Mitochondrion and Chloroplasts (A Mitochondrion (Inner membrane = more…
Mitochondrion and Chloroplasts
Photosynthesis is a
reaction transferring an electron from water to carbon dioxide
Photosynthesis uses low energy electrons to form ATP and NADPH, which are then used to reduce carbon dioxide to carbohydrate.
Respiration removes high energy electrons from reduced organic substrates to from ATP and NADH
Oxidizes water to oxygen; Respiration reduced oxygen to form water
Evolved by endosymbiosis
Site of carbon dioxide fixation is the stroma
Self replicating organelles with their own DNA
Inner membrane: folded into flattened sacs (thylakoids), arranged in stacks called grana
Photosynthesis converts energy from sunlight into chemical energy stored in carbohydrates using the chloroplasts.
Takes place in chloroplasts.
Have a double membrane
Inner membrane contains light- absorbing pigment, electron carriers, and ATP - synthesising enzymes
Outer membrane contains porins and is permeable to large molecules.
Low energy electrons are removed from a donor molecule
By- products of oxygen metabolism (radicals) cause damage to molecules in the mitochondria
Endosymbiotic Origin of Mitochondria
Early prokaryotic cell (that could use oxygen) was engulfed by a primitive cell.
related closely to unicellular eukaryotes, lack an electron transport chain. They synthesise ATP from pyruvate breakdown via simple fermentation. (Roughly 4 mol of ATP per mole of glucose)
Hibernating animals have specialised mitchondria in their brown fat: these have a specialised channel protein that allows protons to return through the membrane and not make ATP.
The energy associated with this is lost as heat
Involved in programmed cell death
Amino acid and protein metabolism
Regulation of the cellular redox state
Metabolism of fatty acids
Make ATP from the krebs cycle and the electron transport chain, using oxygen as the final electron acceptor.
ATP Can be formed by glycolysis or oxidative phosphorylation in mitochondria
Accounts for 160kg of ATP in our bodies per day, the body contains approx 250g of ATP
Roughly 32 molecules of ATP per molecule of glucose
To make functional mitochondria we use proteins coded by the nucleus and by the DNA of the mitochondrion. The mitochondria DNA codes for 13 protein subunits and ribosomal and transfer RNA in mammals
RNA and proteins can be synthesised in the matrix of the mitchondrion
Contains Circular DNA, Ribosomes and enzymes
Inner membrane proteins with five types of functions
Mitochondria Fusion and Fission protein
Protein import machinery
Specific transport proteins that regulate metabolite passage into and out of the matrix
ATP synthase, which generate ATP in the matrix
Those that preform redox reactions of oxidative phosphorylation
Evolved by endosymbiosis
Inner membrane = more than 75%
Impermeable to even small molecules
Contains cardiolipin but not cholesterol: Cardiolipin can stop protons crossing the membrane
Outer membrane = 50% protein
Permeable to large molecules - even some proteins
Contains large pore-forming proteins called Porin
Is a membrane enclosed organelle found in most eukaryotic cells, Mitochondia is described as cellular power plants because they generate most of the ATP.
Singular = Mitochondrion
Plural = Mitochondria