Cellular Respiration Flashcards

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1
Q

Substrate-level phosphorylation

A

Substrate (organic molecule) gives phosphate to ATP

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2
Q

3 steps of cellular respiration

A

Glycolysis
Citric acid cycle
Oxidative phosphorylation

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3
Q

Glycolysis

A

“Splitting of sugar”
Oxidation of 1 glucose molecule to 2 pyruvate molecules
Occurs in cytoplasm of cell
2 major phases: energy investment phase and energy payoff phase
Overall yield: 2 pyruvate, 2 ATP, 2 NADH

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4
Q

Cell’s energy

A

ATP (GTP)

Reduced electron carriers (NADH, FADH, NADPH)

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5
Q

Chemotrophy

A

Use of organic material for energy (source of electrons)

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6
Q

Fructose 1,6-bisphosphate

A

Non-reversible intermediate generated in glycolysis

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7
Q

Oxidation of glucose

A

6O2 + C6H12O6 -(burning)> 6CO2 + 6H2O

G=-686 kcal/mol

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8
Q

Fate of pyruvate

A

Depends on O2 availability and availability of electron transport chain

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9
Q

Obligate aerobes

A

Require O2 as electron receptor

Cannot ferment

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10
Q

Facultative aerobes

A

Can switch between anaerobic respiration and fermentation (use NO2, CO2, or SO4 as electron receptor)

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11
Q

Fermentation

A

Takes place in absence of oxygen
Use pyruvate as an electron receptor
Regenerates NAD+
Less ATP than respiration
Alcohol: glucose is transformed into ethanol (2 steps, one of which releases CO2)
Lactic acid fermentation: glucose is transformed into lactate (direct reduction)

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12
Q

Comparison of cellular respiration and fermentation

A

Both use glycolysis to oxidize glucose and other organic fuels to pyruvate
Different final electron receptor: O2 (cellular respiration), NAD+ (fermentation)
Cellular respiration produces more ATP

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13
Q

Conversion of pyruvate to acetyl-CoA

A

Occurs in mitochondria

Products of sugar and fats converted

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14
Q

Citric acid cycle

A

Takes place in mitochondrial matrix
Step 1: addition of acetyl CoA
Step 2: oxidation- CO2 lost
Step 3: regeneration of oxaloacetate
Step 1: Acetyl CoA + oxaloacetate -> citrate
Steps 2-8: Citrate -> oxaloacetate
Net result: 3 NADH, 1 GTP, 1 FADH2, -2 CO2

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15
Q

Biosynthetic intermediates

A

Glycolysis and the citric acid cycle supply them

Cell doesn’t use all of its glucose to make energy

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16
Q

Gluconeogenesis

A

Transformation of lactic acid into glucose

Used when glucose is unavailable

17
Q

Glycogen

A

Storage form of glucose

18
Q

Beta-oxidation of fatty acids

A

Hydrocarbons from fat -> acetyl CoA + reduced electron carriers
Occurs in mitochondria
Fat is the main storage form of energy

19
Q

Mitochondrial matrix

A

Highly concentrated mixture of hundreds of enzymes, including those required for the oxidation of pyruvate and fatty acids and for the citric acid cycle

20
Q

Inner mitochondrial membrane

A

Folded into cristae
Contains proteins that carry out oxidation reactions of electron transport chain and ATP synthase
Electrochemical gradient forms across

21
Q

Outer mitochondrial membrane

A

Contains porins- permeable

22
Q

Mitochondrial intermembrane space

A

Contains enzymes that use ATP passing out of matrix to phosphorylate other nucleotides
Protons from electron transport chain accumulate here

23
Q

Chemiosmotic hypothesis

A
Peter Mitchell (1970s)
Proton gradient that is generated by electron transport chain drives ATP synthesis
24
Q

Electron transport chain

A

NADH dehydrogenase complex -> ubiquinone -> cytochrome b-c1 complex -> cytochrome c -> cytochrome oxidase complex -> O2
Proton pumps: NADH dehydrogenase complex, cytochrome b-c1 complex, cytochrome oxidase complex
Mobile electron carriers: ubiquinone, cytochrome c

25
Q

Proton motive force

A

H+ gradient

Used to drive ATP synthesis, energy source for transport (mitochondria), bacterial flagellar movement

26
Q

ATP synthase

A

Uses proton gradient to synthesize ATP
Inorganic phosphate in matrix joins to ADP: energy comes from protons turning motor
2 parts: transmembrane H+ carrier (F0), F1 ATPase
Reversible: ATP can be broken down to make H+ gradient

27
Q

Total ATP yield

A

Cell: 30 ATP/ glucose
121: 30-36 ATP/ glucose