lecture 13- prokaryotes Flashcards
what are the traits that archae has in common with bacteria
lack of nuclear envelope
lack of membrane bound organelles
circular chromosome
what traits that archae has in common with eukaryotes
peptidoglycan in cell wall
histones used to unravel genes
what are traits that are specific to archae
ability to grow at temperatures above 100 celsius (extremophiles)
cell membranes have membrane lipids
what are characteristics of bacteria and archae (prokaryotes)
unicellular
no nucleus
one circular chromosome
most have cell wall
asexual reproduction
ribosome structure is different than eukaryotes
what is the size of prokaryotes
0.5 to 5.0 um
what is a chemotroph
organism that gets its energy from chemical bonds
organic compounds or inorganic substrates
what is a phototroph
organism that gets its energy from the sun
what is an autotroph
organism that gets its carbon from the air
what is a heterotroph
organism that gets its carbon from organic compounds (existing molecules that it breaks down)
what is an obligate aerobe
they need oxygen for cellular respiration
what is a facultative anaerobe
will use oxygen if present but can also grow without it (fermentation)
what is an obligate anaerobe
cant grow with oxygen
will die
how do prokaryotes reproduce
by binary fission
why dont prokaryotes take over the earth since they divide so fast
competition between themselves
lack of ressources
what are endospores
dormant cell/spore that can survive harsh conditions and will revive when the conditions get better
what are methanogens
release methane as byproduct of cellular respiration
anaerobic environments (bottom of lakes/swamps or intestine tracts)
what are extreme halophiles
archae that can live in extremely saline environments (dead sea)
salt dehydrates cells so not many organisms can survive these conditions
what are extreme thermophiles
grow in hot environments 45-104 celsius
(hot springs and deep sea vents)
what are archae’s cell wall made of
proteins, glycoprotein (sugar and protein) or carbohydrates
what are the arrangements of strepto, staphylo and spirilla colony shape
strepto: chains
staphylo: clumps
spirilla: spiral/squiggly
where is the circular dna of prokaryotes located
in the nucleoid region
what do plasmids contain
genes that are useful in special circumstances
how are plasmids transmitted
bacterial conjugation/sex
how does bacterial conjugation happen
happens when two bacterial cells are temporarily joined
via sex pilus
characteristics of plasmids
circular
self replicating
why dont antibiotics cause resistance
they create an environment where bacterias containing antibiotic resistant plasmids/genes have no competition by eliminating non-resistant bacteria
what are the ecological roles of bacteria on earth
decomposers (major role)
mutualistic symbionts
producers
pathogens
what are the benefits of symbionts in humans
produce essential vitamins (e. coli)
prevent pathogens from invading (produce chemicals that are toxic to other bacterias)
prevent infections (skin and mucous symbionts)
how do bacteria help plants
they “fix” nitrogen (into ammonium or nitrate ions) so that the plants can use it for growth (nitrogen gas is unusable)
bacteria benefits from the good environment and plant can grow
what are the specialized cells in cyanobacteria where nitrogen fixation happens called
heterocysts
what organisms produce antibiotics
fungi, bacteria
why do fungi and bacteria produce antibiotics
because they cant move so they compete with the organisms around them, they release antibiotics to kill the others to get all the ressources to themselves
