Chapter 11- Catabolism, Energy Release, and Conservation Flashcards
use light
phototrophs
obtain energy from oxidation of chemical compounds
chemotrophs
use reduced inorganic substances
lithotrophs
obtain electrons from organic coupounds
organotrophs
organic carbon, organic electron donor
chemoorganoheterotroph
organic carbon, inorganic electron donor
chemolithoheterotroph
What is the energy currency of reactions?
ATP
complete or incomplete oxidation of organic compound, release energy, use organic molecules as energy, 3 processes (aerobic cellular respiration, anaerobic cellular respiration, fermentation)
chemoorganotrophic metabolism
complete oxidation of organic molecule to 6 CO2, use ETC, proton motive force, synthesizes ATP by ATPsynthase
cellular respiration
final electron acceptor is always O2, catabolize and oxidize organic energy source for CO2, exergonic produces ATP and high energy electron carriers
aerobic cellular respiration
final electron acceptor is never O2, complete catabolism of the starting organic molecule to CO2, ETC but never final e acceptor of O2, less energy than aerobic
anaerobic cellular respiration
organic acceptors can be used, exogenous acceptor such as NO3, SO4 and CO2
oxidative phosphorylation
incomplete oxidation of organic molecule, end in organic acids or alcohol, endogenous electron acceptor, no ETC or proton motive force, ATP synthesized only by substrate level phosphorylation
fermentation
enzyme catalyzed reactions where product of one is substrate of next reaction, provide materials for biosynthesis, amphibolic pathway
catabolic pathway
catabolic and anabolic pathway, include Embden Meyerhof pathway, pentose phosphate pathway, and TCA cycle
amphibolic pathways
What are the 4 phases of aerobic cellular respiration?
(1) glycolysis
(2) formation of acetyl CoA
(3) Citric Acid/Krebs Cycle
(4) Electron Transport/Oxidative Phosphorylation
6 molecules of glucose to 2 molecules of pyruvate (3C each), net to 2 ATP & 2 NADH, performed in cytoplasm in prokaryotes and eukaryotes
glycolysis
removal of 1 carbon dioxide from pyruvate to form 2 carbon acetyl group, combine with conenzyme A, 2 NADH produced
formation of acetyl CoA
2 carbon acetyl group completely oxidized to CO2, 2 GTP produced and converted to ATP, 6 NADH and 2 FADH produced
Citric Acid/ Krebs Cycle
NADH and FADH released during electron transport, some of energy is used to drive ATPase for ATP synthesis during process
electron transport/oxidative phosphorylation
occurs in cytoplasm matrix of most eukaryotic microorganisms, plants, animals, and along inner cytoplasmic membrane in prokaryotes, most common degradation of glucose to pyruvate, function in presence or absence of O2, addition of 2 phosphates is activation energy, ATP synthesized by SLP
the embden meyerhof pathway (glycolysis)
what are the steps to the embden meyerhof pathway
glucose 6 —> fructose 1,6P —->aldolase —-> glyceraldehyde 3-P ——> glyceraldehyde 3-P dehydrogenase —> 1,3 bisphosphoglycerate
used by soil bacteria and few gram negative bacteria, replaces 1st phase of embden meyerhof pathway, yield 1 ATP/NADPH/NADH per glucose
enter dudoroff pathway
aka hexose monophosphate pathway, can operate at same time as glycolysis or EDP, aerobic or anaerobic, amphibolic, used by many microorganisms, starts with glucose 6p
pentose phosphate pathway
common in aerobic bacteria, free living protozoa and algae/fungi, produce carbon skeletons for biosynthesis and energy metabolism
tricarboxlyic acid cycle/citric acid cycle
in the TCA ___________ + __________ forms citrate
oxaloacetate and acetyl CoA
for each acetyl CoA oxidized, the TCA produces
2 molecules of CO2, 3 molecules of NADH, 1 FADH2, and 1 GTP
a series of electron carriers operating together to transfer electrons from NADH and FADH2 to terminal electron in O2, flow from more negative to positive reduction, each carrier reduced and reoxidized, difference in reduction potentials results in great release of energy
electron transport chain
located in cell membrane, some may resemble mitochondrial ETC, different ETCs and may be branched, shorter
bacterial and archaeal ETCs
ATP synthesized as the result of electron transport driven by the oxidation of a chemical source
