BIOB10H3 Lecture Notes - Lecture 7: Atp Synthase, Isoleucine, Cytosol
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•Arose from phagocytosis of aerobic prokaryote
•Can divide in the cell
•“powerhouse of the cell”
–Site of aerobic respirations
•Site of aerobic respiration
–Utilizes oxygen to extract energy from macromolecules and converting it to
-Primarily from glucose: ATP production.
Mitochondria –ATP production
•We use 2 X 1026 molecules of ATP a day
-ATP: cells energy source: energy is released when ATP is hydrolyzed to ADP
•Amount of mitochondria in cells depends on energy needs
•many mitochondria in: muscle cells, liver cells, fat cells, plant cells & sperm
•Usually sausage-shaped but can be spherical (early embryos) or elongate,
-0.2 -2 um in cross-sectional diameter & 1-4 um in length (similar in size to
•Size and number of mitochondria reflect energy needs of the cell
–Change shape, move from place to place in cytoplasm
•Mitochondria can fuse with one another, or split in two.
–The balance between fusion and fission is likely a major determinant of
mitochondrial number, length, and degree of interconnection.
•Inner and outer mitochondrial membranes enclose two spaces
-The matrix and the Intermembrane space
•Outer mitochondrial membrane is outer boundary
•Inner mitochondrial membrane subdivided into 2 interconnected domains
Inner boundary membrane
Cristae: where the machinery for ATP is located
Phase-contrast light microscope can be picked up
Bright field stain:
To see inner membrane structure light microscope is not enough:
Outer Mitochondrial Membrane (OMM)
•~ 50% protein: very porous
•Porin proteins –large channels : Bacteria-like Beta pleated sheets.
•Allows very large molecules in
Inner Mitochondrial Membrane (IMM)
•~ 75% protein
•Unusual lipid composition
-No cholesterol, rich in cardiolipin: typical of bacterial plasma membranes
-like bacterial plasma membranes
–Requires channels and pumps
•Over 100 different proteins
–Electron transport chain (ETC)
-IMM forms cristae-many thin folds to increase the surface area
•Gel-like, from high protein concentration
•Contains circular DNA molecule(s), ribosomes and tRNA
•Mitochondrial DNA encodes for 37 genes
•However, mitochondrial function requires 3000 proteins
•Mitochondria proteins are completely translated on free ribosomes in cytosol
•Proteins must then be imported into the mitochondria
Posttranslational uptake of proteins into mitochondria
•IMM integral proteins: includes all the proteins of the ETC and the ATP synthase.
•Matrix proteins: includes all the enzymes of the Krebs / citric acid cycle.
How do mitochondria make ATP?
•Start with Glucose (or amino acids, or glycerol and fatty acids)
•Series of chemical reactions
-Performed by enzymes (proteins)
–Acts on substrates (targets) to produce a chemical change in the substrate