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47 Cards in this Set
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- Back
- 3rd side (hint)
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What is the mitochondria?
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The organelle in eukaryotic cells that contains enzymes for respiration and energy production. "Powerhouse of the cell"
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What shape is it?
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Can be thread like or granular.
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What is thought to be the evolutionary origin of the mitochondria?
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Symbiotic bacterial resident of primitive eukaryotic cells.
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How many membranes does it have?
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2; inner and outer. Inner membrane house proteins of electron transport chain.
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Other roles of the mitochondria (name three).
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Housing proteins that initiate apoptotic cell death.
Accumulating calcim to help shape spatial and temporal patterning of calcium signals which are key to cellular processes. Housing a number of synthetic enzymes e.g. those involved in steroid biosynthesis. |
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Does mitochondria have its own DNA?
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Yes, mtDNA is inherited maternally and important for mitochondrial function.
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State Mitchell's chemi-osmotic principle.
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Most ATP synthesis in respiring cells comes from the electrochemical gradient across the inner membranes of mitochondria by using the energy from NADH and FADH2 formed from the breaking down of energy-rich molecules such as glucose.
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Chemi-osmosis takes place in two stages via the electron transport chain. What is the elctron transport chain?
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Series of compounds within inner mitochondrial membrane that pass electrons from electron donors to electron acceptors via redox reactions.
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Chemi-osmosis takes place in two stages via the electron transport chain. What is stage 1?
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High energy electrons are transferred along a series of compounds from electron donor to electron acceptor via redox reactions. These electron transfers release energy that is used to pump protons (H+) from the intermembrane space, across the inner mitochonrial membrane and into the matrix. This creates an electrochemical gradient.
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Chemi-osmosis takes place in two stages via the electron transport chain. What is stage 2?
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H+ then flows back into intermembrane space through ATP synthase, thus catalysing production of ATP from ADP + Pi.
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What is the Kreb's cycle?
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It is a series of chemical reactions by which pyruvate is taken up, converted to acetate which is then oxidised. The cycle aims to reduce electron carriers NAD to NADH and FADH to FADH2. These electron carriers then transfer electrons t the ETC.
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What is complex I?
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aka NADH dehydrogenase.
Largest complex, 42 proteins. Oxidises NADH to NAD+. Accepts 2 e- from NADH and passes them to ubiquinone. Pumps 4H+ into the matrix from intermembrane space |
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What is complex II?
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aka succinate dehydrogenase
Made up of 4 protein subunit Runs parallel to complex I in passing electrons to ubiquinone. DOES NOT pump electrons into intermembrane space. Only complex to be entirely coded for by nuclear DNA. |
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What is ubiquinone?
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aka co-enzyme Q10; it transports electrons from complex I & II to III.
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What is complex III?
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aka cytochrome b-c1 complex
Made of at least 11 different polypeptide chains Passes electrons from ubiquinone to cytochrome C Pumps 4H+ (protons) into matrix from intermembrane space. |
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What is the role of cytochrome C?
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Transfer of electrons from complex III to complex IV.
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What is complex IV?
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aka cytochrome oxidase complex
Consists of 13 different polypeptides |
Acceptsacc
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How many mitochondrial proteins are encoded for by mtDNA?
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13 (complex II is only one that is not)
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Why is mtDNA maternally inherited?
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Oocyte contains many more mitochondria than sperm and sperm mitochondria are destroyed by oocyte after fusion.
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What diseases occur as a result of mtDNA mutation?
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CNS disorders, diabetes, deafness, blindness, seizures, lactic acidosis etc.
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Inheritance is Mendelial: true or false?
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FALSE, interitance is maternal.
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What is the role of calcium on ETC and TCA?
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Upregulates both.
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What is the result of a Ca2+ overload.
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Sustained opening of high conductance, cyclosporin A sensitive, permeability transition pore (PTP).
This causes collapse in membrane potential and swelling of mitochondria |
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Calcium is used as a secondary messenger to drive cell fate?
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TRUE
High mCa2+ --> pro-cell death Low mCa2+ --> autophagic rescue |
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Explain mitochondrial reperfusion injury.
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During ischaemia, Mt cannot respire and depolarise therefore they do not accumulate calcium.
Upon reperfusion, they are re-energised, depolarise and take up calcium which triggers cell death. |
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What is the MCU?
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Mitochondrial calcium uniporter.
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Describes structure of MCU.
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Made up of MCUa and MCUb.
Works at inner membrane and appears to be stressed ubiquitously. |
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What is the mPTP?
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Mitochondrial permeability pore; a large transmembrane pore with a very large conductance that allows loss of Ca2+.
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What a) opens b) inhibits and c) regulates the mPTP?
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a) High Ca2+, high Pi, ROS
b) ATP, CsA and SfA. Note CsA is cardioprotective and will reduce infarct size. c) Cyclophillin D. |
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What shape are mitochondria in: glia?
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Thread like in an interconnecting network.
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What shape are mitochondria in: neurons?
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Smaller, more discrete.
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What shape are mitochondria in: skeletal muscle?
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Aligned in pairs along Z-line.
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What shape are mitochondria in: cardiac muscle?
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Brick like and dense.
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What is PGC1-alpha?
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The master regulator of mitochondrial synthesis, up-regulation of it results in an increase of TFs NRF-1 and NRF-2 that upregulated pro-mitochondrial genes.
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In which disease will you find impaired PGC1-alpha.
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Huntington's disease.
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What is the effect of caffeine on mitochonria?
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Long term low doses = increased mitochondrial membrane potential.
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What is Drp-1?
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Controls mitochondrial fission
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What controls docking in mitochondrial fusion?
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Mfn 1/2
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What controls fusion of outer membrane?
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pH gradient across inner membrane and GTP
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What controls fusion of inner membrane?
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Membrane potential and high levels of GTP.
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Mitochondria and: Parkinson's like syndromes?
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Inhibitors of Mt complex I
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Mitochondria and: amylotrophic lateral sclerosis (ALS)?
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Mutant SOD localising to mitochondria
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Mitochondria and: cerebellar ataxia?
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Mutations in Drp1.
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Mitochondria and: Huntington's?
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Abnormal sensitivity to calcium overload and mutation in PGC1-alpha.
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Mitochondria and: Freidrich's ataxia?
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Mutation in protein required for iron transport in mitochondria required for haem.
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Mitochondria and: Alzheimer's.
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Amyloid beta causes mitochondrial dysfunction.
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What protein mediates fusion of the inner mitochondrial membrane?
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OPA 1
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