module 2: metabolism, genetics, and environmental microbiology Flashcards
are bacteria limited on how much they can replicate?
no, their only limit is their environment/resources
describe how bacteria grow as a species
they grow in size in their species (numbers). they do not grow as humans do in size
how do bacteria grow?
they double
describe the “surface area to volume ratio”
at a small size, the ratio is small and very efficient. cell exchanges with its world, gets gasses & nutrients, etc.
as the ratio gets bigger, the SA to V ratio gets worse and the diffusion isn’t as efficient
why cant you have huge bacteria?
there’s not enough surface area to volume exchange to efficiently get everything diffused out of/into the cell that it needs to survive
how do bacteria reproduce?
binary fission
describe the steps of binary fission
- DNA has to get replicated
- cell starts out with one circular chromosome
- a whole other circle chromosome has to get produced
- the two circles move to different ends of the cell
- SEPTUM pierces off in the middle
- pops apart into 2 separate cells
what is important about the septum?
the cell wall has to be re-established here
are bacteria clones?
yes. clones = exact replica
what doubles faster than any other bacteria?
E. coli
what is a closed growth system?
a flask or incubator. humans can also be considered a closed growth system.
describe the “standard closed system growth”
- lag phase (bacteria have a period of time where they get used to their environment)
- log phase (they grow rapidly… exponential growth)
- stationary phase (dying cells = replicating cells)
- death phase (more cells dying than are replicating)
describe mutations
when DNA is getting replicated, the cells will all be the same species but might have some small genetic differences as the population grows
describe what a “biofilm” is
a new hypothesis that some bacteria have the ability to live in a community. they are still single-celled, but live in a mass or clump
what is special about a biofilm? where are they commonly found?
they are very hard to kill. they are found in joint replacements (knee, hips, shoulder)… called a “biofilm infection”
how do biofilm infections grow?
they start as a little colony, then grow into a scaffold where they excrete protein so they can grow into a pod/film. the outside of the film take the brunt of the antibiotic
what are the 4 environmental factors of microbial growth?
oxygen, temperature, UV light, pH
describe oxygen in terms of microbial growth
oxygen is not required for all bacteria
what is aerobe
with oxygen
what is anaerobe
no oxygen
obligate aerobes…
do require oxygen
obligate anaerobes…
do NOT require oxygen. oxygen is harmful to them
facultative anaerobes…
flexible. can handle oxygen. some use it, but are fine without it as well
aerotolerant anaerobes…
don’t use/need oxygen, but are fine with it being around