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Lecture 9

BIOL 1090 Lecture Notes - Lecture 9: Oxidative Phosphorylation, Phospholipid, Atp Synthase

Course Code
BIOL 1090
Andrew Bendall

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Biology 1090 Lecture 9
Usually depicted as oval, double membrane organelles, mitochondria undergo rounds of fusion and fission and
their shape can change to be considered tubular
Mitochondria undergo frequent fusion and fission
Have two membranes
1. Outer Mitochondrial Membrane (OMM)
High lipid, low protein
Contains many enzymes with diverse metabolic functions
Porins: large channel proteins that when open, membrane is freely
2. Inner Mitochondrial Membrane (IMM)
High protein : lipid ration (3:1)
Double-layered folds = cristae
o Cristae: increase membrane surface area and contain machinery
for aerobic respiration and ATP formation
Rich in a phospholipid called cardiolipin (characteristic of
bacterial membranes)
Aqueous Compartments of Mitochondria
1. Inter-membrane space
2. Matrix
o High [protein] gel-like consistency
o Mitochondrial ribosomes
o Mitochondrial DNA (mtDNA)
o Encodes polypeptides that are integrated into the
IMM ribosomes, tRNA
*nucleoid IMM associated but not membrane bound (mitochondrial DNA)
Major function of Mitochondrion
Provide cells with energy (ATP) obtained from glucose
o Glycolysis- occurs in the cytoplasm outside mitochondria
o Pyruvic acid oxidation- occurs entirely in mitochondrial matrix
o Tricarboxylic acid (TCA) cycle (aka Kreb Cycle)- Occurs mainly in matrix but ends in the IMM
Oxidation and breakdown of 1 molecule of Glucose = 36 ATP
Oxidative Phosphorylation: ATP Synthesis in the Mitochondria
Step 1: electron transport and proton pumping (generates an electrochemical gradient)
Step 2: proton movement down electrochemical gradient powers ATP synthesis
**When ATP formation is driven by energy released from electrons removed during substrate oxidation, the
process is called oxidative phosphorylation
Oxidative Phosphorylation: Step 1
High energy electrons pass from co-enzymes (NADH and FADH2) in matrix to electron carriers in IMM
Series of e- carriers (respiratory enzyme complexes I, II, III, IV) = Electron-Transport Chain
Energy transfer at each complex used to pump H+ from matrix into inter-membrane space
Eventually, low energy electron (e-) transferred to terminal e- acceptor (O2)
o H2O produced
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