Flashcards in Cellular Respiration Deck (31):
1
-delta G per mole glucose
-686kcal/mol
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dehydrogenation
high energy H atoms removed from organic molecules
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aerobic respiration overview
1. glycolysis
2. pyruvate decarbooxylation
3. Kreb/CAC/Tricarboxylic acid cycle
4. ETC = oxidative phosporylation
final products = O2 + H2O
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glycolysis, products and overview
-decomposition of glucose into pyruvate in CYTOSOL
-NET: 2 ATP + 2 NADH + 2 pyruvate (+ 2 H2O + 2 H2)
-make 4 ATP, but put in 2, so net 2
-substrate level phosphorylation
-hexokinase adds P to glucose, PFK adds 2nd -- fructose-1,6-bisphosphate
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substrate level phosphorylation
direct enzymatic transfer of transfer of P to ADP; no extraneous carriers needed
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role of hexokinase
in glycolysis, it puts a P onto glucose so that it cannot diffuse out - tricks gradient
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role of PFK
once hexokinase adds one P to glucose, it adds a second to make fructose-1,6-bisphosphate IRREVERSIBLE! committed to glycolysis
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pyruvate decarboxylation
-MITOCHONDRIA
-pyruvate --> acetyl CoA + NADH + CO2
-net is 2 of each of those bc 2 pyruvate per glucose
-PDC = catalyst (pyruvate dehydrogenase complex)
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PDC
pyruvate dehydrogenase complex, catalysts of pyruvate decarboxylation which converts pyruvate --> acetyl CoA + NADH + CO2
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Krebs/CAC/TCA cycle
acetyl CoA merges with oxaloacetate --> citrate (7 intermediates)
each acetyl CoA produces 3 NADH + 1 FADH2 + 1 ATP (SUBSTRATE PHOS)
-animals exhale the CO2
-Mitochodrial Matrix
-NET = 6 NADH + 2 FADH2 + 2 ATP + 2CO2
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ETC
electron transport chain in inner membrane/cristae (folds to increase surface area)
-oxidative phosphorylation
-O2 = final e- acceptor, combines with native H+ to form H2O
-NADH and FADH2 = coenzymes, more H+ pumped across per NADH (3:2)
-ATP synthase uses pH/elec gradient to make ATP as it shuttles H+ back into the matrix
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cristae
folds in the inner membrane of the mitochondria to increase SA for ETC oxidative phosphorylation
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oxidative phosphorylation
ADP --> ATP from NADH + FADH2 via passing off electrons through various carrier proteins; energy does not accompany the P group but comes from the e- in ETC that establishes the H+ gradient which then supplies energy to ATP synthase
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CoQ
Coenzyme Q - ubiquinone; soluble carrier dissolved in membrane, can be fully oxidized/reduced
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CytC
cytochrome C: used for genetic relationships because common to many organisms; non protein parts (Fe) - donate/accept e-
transfers electrons between complexes III and IV
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total energy of aerobic respiration
1 glucose ~36ATP (38 in prok) but actual yield more like 32 based on mitochondrial efficiency
prokaryotes = no mitochondria to transport pyrute into so they dont lose 2 ATP to active transport because they use cell membrane for respiration
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chemiosmosis
he movement of ions across a selectively permeable membrane, down their electrochemical gradient. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration.
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ATP synthase
enzyme that makes ATP by chemiosmosis. It allows protons to pass through the membrane and uses the kinetic energy to phosphorylate ADP, making ATP
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what does Krebs produce and what happens to them
NADH/FADH2 - they are oxidized (lose electrons)
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anaerobic respiration, overview
-in cytosol
-glycolysis and fermentation
-why? w/o O2, NADH accumulates and no NAD+, so no glycolysis or ATP production
-fermentation = alcohol in plants, fungi, bacteria & lactic acid in human muscle cells, microorgs, etc
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alcohol fermentation
pyruvate --> acetylaldehyde + CO2
acetylaldehyde + NADH --> ethanol + NAD+
-acetylaldehyde = final e- acceptor (it is reduced) to form ethanol; analogous to O2 being final e- acceptor
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lactic acid fermentation
pyruvate + NADH --> lactate + NAD+
lactate goes to liver for conversion back to glucose once surplus ATP available
Lactate dehydrogenase catalyzes the interconversion of pyruvate and lactate with concomitant interconversion of NADH and NAD+
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facultative anaerobes
tolerate O2, but usually don't use it
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obligate anaerobes
cannot be in presence of O2
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priority of energy sources
1. glucose 2. other carbs 3. fats 4. proteins (2,3,4 - first converted to glucose or glucose inetrmediates and then degraded in gylcolysis or CAC)
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other carbs as energy source
hydrolyzed into monosaccharides, most of which can be converted to glucose or gluucose intermediates; glycogen is source - all cells capable of producing/storing it but muscle and liver haver large amounts
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PFK = phosphofructokinase
catalyzes commitment step of glycolysis, fructose-6-phosphate to fructose-1,6-bisphosphate
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insulin, glucagon
insulin - stores glucose as glycogen; glucagon - turns on glycogen --> glucose degredation
insulin activates PFK2 and glucagon inhibits it; when glucose is high, insulin -- glycolysis is stimulated and gluconeogenesis is inhibited.
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fats as alternative energy source
-carbons more reduced state, so more energy (9 kcal/mol vs 4 in carb adn pro)
-lipases in adipose tissue are sensitive to glucagon, which is active hormone when glucose levels low
-glycerol --> PGAL, enters glycolysis
-FA --> 1 acetyl CoA per every 2 C in FA chain
-costs 2 ATP to activate FA in cytoplasm, transport into mitochondria
-beta-oxidation: for every cut, 1 acetyl CoA-->krebs-->1 NADH + 1 FADH2
-unsaturated FA: 1 fewer FADH2 for each double bond
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beta oxidation
process by which fatty acid molecules are broken down in the mitochondria to generate acetyl-coA, which enters the citric acid cycle, and NADH and FADH2, which are used by the electron transport chain.
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