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Flashcards in Cellular Respiration Deck (31):

-delta G per mole glucose




high energy H atoms removed from organic molecules


aerobic respiration overview

1. glycolysis
2. pyruvate decarbooxylation
3. Kreb/CAC/Tricarboxylic acid cycle
4. ETC = oxidative phosporylation

final products = O2 + H2O


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


substrate level phosphorylation

direct enzymatic transfer of transfer of P to ADP; no extraneous carriers needed


role of hexokinase

in glycolysis, it puts a P onto glucose so that it cannot diffuse out - tricks gradient


role of PFK

once hexokinase adds one P to glucose, it adds a second to make fructose-1,6-bisphosphate IRREVERSIBLE! committed to glycolysis


pyruvate decarboxylation

-pyruvate --> acetyl CoA + NADH + CO2
-net is 2 of each of those bc 2 pyruvate per glucose
-PDC = catalyst (pyruvate dehydrogenase complex)



pyruvate dehydrogenase complex, catalysts of pyruvate decarboxylation which converts pyruvate --> acetyl CoA + NADH + CO2


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



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



folds in the inner membrane of the mitochondria to increase SA for ETC oxidative phosphorylation


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



Coenzyme Q - ubiquinone; soluble carrier dissolved in membrane, can be fully oxidized/reduced



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


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



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.


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


what does Krebs produce and what happens to them

NADH/FADH2 - they are oxidized (lose electrons)


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


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


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+


facultative anaerobes

tolerate O2, but usually don't use it


obligate anaerobes

cannot be in presence of O2


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)


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


PFK = phosphofructokinase

catalyzes commitment step of glycolysis, fructose-6-phosphate to fructose-1,6-bisphosphate


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.


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


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.


protein as alternative energy source

least desirable
most aa are deaminated in liver, converted to pyruvate or acetyl CoA or other CAC intermediate and then enter respiration
oxidative deamination removes ammonia molecule directly from aa (ammonia = toxic to vertebrates - fish excrete it, birds/insects - uric acid, mammals - urea)