cellular respiration: a catabolic process that breaks apart glucose and strips it of its electrons
process of cellular respiration
equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP
GOAL: take one glucose molecule and make 38 molecules of ATP (dismantle)
3 steps:
glycolysis
- no oxygen needed
- occurs in cytoplasm
- glucose broken down into 3-carbon molecules called pyruvate
- produces 2 ATP, 2 NADH
link
- if oxygen is present, pyruvic acid broken down further into 2 acetyl COA (+2 NADH, releases CO2)
krebs [citric acid] cycle
- acetyl coa broken down
- CO2 released
- +2 ATP, 6 NADH, 2 FADH2
- occurs in mitochondria
- most of remaining energy is hydrogen attached to NADH + FADH2
electron transport chain
- occurs in inner membrane of the mitochondria
- electrons from NAD(H) passed to carrier molecules embedded in inner membrane; allows H+ protons to diffuse from matrix → inner membrane space
- forms steep proton gradient - H+ protons diffuse back down the gradient through ATP synthase; ATP is made as ADP picks up its third phosphate
- hydrogen electrons land on oxygen - final electron acceptor, makes water
- each hydrogen from NADH can make 3 ATP, each hydrogen from FADH2 makes 2 ATP
- 10 moles of NADH = 30 ATP
- 2 moles of FADH2 = 4 ATP
- glycolysis/krebs cycle = 4 ATP \n → total: 38 ATP \n