gen bio - lecture 9: cellular respiration

equation for cellular respiration

6 O₂ + C₆H₁₂O₆ = 6 CO₂ + 6 H₂O + energy (stored in ATP)

• exergonic (energy released)

define respiration

• changing the energy in the chemical bonds of food —> energy in ATP

  • occurs in all cells

  • aerobic or anaerobic

• CATABOLIC reaction (break down glucose for energy)

what are the two forms of energy involved

• NAD+ + 2 electrons + hydrogen = NADH (electron carrier)

• FAD + 2 electrons + 2 hydrogens = FADH2 (electron carrier)

  • NADH and FADH2 are stored energy used to make ATP

glycolysis (definition, input and products, where it occurs, phases, IN/OUT/CREATES for one glucose)

“sugar splitting” / breaking down glucose

• 1 glucose (6 carbons) —> 2 pyruvate (3 carbons each)

  • glucose enters by transport protein

• DOES NOT REQUIRE O2

• occurs in cytoplasm

• 2 phases: energy investment (USES ATP) and energy payoff (MAKES ATP)

IN: 2 ATP

OUT: 4 ATP, 2 NADH

CREATES: 2 pyruvate (3 carbons each)

glycolysis

• phase 1: energy investment

• endergonic process

• REQUIRES 2 ATP to break down glucose

  • results in 2 G3P (3 carbons each)

glycolysis

• phase 2: energy payoff

• EVERYTHING FROM HERE FORWARD = EXERGONIC

• generates 4 ATP + 2 NADH

  • results in 2 pyruvate (3 carbons each)

pyruvate oxidation (situation based on oxygen, catalyst, energy, IN/OUT/CREATES)

• if there is oxygen present… process moves to mitochondria in intermembrane space

  • if there is no oxygen… lactic acid fermentation

• catalyzed by pyruvate dehydrogenase

• no ATP used/produced

IN: n/a
OUT: 2 NADH, 2 CO2
CREATES: 2 acetyl CoA (2 carbons each)

citric acid cycle

• takes place in MITOCHONDRIA

• starts w/acetyl CoA + oxaloacetate (4 carbons)

  • completely oxidizes acetyl CoA to CO2

  • each glucose goes through 2 turns of the cycle

IN: n/a

OUT: 2 ATP, 6 NADH, 2 FADH2, 4 CO2

net gain of cellular respiration

ATP, NADH, FADH2, 6 CO2

oxidative phosphoryation (general summary + list 2 parts)

• energy stored in NADH and FADH2 is used to create a proton gradient

• proton diffusion across inner membrane (chemiosmosis) drives ATP synthesis

electron transport chain + chemiosmosis

oxidative phosphorylation

• step one: electron transport chain

• series of electron carriers in inner mitochondrial membrane

• energy and electrons from electron carriers (AND OXYGEN) are used to make an H+ gradient via active transport

  • intermembrane space [H+] > matrix [H=]

  • without oxygen. O2 would be backed up and there would be no formation of a gradient = NO ATP SYNTHESIS

• point of ETC: minimize energy lost as heat and maximize energy saved at H+ gradient

oxidative phosphorylation

• step two : chemiosmosis

• energy coupling mechanisms used to synthesize ATP

• converts potential energy in H+ gradient to potential energy in ATP

  • ATP made by ATP synthase

oxidative phosphorylation

• step two : chemiosmosis

  • focus on ATP synthase

• protein complex

• inner mitochondrial membrane

• the movement of H+ powers the enzymes in the catalytic knob of ATP synthase to phosphoralyze ADP —> ATP

  • H+ diffuses through (exergonic)

  • causes rotation