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26 Cards in this Set
- Front
- Back
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what are the functions of the mitochondria?
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produce ATP via aerobic metabolism
sequester calcium, protecting cell from toxic levels role in cell death via necrosis and apotosis generate heat in brown fat cells |
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what is the morphology of a mitochondria?
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cytoplasmic organelle w/ double mbn
can change shape (sheprical to filamentous) can change from orthodox <-> condensed: -orthodox: low levels of ATP produced, large mtx, small intermbn space -condensed: high levels of ATP produced, small mtx, large intermbn space |
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how do mitochondria divide?
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by fission; separate from cell mitosis
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what is the outer mbn of the mit composed of?
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has pores composed of channel-forming protein called porin
highly permeable to <5kDa has enzymes to break down lipids |
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what is the inner mbn of the mit composed of?
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enriched in unusual lipid (cardiolipin)
highly IMpermeable to macromolecules/ions unless a transporter is present cristae increase SA, which increases ATP synth; form adhesion sites b/w inner and outer mbns 3 types of proteins: proteins for oxidative rxns of resp chain, ATP synthase, transport proteins |
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what is in the intermembrane space of the mit?
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enzymes that use ATP ot phosphorylate other nucleotides
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what is in the matrix of the mit?
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enzymes for oxidative metabolism
enzymes of TCA cycle DNA for mtDNA mit ribosomes mit RNAs calcium granules |
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how can you stain for mit?
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H&E, but nonspecific
acid haematein (LM), specialized histochemical localization of mit enzymes for both LM and EM (i.e. cytochrome oxidase, succinate dehydrog) |
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describe oxidative phosphorylation in mit.
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1. production of acetylCoA in mtx from pyruvate and fatty acids
2. oxidation of acetyl CoA in TCA -> NADH & FADH2 produced in mtx 3. ETC in inner mbn a. electron pairs from NADH & FADH2 enter ETC of proteins, finally transfer to O2 b. during e- transport, H+ moved from mtx to intermbn space, creating an electrochem proton gradient (pH increased in mtx) 4. synthesis of ATP from ADP + Pi by ATP synthase of inner mbn, using energy from protons flowing down gradient |
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how do brown fat cells utilize mit?
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uncouple oxidation from ATP synthesis
generates heat special transport protein allows H+ to move freely down gradient oxidation occurs more rapidly and energy dissipated as heat |
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how do symport carrier proteins work?
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energy for transport is derived from flow down an electrochem gradient in the SAME direction as transport
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how do antiport carrier proteins work?
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energy for transport is derived from flow down an electrochem gradient in the OPPOSITE direction as transport
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How do proteins get targeted to the outer mbn of the mit?
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hydrophobic sequence of protein inserts into membrane, then assumes its final conformation
NO cleavable signal sequence is required (except to mit proteins) |
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How do proteins get targeted to the matrix of the mit?
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Signal sequence is required.
1. proton gradient necessary. ATP hydrolysis provides energy 2. protein entry occurs at contact sites b/w outer and inner mbns, where proteins can cross both at once. proteins cross through translocases: -TOM complex - in outer mbn -TIM complex - in inner mbn 3. import requires HSP70 protein and ATP (used to release HSP70 after entry or cause conformational change in HSP70 to pull protein into mtx) |
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How do proteins get targeted to the inner mbn and intermbn space of the mit?
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Requires TWO signal sequences.
1. TOM/TIM23 cleaves 1st signal in mtx, which unmasks the 2nd hydrophobic sequence for the inner mbn 2. protein is released into free mtx and then reinserted into inner mbn OR 2nd seq is a stop transfer seq, leaving protein bound in inner mbn proteins for intermbn space are first inserted into inner mbn, then cleaved from 2nd signal by protease |
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what is the mit genome made up of?
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circular dsDNA in mtx, usual multiple copies
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what does mtDNA code for?
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2 rRNAs
13 proteins (subunits of resp enz complexes + ATP synthase) 22 tRNAs |
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who regulates mtDNA transcription, protein synth, DNA replication, and growth/division of mit?
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nucleus
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since there are only 22 mt tRNA's, what does this mean in terms of wobble?
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greater wobble because less tRNAs than in cytoplasm
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how does the mutation rate compare in mit?"
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10x greater mutation rate in mit
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what happens to mit in necrosis?
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1. calcium levels in cytosol increase, mit takes up calcium and water follows
2. mit swells/bursts, releasing toxic levels of Ca into cyto, activating enz that degrade cellular components 3. porins in outer mbn align with transport proteins in inner mbn, forming a mit permeability transition pore that releases Ca into cytoplasm |
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what happens to mit in apoptosis?
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requires ATP
cytochrome c is released from mit into cyto, forming complex w/ ATP, Apaf-1, and procaspase9 apoptosis triggered when inactive procaspase9 self cleaves to caspase 9 |
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what is parkinsonism?
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reduced fxn of respiratory enzyme complex in mit
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what is primary hyperoxaluria?
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improper targeting of peroxisomal enz to mit
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what is the endosymbiotic hypothesis?
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early prok cell internalized by anaerobic euk cell
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what tissues do heritable metabolic disorders of oxidative phosphorylation affect?
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tissues w/ high energy requirements
nervous sys, muscle, liver, kidney |
