chapter 24
stages of chemical and physical processes to produce simple cells
1) abiotic synthesis of small organic molecules such as amino acids and nitrogenous bases
2) the joining of small molecules into macro molecules
3) the packaging of these molecules into protocells
4) the origin of self replicating molecules
shapes of prokaryotic cells
rods spheres and spirals
prokaryotic cell wall function
prevents bursting in hypotonic solutions
contain peptidoglycan
gram stain
identifies levels of peptidoglycan in cells
gram positive contains more (appear darker)
gram negative contain less (appear pink)
phototrophs
obtain energy from light
chemotrophs
obtain energy from chemicals
autotrophs
require co2 as a carbon source
heterotrophs
require an organic nutrient to make organic compounds
photoautotrophy
energy from light
co2 carbon source
chemoautotrophy
energy from chemicals
co2 carbon source
photoautotrophy
energy from light
carbon from organic compounds
obligate aerobes
require o2 for cell respiration
obligate anarobes
are poisoned by o2 and use fermentation or anaerobic respiration
facultative anarobes
can survive with or without o2
first prokaryotes on earth were
obligate anarobes until photosynthesis formed
prokaryotes can reproduce by
binary fission
three factors that contribute to the considerable genetic variation in prokaryotes
1) rapid reproduction = binary fission
2) mutation = low rate but fast generations
3) genetic recombination
transformation
genetic recombination where foreign dna is taken from the environment
transduction
genetic recombination where movement of genes between bacteria by viruses
conjugation and plasmids
genetic recombination where sex pili allow cells to connect and pull together for DNA transfer
domain archaea
have some traits similar to bacteria and some with eukaryotes
more closely related to eukarya
extreme halophiles
archea
live in highly saline environments
extreme thermophiles
archaea
thrive in very hot environments
methanogens
archaea
live in swamps and marshes and produce methane as a waste product
anaerobes and are poisoned by o2
prokaryotes contribute to the biosphere through
chemical recycling
symbiosis
pathogenic bacteria
mutualism
both organisms benefit
commensalism
one benefits while other is unaffected
parasitism
parasite harms but doesnt kill its host
pathogenetic prokaryotes
cause disease by releasing exotoxins or endotoxins
exotoxins
cause disease even if the prokaryotes are not present
endotoxins
are released only when bacteria die and their cell walls break down