophs be found?
low pH, extremely acidic environments
where can psychrophiles be found?
cold environments
arctic oceans
how many chromosomes do bacteria have?
1
what are the 2 forms in which bacteria carry DNA?
1 nucleoid: single loop of DNA
multiple plasmids: smaller loops of DNA, are not essential for cellular functions
on the outside of bacteria is… (name structures)
small hairlike pili
1+ flagella
how do bacteria reproduce? (recap)
asexually, binary fission
bacterial DNA is… (3 properties)
naked (no histones), no proteins associated, a singular circular chromosome in nucleoid
archaeal DNA is…
sometimes “naked” and sometimes possess histones
what are the extra small pieces of DNA in bacteria called?
plasmids
what do plasmids carry?
a few, non-essential genes that often provide benefits to the cell
what are inclusions?
vesicles in bacteria
what can inclusions include?
air (buoyancy), food granules (glycogen, sulfur)
what are vesicles in bacteria called?
inclusions
usually which type of bacteria are pathogenic?
gram-negative
what is are pilli used for?
transferring genetic material (plasmids) through cells, sticking to surfaces
name 4 methods that bacteria use to move
change in buoyancy, bacterial gliding, flagella, twitching motility
how do bacteria use flagella to move?
it rotates and is driven at the base
what is the theory for how bacterial gliding is achieved?
bacteria ejects slime and moves pili to push itself around
how does twitching motility work?
special pili used as a hook, pulls bacteria along
how do cyanobacteria use changes in buoyancy to move?
their internal gas vesicles regulate buoyancy in water
what compound is present in gram-positive bacteria that causes the purple stain?
more peptidoglycan
name the 6 shapes of bacteria (circle, slightly stretched, bean, more stretched, wave, coil)
coccus, coccobacillus, vibrio, bacillus, spirillum, spirochete
what is the prefix for bacteria found in pairs?
diplo-
what is the prefix for bacteria found in clusters?
staphylo-
what is the prefix for bacteria found in chains?
strepto-
what word is used for groups of bacteria in 4s and 8s? (2)
4: tetrad, 8: sarcina
what are dormant cells called?
endospores
what type of cell can form dormant cells?
bacilli (rod-shaped)
how do bacilli breathe?
they’re facultative anaerobes
why do endospores form?
the bacteria detects an unfavorable environment
what separates DNA from the rest of the cell during endosporulation?
spore septum
what is the compound that stabilizes the proteins and DNA in the endospore?
calcium dipicolinate
what is the extra layer that is added to the cell wall called? (during endosporulation)
spore coat
what occurs in the final stage of endosporulation?
dehydration
what is the purpose of the proteins that saturate the endospore’s DNA?
carbon + energy source during regermination, protects DNA
list things that the cortex is resistant to (endospore)
temperature, UV light, most chemicals
why is the dehydration of the endospore important? (speculated)
to resist heat and radiation
what happens when the spore regerminates? (hint: enzymes)
DNA repair enzymes repair damaged DNA
how does an endospore get activated?
rupturing the spore coat
by heat or water
what shape are spirochetes?
helical
how does binary fission occur?
DNA replicated, cross wall divides cell into 2 identical bacterium
what is bacterial sexual reproduction also known as?
conjugation, horizontal gene transfer
what are the 2 involved bacteria in sexual reproduction called?
the donor and the recipient
how does bacterial sexual reproduction work?
donor produces a sex pilus that attaches to the recipient and transfers plasmids
why are prokaryotic populations highly adaptable to changing conditions?
short generation time, genetic variability/mutations
what are antibiotics?
substances that restrict the growth of another microorganism
how can antibiotics work?
destroy bacteria by inhibiting cell processes, prevent bacterial reproduction by inhibiting binary fission
list ways in which bacteria can resist an antibiotic
impermeability - modified cell wall protein, inactivation - reduce antibiotic’s ability to bind to ribosomes, pump out, modification
