Test Two Flashcards
when is a membrane potential generated
chemical or light energy is used to pump protons outside the cell
what type of process is diffusion
spontaneous
increase in entropy and negative free energy change
what is group translocation
a process that uses energy to chemically alter the substrate during its transport
function of membrane
separate what is outside the cell from what is inside
what do denitrifiers do
convert nitrate (NO3-) to N2
what is nitrification
ammonium to nitrate
what are organotrophs
use organic molecules as a source of electrons
what is denitrification
nitrate to N2
how does temp affect diffusion
increase temp moves molecules faster, faster they arrive at membrane
euglena are what type of trophic
mixotrophic
what are autotrophs
organisms that assimilate CO2 as a carbon source and reduce it to make complex cell constituents
what are chemoheterotrophs (organotrophs)
obtain energy from oxidation of chemicals and obtain C from organic compounds
what are chemoautotrophs
obtain energy from oxidizing inorganic molecules such as iron, sulfur or nitrogen. the energy is used to fix CO2 into biomass
what are two coupled transport systems
symport and antiport
how does surface area of the membrane affect diffusion
an increase in surface area results in an increased likelihood of molecules encountering the membrane
what is a glycerol transporter
more like a porin
glycerol or water binds and causes a conformational change, causing top to close and bottom to open to allow glycerol or water to pass through
what are siderophores
specialized molecules secreted to bind ferric ion (Fe3+) and transport it into the cell
what can nitrogen fixers do
possess enzyme, nitrogenase, which converts N2 to ammonium ions
where is phosphotransferase system is present in
all bacteria
is N2 stable
highly stable, requires energy to break bonds
what are heterotrophs
organisms that use of external sources of organic carbon compounds for biosynthesis
does active transport use energy
yes
what are chemoorganoheterotrophs
utilizing orgainc election sources
what is facilitated diffusion
a process of passive transport across the membrane facilitated by transport proteins
solutes move from high to low concentration
what is antiport
two different molecules transported in opposite directions
electroneutral
what is reduced nitrification
nitrate to ammonium
what are the two main types of ABC transporters
uptake ABC transporter
efflux ABC transporters
what forms an electrochemical potential
the hydrogen ion gradient plus the charge difference across the membrane
what is the structure of ABC transporters
2 hydrophobic protein that form membrane channel
2 peripheral cytoplasmic proteins that contain a conserved amino acid motif involved in ATP binding
what are chemolithoheterotrophs
utilizing inorganic electron sources
what are macronutrients
needed in large quantities
major elements in cell macromolecules
what is endocytosis
parts of the cell membrane bud into the cytoplasm and eventually separate from it to form endosomes
what are solute or substrate binding protein
in ABC transporter structure
extracytoplasmic protein that binds to substrate
“recruits”
how does concentration gradient of the dissolved solute affect diffusion
a larger gradient speeds up diffusion because the more molecules there are, the more will encounter the membrane and cross it
what are phototrophs
organisms that obtain energy from chemical reactions triggered by the absorption of light
how will thickness of the membrane affect diffusion
diffusion rates are inversely proportional to the square of the distance the solute must travel across the membrane
thinner means faster diffusion
what do nitirifiers do
oxidize ammonium (NH4+) to nitrate (NO3-)
based on niche, microbes have required additional what
growth factors
what are lithotrophs
use inorganic molecules as a source of electrons
in gram neg organism, where are solute or substrate binding proteins
float in the periplasmic space between the inner and outer membrane
all of earth’s life forms are based on…
carbon
hypotonic environment
net uptake of water by cell
cell swells and cell components are diluted
what is a membrane potential
energy stored by an electrical potential across a membrane
what are cofactors
small molecules that fit into specific enzymes and aid in catalysis
is coupled transport system active transport
yes
how does the mass of molecule affect diffusion
friction between molecule and its medium is a source of resistance that slows down motion
large molecules move slow across membrane
what are photoheterotrophs
obtain energy via light absorption and obtain carbon from organic compounds
how do siderophores reduce iron
enzymes reduce it to more soluble forms
what is diffusion
net movement from an area of high concentration to low concentration
what molecules are impermeable to membrane
