chapter 6 objectives Flashcards
micronutrients vs. macronutrients
macro: required in large quantities for metabolic processes
micro: required in smaller amounts (trace elements); present in enzyme function
autotroph
organism that use inorganic CO2 as carbon source
heterotroph
organism that must obtain carbon in organic form
chemotroph
microbe that gets energy from chemical compounds
6 essential nutrients of a bacterial cell
carbon, hydrogen, oxygen, nitrogen, phosphate, sulfur
diffusion vs osmosis
diffusion: molecules move in gradient from high concentration to low concentration
osmosis: water diffuses through selectively permeable membrane
effects of isotonic condition on cell
rates of diffustion are equal
effects of hypotonic condition on cell
water enters cell and in result it swells
effects of hypertonic condition on cell
water exits cell and in result shrinks
two types of passive transport
simple diffusion: no atp required, molecules move freely across membrane
facilitated diffusion: has binding site protein that moves molecules across membrane
one type of active transport
carrier mediated active transport: protein pumps that use ATP to carry molecules across membrane
endocytosis
ell encloses a substance in its membrane, forms a vacuole while engulfing a substance
phagocytosis
ingest an entire cell/solid matter
pinocytosis
ingestion of liquids like oils/molecules in a solution
6 enviornmental factors that effect cell growth
- temperature
- gases (oxygen/carbon dioxide)
- pH
- osmotic pressure
- radiation and atmospheric pressure
- other organisms
temperature group that contains most pathogens
mesophiles (growth at 25° C to 40° C)
5 groups of organisms based on oxygen requirements
aerobes: use oxygen in metabolism (obligate means cannot growth without)
microaerophiles: harmed by normal atmospheric concentrations of oxygen, but still require in small amounts
facultative anaerobes: do not require oxygen but use when present
obligate anaerobes: lack enzyme systems to use oxygen (cannot survive)
aerotolerant anaerobes: do not utilize oxygen but survive to a limited extent
capnophillic
organisms that grow best at higher CO2 tension than is normally present in the atmosphere
isotonic solution
concentration of solutes/pressures equal inside and outside cell
hypotonic solution
concentration of solutes/pressures is greater inside the cell than outside
hypertonic solution
concentration of solutes/pressures is greater outside the cell than inside
5 types of associations microbes can have with hosts
mutualism: both benefit
commensalism: one benefits, the other neither benefited nor harmed
parasitism: parasite benefits, host harmed
synergism: members cooperate/share nutrients
antagonism: some members are destroyed by others
steps of bacterial binary fission
B period: cell increases in mass and size
C period: dna replicates and the two strands separate
D period: synthesis of a septum forms two identical cells
doubling time
refers to specific time it takes for a bacterial population to double in time
how does doubling time lead to exponential growth
bacterial population is continuously doubling in size
4 phases of growth in bacterial growth curve
- lag phase: slow growth (adjusting to environment)
- exponential phase: rapid/exponential growth due to optimal conditions (acute infection)
- stationary phase: growth slows down because of depletion of nutrients (plataeu)
- death phase: decline in bacterial population (resolution)
6 ways we can measure cell growth
- optical density: measures cloudiness
- direct cell counting: counts individual cells
- colony-forming unit counting: plating diluted samples and counting colonies
- turbidity: measures light scattered by cells
- biomass: measuring total dry weight of the bacterial cells
- metabolic activity assays: measuring rate of specific metabolic processes
