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Biology 1202B Lecture Notes - Oxidative Phosphorylation, Mitochondrial Matrix, Acetyl-Coa

Course Code
BIOL 1202B
Richard Gardiner

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Cellular Respiration
Cellular respiration – controlled mechanism of soring energy (rather than releasing
as heat/light)
Input of additional energy and a phosphate group “recharges” ADP to ATP
Cellular Respiration
A catabolic, exergonic, oxygen requiring process that uses energy extracted from
macromolecules (glucose) to produce energy (ATP) and water
oAutotrophs: harvest sunlight to covert radiant energy into chemical energy
Plants, some bacteria and some protists
oHeterotrophs: live off the energy produced by autotrophs (via
Fungi, animals, some bacteria and some protists
Cellular respiration is opposite of photosynthesis (C6H12O6 + 6O2 6CO2 + 6H2O +
Glucose Catabolism
Cells catabolize organism molecules/produce ATP in 2 ways:
1. Substrate-level phosphorylation – adding phosphate to a compound to
energize it
2. Aerobic Respiration
In most organisms both are combined (glycolysis, pyruvate oxidation, Krebs
cycle, ETC)
Breakdown of Cellular Respiration (four main reactions)
1. Glycolysis (splitting of sugar) – cytosol, just outside of membrane
2. Grooming Phase – migration from cytosol to matrix
3. Krebs Cycle (Citric Acid Cycle) – mitochondrial matrix
4. ETC and Oxidative Phosphorylation (or chemiosmosis) – inner mitochondrial
Ancient biochemical pathway that all organisms do (occurs in cytoplasm without
Priming reactions – begins with addition of energy (2 high-energy phosphates from
2 molecules of ATP are added to glucose (6C) producing a 6C molecule with 2
Cleavage reactions – 6C molecule with 2 phosphates is split, forming two 3C sugar
Energy Harvesting – each of the two 3C sugar phosphates is converted to pyruvate
in a series of reactions while an energy-rich hydrogen is harvested as NADH and 2
ATP are formed
Recycling NADH – as long as food is available to be converted to glucose, ATP can
be produced
oContinual production creates NADH accumulation and NAD+ depletion
NADH must be recycled to NAD+ through aerobic respiration (oxygen
as electron acceptor) or fermentation (organic molecule)
2 Phases (10 steps)
oEnergy investment phase – preparatory phase (first 5 steps)
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