oxidative phosphorylation
most common hypothesis for OP, protons move outward from mito matrix as electrons are transported down the chain, concentration gradient forms, PMF formed
chemiosmotic hypothesis
ATP yield in eukaryotes is about ________ and about ________ in prokaryotes
30 and 16-28
bacterial ETC are shorter and have lower P/O ratio, ATP production varys based on environmental condition, PMF in bacteria and archaea is used for other purposes than ATP production, precursor metabolite may be used for biosynthesis
factors affecting ATP yield
oxidized inorganic ______ compounds are the mos common acceptors
nitrogen
denitrifying bacteria in soil play role in denitrification, recyclers
reduction of nitrogen to nitrogen gas
inorganic compounds oxidized in sulfur compounds, prokaryotes in soil and water, play key role in sulfur cycle
sulfur reduction
use CO2 as final electron acceptor, reduce it to CH4 methane
methanogenesis
monosaccharides converted to to other sugars that enter glyolytic pathway, di and polysaccharides cleaved by hydrolases or phophorylases
carbohydrate catabolic activity
stored substances used as energy sources in absence of external nutrients, glycogen to starch by phosphorylases
reserve polylmers
fatty acids oxidized by beta oxidation pathway, glycerol degraded via glycolytic pathway, triglycerides hydrolyzed to glycerol and FA’s by lipases
lipid catabolism
hydrolyzes protein to amino acids
protease
removal of amino group from amino acid
deamination
What are the 3 major groups of chemlithotrophs?
(1) hydrogen oxidizing bacteria
(2) sulfur oxidizing microbes
(3) nitrifying bacteria
oxidize H2 to relase energy and electrons, seen in archaea and bacteria, deep Earth and Sea, catalyzed by hydrogenase (separates protons and electrons), often facultative,
hydrogen oxidizing bacteria
many reduced sulfur compounds are used as electron donors, H2S, S0 and S2O3 are most common end products, lower pH of surroundings, usually aerobic
sulfur oxidizing bacteria
compounds oxidized by nitrifying bacteria during nitrification, nitrosomonas (NH3>NO2) and nitrobacter (NH2>NO3)
nitrogen oxidation (nitrification)
calvin cycle requires NADPH as electron source for fixing CO2, use reverse electron flow to generate NADPH, electrons flow in opposite direction as ETC
reverse electron flow by chemolithotrophs
flexibility of chemolithotrophs
can be chemolithotrophic or chemoheterotrophic, can be autotrophic or heterotrophic
use energy from the sun and electrons from inorganic molecules, light energy converted to chemical bond energy in the organic molecules synthesized, CO2 is reduced to organic C6H12O6 (carbon fixation), brings carbon into ecosystem
photoautotrophic metabolism
anoxygenic photosynthesis uses ______
H2S
capture light energy, absorb some and reflect others, percieved color is reflected wavelength, produce some chlorophyll to be photosynthetic, chlorophyll is a porphyrin
photosynthetic pigments
in eukaryotes, chlorophyll is found in _________ but found in __________ in prokaryotes
thylakoids, cytoplasmic membrane or chlorosomes
transfer light to chlorophylls, cartoenoids and phycobiliproteins
accessory pigments
highly organized array of chlorophylls and accessory pigments, capture light energy and transfer in to a special reaction center
antenna pigments
antenna and its associated reaction center chlorophyll, 1 in anoxygenic and 2 in oxygenic, rxn centers participate directly in conversion of light to ATP
photosystems
light needed, ATP and NADPH made, anoxygenic electrons from H2S not H2O
light reactions
water split by photolysis, provide electrons for NADPH
oxygenic photosynthesis
both oxygenic and anoxygenic photosynthesis
ATP made by ATPase during electron transport (photophosphorylation)
phototropic green, purple, and heliobacteria, only 1 PS, reducing power for CO2 fixation comes from reductants of environment, H2O not electron source, O2 not produced
anoxygenic photosynthesis
light energy to generate chemical energy, NADPH from PS1, ATP from PS2, ATP can be produced by cyclic photophosphorylation, H2O in and O2 out
oxygenic photosynthesis
the reduction of CO2 to organic carbon, most common in calvin cycle
carbon fixation
