Term
| Stages of food break down |
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Definition
1) In Gut
- Break down of macromolecules into subunits
2) In Cytosol
- Break down of simple subunits to Acetyl CoA accompanied by limited production of ATP and NADH
3) In Mitochondria
- Complete oxidation of Acetyl CoA to H2O and CO2 accompanied by high production of ATP |
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Term
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Definition
Starch, glycogen, fat can store lots of energy in small volume without creating osmotic pressure and causing influx of water
Hydrolysis of starch/glycogen -> glucose for glycolysis
Fatty acid oxidation -> each turn of cycle gives 1 molecule of Acetyl CoA, NADH, FADH2 |
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Term
| Explain process of glycolysis |
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Definition
Glucose is not reactive, 2 ATP needed to start glycolysis.
Glucose + 2 ATP -> fructose 1,6 biphosphate
Fructose 1,6 biphosphate cleaved into glyceraldehyde 3-phosphate (6-C to 2 3-C molecules) and also yields 2 pyruvates, 4 ATP, 2 NADH.
Net gain: 2 ATP + 2 NADH |
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Term
| Explain ATP production by fermentation |
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Definition
Anaerobic respiration, no oxygen
1) Lactic acid fermentation
- Pyruvate -> lactate, NAD+ regenerated to further drive glycolysis
- Lactate carried by blood back to liver where it is reconverted to pyruvate, which is broken down in citric acid cycle.
2) Pyruvate -> ethanol, regenerates NAD+.
- Accumulation of alcohol eventually stops reaction |
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Term
| How is Acetyl CoA produced? |
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Definition
- Pyruvate converted to Acetyl CoA in mitochondrial matrix.
- Fatty acids also converted to Acetyl CoA in mitochondrial matrix.
- Some amino acids are deaminated and also yield Acetyl CoA |
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Term
| Mitochondrial characteristics |
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Definition
- Consists of 2 membranes, 2 compartments
Mitochondrial matrix contains circular DNA molecules that lack histones, about 5 microns long.
Mitochondria contain ribosomes, synthesize a few proteins |
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Term
| Levels of centrifugation and what they yield |
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Definition
Low speed: whole cells and nuclei
Medium speed: mitochondria, lysosomes
High speed: microsomes (ER membranes that have broken and re-sealed) and small vesicles
Ultra high speed: viruses, ribosomes, large macromolecules |
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Term
| How were mitochondrial nucleic acids discovered? |
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Definition
Cells embedded in water-soluble plastic were treated in DNase solution which dissolved the fibrils.
Fluorescent staining confirmed existence of Mito DNA
- Mitochondrial ribosomes smaller than cytosolic ribosomes.
- Translation is blocked by same antibiotics that block translation in prokaryotes (indicate prokaryotic origins) |
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Term
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Definition
Porins are beta barrel proteins that form water-filled channels in the outer mitochondrial membrane.
- Molecules up to 5,000 daltons pass through.
- Protons readily pass through porins |
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Term
| What is Acetyl CoA used for? |
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Definition
Citric acid cycle breaks down Acetyl CoA in mitochondrial matrix.
- 2 carbons of acetyl group in Acetyl CoA released as CO2. (Water supplies oxygen for CO2)
- 1 GTP produced, can be used or phosphorylate ADP to ATP
- 3 molecules of NADH, 1 molecule of FADH2 (high energy electron carriers) |
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Term
| Summary of glycolysis, citric acid cycle, oxidative phosphorylation |
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Definition
Glycolysis: 1 glucose -> 2 pyruvate + 2 ATP + 2 NADH
Citric acid cycle: NADH & FADH2 produced, drive oxidative phosphorylation of ADP -> ATP. NADH from glycolysis also used.
- CO2 released, CoA released |
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Term
| Purpose of NADH and FADH2 |
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Definition
Electron transport chain
- Hydride ion removed from NADH (proton and 2 e- result)
- Electrons pass through ETC in inner mitochondrial membrane (IMM), proton gradient generated to phosphorylate ADP to ATP.
- Used electrons combine with proton and oxygen to make water.
Resulting NAD+ and FAD can be reused in citric acid cycle. |
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Term
| Enzyme complexes in Electron Transport Chain |
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Definition
Electrons pass through these complexes.