large,uncharged polar molecules
ions
what are essential nutrients
compounds that a microbe cannot make itself but must gather from its environment
isotonic environment
equal concentrations of solute inside and outside of cell
water enters and exits cell at equal rates
where do nitrogen fixing bacteria live
free-living in soil or water, or they may for symbiotic associations with plants
how does the nitrogen cycle work
N2, nitrogen fixers, ammonium, nitrifiers, nitrate, denitrifiers then N2
what does ABC transporter stand for
ATP binding cassette
what is uptake ABC transporters used for
transporting nutrients
what are chemotrophs
obtain energy from oxidation-reduction reactions that transfer electrons from high energy compounds to make products of lower energy
what molecules are slightly permeable
small, uncharged polar molecules
algae are what type of trophs
photoautotrophs that produce biomass through photosynthesis
what is exocytosis
intracellular vesicles fuse with the cell membrane and the contents are released to the environment
what is mixotrophic
some organisms have than one type of metabolism
auto and heterotrophic
what are symbionts
an organism that lives in intimate association with a second organism
what is phagocytosis
cell eating; large extracellular particles are brought into cell
hypertonic environment
net loss of water from cell to environment , cell shrinks and cell components are concentrated
how does phosphotransferse system work
uses energy from phosphoenolpyruvate to attach a phosphate to a specific sugar
accommodates different substrates
what molecules are freely permeable
hydrophobic molecules
o2, co2, n2
what kind of transport does eukaryotes use
endocytosis, phagocytosis, pinocytosis, exocytosis
what are some macromolecules in microbes
carbohydrates, lipids, nucleic acids, and proteins in cells
ions for protein function such as mg2+, Fe2+, K+, Ca2+
where do siderophores release iron
released into the cytoplasm and reduced to ferrous form (Fe2+)
what is pinocytosis
cell drinkinig; endocytocis of small volumes of extracellular fluid
how does solubility of molecules in the membrane affect diffusion
hydrophobic molecules will dissolve in membrane
what are photoautotrophs
obtain energy via light absorption by the photolysis of H2), H2S etc. The energy used to fix CO2 into biomass
what are micronutrients
trace elements necessary for enzyme function
Co, Cu, Mn, Mo, Ni, Zn
what is electrochemical energy
energy stored in the form of an electrical potential existing between compartments separated by a membrane
when is active transport used
environments in which nutrient concentrations are low (aquatic systems)
environments where competition is high (soil systems)
what is owed towards the plasticity of microbial genomes
through evolution, bacteria have evolved ingenious strategies to find, acquire, and metabolize a wide assortment of food sources
where do you see siderophores
in all domains of life
what is osmosis
diffusion of water across selectively permeable membrane from regions of high water concentration to regions of low water concentration
what is chemical energy
energy stored in high energy phosphate bond in ATP
eukaryotic microbes are what kind of trophic consumer
heterotrophic
is phosphotransferase active transport
yes, still uses energy
what is efflux ABC transporters used for
multidrug efflux pump
pump anitbiotic out of cell, pump toxic out of cell
is Fe(OH)3 available for transport
no
electrochemical potential is also called
proton potential
proton motive force
what makes up 78% of earth’s atmosphere but is unavailable for use by most organisms
N2
Chemoheterotrophs are subdivided into
chemolithoheterotrophs
chemoorganoheterotrophs
in gram pos orgnanism, where are solute or substrate binding proteins
lack outer membrane, the proteins are tethered to the cell surface
what are coupled transport systems
those systems that harness free energy from moving an ion down its concentration gradient (from high to low) to drive the transport of another solute up or against its concentration gradient
what is an electrogenic process
unequal distribution of charge
what is axenic growth
growth outside of host cells
what is stored energy used for
to directly move nutrients in the cell via transport proteins
used to drive flagella motors
drive ATP synthesis
what are two forms of energy
chemical
electrochemical
how is selective permeability achieved
- substrate specific carrier proteins
- dedicated nutrient binding proteins that patrol the periplasmic space
- membrane spanning protein channels or pores
what type of iron is in most cells for nutrients
Fe(OH)3
what is the largest family of energy driven transport systems
ABC transporters
what is symport
two different molecules transported in same direction
electrogenic process
what is a defined mineral medium
medium that contains only those compounds needed for an organism to grow
