Ch7 - Cellular respiration and fermentation Flashcards

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1
Q

Main purpose of cellular respiration

A
  • make ATP and NADH
  • mostly uses glucose but other organic molecules are also used
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2
Q

4 steps of glucose metabolism

A
  1. glycolysis
  2. breakdown of pyruvate
  3. citric acid cycle
  4. oxidative phosphorylation
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3
Q

Glycolysis

A
  • step 1 of cellular respiration
  • can occur with or without oxygen
  • happens in the cytosol
  • nearly identical in all living species
  • has ten steps that occur in three phases
    1. energy investment
    2. cleavage
    3. energy liberation
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4
Q

energy investment

A
  • first phase in glycolysis
  • steps 1-3
  • 2 ATP hydrolyzed to create fructose-1,6-biphsophate
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5
Q

cleavage

A
  • second phase of glycolysis
  • steps 4-5
  • 6 carbon molecules broken into two 3 carbon molecules of glyceraldehyde-3-phosphate
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6
Q

energy liberation

A
  • third phase of glycolysis
  • steps 6-10
  • two glyceraldehyde-3-phosphates broken into two pyruvate molecues
  • produces 2 NADH and 4 ATP
  • net ATP is 2 (cuz two invested in investment phase)
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7
Q

Warburg effect

A
  • cancer cells preferentially use glycolysis while decreasing oxidative phosphorylation
  • healthy cells generate most ATP from oxidative phosphorylation
  • this is because tumors aren’t usually vascularized, so they aren’t getting enough oxygen to do oxidative phosphorylation
  • used to diagnose cancers in PET scans
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8
Q

Breakdown of pyruvate

A
  • stage 2 in cellular respiration
  • pyruvate is transported to mitochondrial matrix (in Eukaryotes)
  • molecule of CO2 removed from each phosphate
  • remaining acetyl group attached to CoA to make acetyl CoA
  • yield: 1 NADH per pyruvate
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9
Q

how is pyruvate brought into the mitochondria

A
  • transported from cytosol to mitochondrial matrix via symporter
  • brings in H+ and pyruvate at the same time
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10
Q

pyruvate dehydrogenase

A
  • enzyme that breaks down (oxidizes) pyruvate once in the mitochondrial matrix
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11
Q

Citric Acid Cycle (Krebs cycle)

A
  • stage 3 of cellular respiration
  • breakdown of carbohydrates to CO2
  • acetyle is removed from Acetyl COA and attached to oxaloacetate
    • forms citrate (citric acid)
  • 8 steps release 2 CO2, 1 ATP, 3NADH, and 1 FADH2
  • oxaloacetate is regenerated
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12
Q

8 molecules in citric acid cycle (one for each step)

A
  1. citrate (6C)
  2. isocitrate (6C)
  3. ketoglutarate (5C)
    • Co2 is byproduct of formation
  4. succinyl-CoA (4C)
    • Co2 is byproduct of formation
  5. succinate (4C)
  6. Fumarate (4C)
  7. malate (4C)
  8. oxaloacetate (4C)
    can I keep selling stuff for money, officer?
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13
Q

Oxidative phosphorylation

A
  • stage 4 of cellular respiration
  • high energy electrons removed from NADH and FADH2 to make ATP via electron transport chain
  • Typically requires oxygen
  • phosphorylation occurs at ATP synthase to make ATP
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14
Q

Oxidation by electron transport chain (ETC)

A
  • involves proteins and small organic molecules embedded in the inner mitochondrial membrane
  • series of redox reactions accept and donate elections in a linear manner
  • each movement of electrons punts H+ against the electrochemical gradient
    • the buildup of electrons provides the energy to make ATP
  • FADH2 produces less usable energy because it skips a pump
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15
Q

chemiosmosis

A
  • chemical synthesis of ATP as a result of pushing H+ across a membrane
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16
Q

ATP synthase

A
  • protons can only pass through the inner mitochondrial membrane through ATP synthase
  • uses free energy from protons passing through to phosphorylize ADP into ATP
17
Q

maximal amount of ATP from NADH

A
  • yield = 30-34 ATP molecules per glucose
  • maximal amount is rarely achieved
    • NADH also used in anabolic pathways
    • H+ gradient used for other purposes
      ex: pyruvate gets into the mitochondria via symport with H+, so those hydrogens can’t be used to make ATP
18
Q

ATP synthase

A
  • converts energy from the proton motive force of the H+ gradient to chemical bond energy in ATP
  • as the H+ flows through, the green guy spins, bringing the ADP and inorg phosphate together
  • conformation changes produce ATP
  • be able to draw vaguely - the balloon part in the in matrix
19
Q

carbohydrate, protein, and fat metabolism

A
  • carbs, protein, and fat can be used for energy, not just glucose
  • use same pathways to increase efficiency, but enter glycolysis or citric acid cycle at different points
20
Q

anabolism

A
  • using metabolism to make molecules
21
Q

strategies for environments that lack oxygen

A
  1. use substance other than oxygen as the final electron acceptor in ETC
    • ex: E.coli uses nitrate
  2. produce ATP only via substrate level phosphorylation
22
Q

substrate level phosphorylation

A
  • method of synthesizing ATP that occurs when an enzyme directly transfers a phosphate from an organic molecule to ADP
  • phsosphorylated organic molecule and ADP bind to the enzyme and, therefore, are the enzyme’s substrates
    • ADP is then phsophorylated to form ATP
23
Q

Fermentation

A
  • the breakdown of organic molecules without net oxidation
  • in anaerobic conditions, organisms that use O2 as final electron acceptor need another way to produce ATP (like glycolysis)
  • Glycolysis makes too much NADH, which is bad (no longer have NAD+)
  • muscles solve this by reducing pyruvate into lactate
  • yeast solve this by making ethanol
  • fermentation makes a lot less ATP than oxidative phosphorylation