1) NADH dehydrogenase complex
- dehydrogenates NADH
2) cytochrome b-c1 complex
- pumps protons out
3) Cytochrome oxidase complex
- pumps protons out
- water formed
All these complexes pump protons into intermembrane space and out of matrix so proton gradient and membrane potential are pushing protons back into matrix, drives protons through ATP synthase. |
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Term
| What are Ubiquinone and cytochrome c? |
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Definition
Mobile electron carriers
- Ubiquinone carries 2 electrons and 2 protons from NADH dehydrogenase to cytochrome b-c1 complex.
- Cytochrome c loosely bound to inner mitochondrial membrane, carries 1 electron from cytochrome b-c1 to cytochrome oxidase complex. |
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Term
| Evidence for existence of ATP synthases |
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Definition
- Not seen through TEM sections of inner mitochondrial membranes
1) Electron-dense stain added to IMM (negative staining)
2) Stain dries around ATP synthase
3) ATP synthase seen as 10nm diameter globular structure |
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Term
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Definition
Mitoplast vesicles from mitochondria
- have ATP synthase on outside, interior equivalent to intermembrane space
- able to phosphorylate ADP when NADH added.
No ATP synthase -> no ADP phosphorylation |
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Term
| ATP synthase structure and rate |
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Definition
Composed of stator and rotor.
- Protons pass through narrow channel where stator meets rotor, causes rotor to rotate.
- Rotor pushes against proteins of hexamer head
- Mechanical movement creates ATP
Rate: more than 100 ATP/sec |
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Term
| How was ATP synthase demonstrated in action? |
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Definition
1) ATP synthase removed from IMM
2) Fluorescent actin filament attached to end of rotor
3) ATP added to rotor, actin rotated at 4 revs/sec
4) hydrolysis of ATP by hexamer head caused rotor to rotate (normally synthase uses proton flow to drive rotation) |
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Term
| Permeability of IMM (Inner Mitochondrial Matrix) |
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Definition
IMM normally impermeable to protons (need for electron transport chain to pump out and ATP synthase to re-enter)
- CARDIOLIPIN forms 20% of IMM membrane, important in membrane impermeability.
- UNCOUPLING AGENT in IMM makes IMM permeable to protons, inhibits ATP synthesis.
- Brown fat cells have natural uncoupling agent. (energy of protons re-entering matrix is released as heat) |
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Term
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Definition
Sealed vesicles spontaneously formed by phospholipid bilayers. (similar to mitoplasts)
- Bacteriorhodopsin pumps protons into interior
- ATP synthase pumps them out, ATP generated.
- Uncoupling agent still releases protons, no ATP generated. |
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Term
| What drives bacterial flagellar motor? |
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Definition
Proton flow.
Proton pump pushes protons into inter-membrane space, flow causes flagellar motor to rotate. |
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Term
| Coupled transport across IMM |
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Definition
Symports: (driven by pH gradient)
- Pyruvate and protons
- Phosphate and protons
Antiport: (driven by voltage gradient)
- ADP enters, ATP exits |
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Term
| How much energy released from complete oxidation of glucose? |
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Definition
30 ATP molecules.
- 2.5 ATP per NADH (10 NADH total)
- 1.5 ATP per FADH2 (2 FADH2 total)
- 1 ATP per GTP (2 GTP total)
Glycolysis:
- 2 NADH & 2 ATP
Pyruvate oxidation to Acetyl CoA:
- 2 NADH
Complete Acetyl CoA oxidation:
- 6 NADH, 2 FADH2, 2 GTP |
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Term
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Definition
Codes for 2 rRNAs, 22 tRNAs, 13 mRNAs.
- Lacks histones
Mito diseases: Leber's Hereditary Optic Neuropathy (caused by single base change in NADH dehydrogenase) |
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Term
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Definition
| All OXPHOS enzymes contain proteins coded by both nuclear and mitochondrial genes |
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Term
| Protein import into mitochondria |
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Definition
Nuclear-encoded mito proteins (produced in cytosol) are translated on polysomes, become associated with chaperone proteins which prevent protein from folding.
- Import signal recognized by receptor protein on OMM
- Receptor moves laterally to protein translocator site
- Translocator moves protein from OMM to IMM
- Import signal removed by signal peptidase
Import also requires: proton gradient across IMM, ATP, and chaperone in matrix to enable protein folding.
PROTEIN FOLDING: YES OR NO??? |
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Term
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Definition
Mitochondria import most of their lipids.
Phospholipids, Phosphatidylcholine and Phosphatidylserine made on ER and transported to mitochondria.
- Some imported lipids converted to cardiolipin in mitochondria. Cardiolipin has 4 phospholipid tails, helps to make IMM impermeable to protons, forms 20% of IMM lipid. |
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