microbial metabolism Flashcards
what three things do all organisms require
a source of carbon, electrons, and energy
what are the two types of carbon sources
organic molecules + CO2
what are the two types of energy sources
light + organic chemicals
what are the two types of electron sources
inorganic + organic donors
what two processes do chemoorganotrophs use to get energy from glucose
cellular respiration + fermentation
how do chemoorganotrophs obtain energy and electrons
through the oxidation of organic compounds
is oxidation exergonic or endergonic
exergonic (energy released)
what happens to the energy released from oxidation
it becomes trapped by ATP, then ATP carries the stored energy to sites where it’s needed
what does the cell require energy for
biosynthesis of materials, cell movement, material movement
what are the three major steps of aerobic respiration
glycolysis, CAC, ETC
what are the end products of glycolysis
2 pyruvate, 2ATP. 2NADH for every glucose
what organisms do glycolysis
all major groups of microbes, plants, and animals
what are the products of the CAC
for each acetyl-CoA, we get 2 CO2, 3NADH, 1 FADH2, 1 ATP/GTP
where do the electron carriers go after the CAC
to the ETC
how many ATP are produced by the ETC
32
which step of aerobic respiration produces the most ATP
ETC
where does glycolysis occur in eukaryotes
cytoplasm
where does CAC occur in eukaryotes
mitochondria matrix
where is the ETC in eukaryotes
inner mitochondrial membrane
T or F: aerobic respiration occurs in some prokaryotes
true
which prokaryotes utilize aerobic resp.
bacteria and archaea
where does glycolysis occur in prokaryotes
cytoplasm
where does CAC occur in prokaryotes
cytoplasm
where does ETC occur in prokaryotes
plasma membrane
what are the 3 different glycolysis pathways in prokaryotes
embden-meyerhof pathway
entner-doudoroff pathway
pentose-phosphate pathway
which organisms use the embden-meyerhof pathway
all major groups of microbes, plants, and animals
describe the oxygen conditions of the EMP
can function with or without O2
what does the EMP provide for the cell
precursor metabolites, NADH, and ATP
describe the two general phases of the EMP
6C phase: two ATP used, produces fructose1,6-BP
3C phase: pyruvate + other products are made
what is the yield of the EMP
2 ATP, 2 NADH, 2H+, 2 pyruvate
what organisms use the entner-doudoroff pathway
some gram-negative bacteria (especially those found in soil) + very few gram positive bacteria
T or F: eukaryotes can use the EDP
false
describe how the EDP differs from the EMP
at the end of the 6C phase we get one pyruvate and one G3p, and then that G3P will undergo the rest of the steps as we saw in EMP
what is the yield of the EDP
for one molecule of glucose: 1 ATP, 1 NADH, 1 NADPH, 2 pyruvate
which glycolysis pathway, EMP or EDP, makes more ATP
EMP, as it makes 2 ATP while EDP makes 1
which organisms use the pentose phosphate pathway
all types of organisms: eukaryotes and bacteria, but not archaea
describe the oxygen conditions required for the PPP
can function with or without O2
T or F: the PPP can operate at the same time as EMP and EDP
true
why is the PPP an important pathway
it produces NADPH which can be used in anabolic reactions
describe the general steps of the PPP
G6P (intermediate of EMP) is oxidized and NADPH is produced. 6-phosphogluconate is oxidized and decarboxylated = CO2 and more NADPH. Then sugar transformation reactions occur, producing G6P again and some pyruvate
what is the yield of the PPP
6 CO2, 12 NADPH, 12 H+, and P
how many protein complexes are in the ETC of eukaryotes
4
how many protein complexes are in the ETC of prokaryotes
3
other then NADH, where can bacteria get electrons (for the ETC step of cell resp.)
methanol
T or F: the ETC in prokaryotes is always linear
false; it can be branched (ie in E coli)
for branched ETC pathways in prokaryotes, what does the direction of flow depend upon
the amount of oxygen present
T or F: the ETC in prokaryotes may be shorter than the ETC in eukaryotes
true
which ETC produces more ATP: prokaryotic or eukaryotic
prokaryotic ETC produces less ATP
what is the terminal electron acceptor for aerobic resp.
oxygen
what is the terminal electron acceptor for anaerobic resp.
an exogenous TEA (nitrate, nitrite, sulfate, CO2, Fe3+)
define obligate anaerobes
bacteria that carry out anaerobic resp. only
give an example of obligate anaerobes
methanogens: they use CO2 as their TEA, they’re archaeons, and methane is produced
T or F: anaerobic resp. yields less ATP than aerobic resp.
true
T or F: some bacteria can carry out both aerobic and anaerobic resp.
true; depends on oxygen availability
what is fermentation
a process which glucose (or other substrate) is partially oxidized in the absence of oxygen
in fermentation, do all the steps of cell resp. still occur?
glycolysis is still performed, but no CAC or ETC
which step(s) of cell resp still occur in fermentation
only glycolysis
what is the terminal electron acceptor in fermentation
an organic molecule (usually pyruvate or a derivative of pyruvate)
what are two types of fermentation
lactic acid fermentation, alcoholic fermentation
describe lactic acid fermentation
NADH from glycolysis gives electrons to pyruvate, pyruvate is reduced into lactate
describe alcoholic fermentation
CO2 leaves pyruvate = acetaldehyde, NADH donates electrons = ethanol
T or F: some bacteria can utilize multiple fermentation pathways
true
what are the energy and electron sources of chemolithotrophs
they oxidize inorganic compounds
what do chemolithotrophs do with the electrons that they obtain from oxidation of inorganic compounds
they donate the electrons to the ETC
define nitrifying bacteria
a group of bacteria that use inorganic chemicals as an energy source
what is the most abundant photosynthetic organism on earth
cyanobacteria
where are photosystems and pigments located within a cell
on internal membranes
list the three types of phototrophy
oxygenic photosynthesis
anoxygenic photosynthesis
rhodopsin-based phototrophy
describe oxygenic photosynthesis
light energy is trapped with chlorophyll and accessory pigments to make ATP and NADPH, which then are used to fix CO2
what type of energy is used in oxygenic photosynthesis
light energy
what is made in oxygenic photosynthesis
ATP and NADPH are used to fix CO2
what types of bacteria use anoxygenic photosynthesis
almost all are strict anaerobes
T or F: anoxygenic photosynthesis uses chlorophylls
false; uses bacteriochlorophylls
what does anoxygenic photosynthesis use instead of chlorophylls
bacteriochlorophylls
where are pigments located in anoxygenic photosynthesis
in chlorosomes (which are found in an invagination of the PM)
what is the function of chlorosomes
pigments for anoxygenic photosynthesis are located in chlorosomes
T or F: rhodopsin-based phototrophy has no chlorophyll/bacteriochlorophyll involved
true
what does rhodopsin-based phototrophy use instead of chlorophyll
microbial rhodopsin (a protein)
describe rhodopsin-based phototrophy
acts as a light-driven protein pump that can produce a pH gradient to be used to make ATP
is there an ETC involved in rhodopsin-based phototrophy
no
