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Lecture 21

BIOL 1090 Lecture Notes - Lecture 21: Cardiolipin, Electrochemical Gradient, Energy


Department
Biology
Course Code
BIOL 1090
Professor
Andrew Bendall
Lecture
21

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The mitochondria is the same as it was in ancient times!
Extremely pleomorphic tho!! (varies in size and length)
Glucose --> CO2 + H2O + Energy (36 ATP/glucose molecule!)
Aerobic mitochondria-dependant respiration = the reverse of photosynthesis!!
What it's usually depicted as
BUT - can undergo rounds of fission and fusion! (constantly happening!)
Oval-shaped
The "folds" inside mitochondria
Cristae
The "space" inside mitochondria
High protein concentration!
Gel-like consistency
Mitochondrial ribosomes
Encodes proteins integrated in IMM, ribosomes, tRNA
Mitochondrial DNA (mtDNA)
Matrix
High lipid, low protein content
Contains many enzymes with diverse metabolic functions!
Large channel proteins
When open --> membrane = freely permeable!
Porins!
Outer Mitochondrial Membrane (OMM)
High protein, low lipid content (3:1)
Increase surface area
Contain machinery for aerobic respiration of ATP form
Characteristic of bacterial membranes
Rich in cardiolipin phospholipid (in heart)
Cristae = double layer folds
Inner Mitochondria Membrane (IMM)
Inner-membrane space = between OMM & IMM
Double-membraned!
Glycolysis = in cytoplasm (outside mitochondria)
1.
Pyruvic acid oxidation = entirely in matrix
2.
Tricarboxylic acid (TCA) cycle (aka Krebs Cycle) = mainly in matrix, ends in IMM
3.
Provides cells with energy (ATP) from glucose!
Coenzymes in matrix (NADH/FADH2) ---high energy electrons--> electron carriers in IMM
4 complexes (integral proteins) + 2 helper proteins (ubiquinone & cytochrome C)
Series of electron carriers = Electron Transport Chain
Energy transfer at each complex = used to pump H+ from matrix to intermembrane space
Electrons (now low energy) transfer to final acceptor (O2) = produces H2O!
Electron transport + proton pumping = electrochemical gradient! (positive internal space)
1.
Controlled movement of protons back across IMM
When protons pass through ATP synthase --> convert potential energy of gradient to ATP!
Protein movement down gradient powers ATP synthesis
2.
Oxidative phosphorylation = ATP synthesis in mitochondria
When mitochondria have lots of energy ==> need to undergo fission (break down) to sustain itself!!
So high-energy mitochondria will fuse with low-energy mitochondria!! (and create new
gradient, make more ATP!)
When mitochondria still have high energy, phosphorylation will cease!
Fission & Fusion
Many proteins = translated in cytosol
Contains removable N-terminus "pre-sequence"! (25~30 positively-charged amino acid
residues)
Chaperones detect protein to Import complex
TOM (Translocase of Outer Membrane)
Post-translational import into mitochondria!
Protein Import into Mitochondria
Major Function of Mitochondria
Structure
BIOL*1090-01
Lecture 21 - The Mitochondria
March 28, 2016
8:30 AM
BIOL 1090 Page 1
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