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19 Cards in this Set
- Front
- Back
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Mitochondria Structure |
double membrane system - inner membrane and outer membrane separated by inter membrane space cristae - numerous folds of inner membrane matrix - interior of mitochondria, containing mitochondrial genetic system as well as enzymes responsible for: 1) Krebs 2) Beta Oxidation of FA 3) Pyruvate --> Acetyl CoA Inner membrane is principle site of oxidative phosphorylation and ATP generation |
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Genetic System of Mitochondria |
circular genomes, multiple copies per organelle encode tRNAs, rRNAs, and only a small number of proteins that are essential components of oxidative phosphorylation. Most mitochondrial proteins are encoded by nuclear genome Use slightly different code than "universal" genetic code used by prokaryotic and eukaryotic cells |
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Cellular Respiration |
C6H12O6 + O2 = CO2 + H2O + 36 ATP (1) Glycolysis (2) Krebs Cycle (3) Oxidative Phosphorylation |
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Glycolysis |
In cytoplasm glucose is converted to pyruvate Pyruvate --> Acetyl CoA (in mitochondria) |
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Krebs Cycle Citric Acid Cycle |
in matrix, production of high energy electrons in NADH and FADH2 Two carbons are oxidized --> CO2, and energy from these reactions is stored in form of NADH and FADH2 and some GTP synthesis of reducing nucleotides |
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Oxidative Phosphorylation |
electrons are transferred from NADH or FADH2 to molecular oxygen via electron transport chain proteins in inner mitochondrial membrane As a result of this flow of e-, H+ pumped from matrix to intermembrane space Generates a pH gradient --> potential energy -Proteins flow back to matrix via ATP synthase via chemiosmotic coupling (e- transport --> ATP) Glycolysis + Citric Acid Cycle + Oxidative Phosphorylation = 36 ATP |
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Porins |
proteins that form channels to allow free diffusion of molecules smaller than 1kD into highly permeable outer mitochondrial membrane import into mitochondria is posttranslational |
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Import into Mitochondria |
pre sequences are amino-terminal sequences of 20-35 aa that target protein to mitochondria Mitochondrial sequences are recognized by receptor on outer membrane and cleaved by matrix processing pepsidase (MPP) in matrix proteins complexes in inner and outer membrane coordinate TOM and TIM associate physically so protein can pass right through. Proteins must be a least partially unfolded, so members of Hsp70 proteins help in partial unfolding and translocation Additional mechanisms are in place besides MPP to direct proteins to correct submitochondrial compartment |
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Mitochondrial Diseases |
affect function of mitochondria and/or due to mitochondrial DNA Unique characteristics --> non mendelian, from mother. Critical to cell function. Becomes apparent only once the number of affected mitochondria reaches a certain level -Copies of DNA present are divided randomly, so if only a few copies are defective, may only end up in one mitochondria -Lack of error-checking capability Worst in muscles, cerebrum, and nerves --> need most energy |
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Diabetes Mellitus (DAD) Maternal Inherited Diabetes and Deafness (MIDD) |
mitochondrial disease associated with mitochondria defective gene |
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Leber's Hereditary Optic Neuropathy (LHON) or Leber Optic Atrophy |
mitrochondrially inherited degeneration of retinal ganglion cells (RGCs) and their axons that lead to an acute or subacute loss of central vision |
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Chloroplast |
Responsible for photosynthesis double membrane called chloroplast envelope thylakoid membrane forms network of flattened disks called thylakoids, arranged in stacks called grana. Inside thylakoid is thylakoid lumen\s Stroma is area between envelope and thylakoid membrane Gradient is against thylakoid membrane Green color is due to chlorophyll Have their own genetic code --> ~30 proteins in photosynthesis 3500/~95% of proteins still encoded by nuclear genes |
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Import of Proteins into Chloroplast Stroma |
Transit peptides are N-terminal sequences of 30-100 aa that direct protein translocation across the two membranes of chloroplast membrane A guidance complex initially recognizes the transit peptides and directs them to the translocase of chloroplast outer membrane - TOC complex: translocate of outer membrane - TIC : of inner membrane - Stroma Processing Peptidase (SPP) cleaves transit peptides from proteins imported to the chloroplast stroma |
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Plastids |
family of plant organelles that have DNA chloroplasts chromoplasts - lack chlorophyll but have carotenoids, responsible for yellow, orange, and red colors leucoplasts - nonpigmented, store energy in nonphotosynthetic tubular internal membrane in dark - thylakoid etioplasts - intermediate stage of chloroplast in which chlorophyll has not been synthesized amyloplasts - store starch elaioplasts - lipid storage development is controlled by both environmental signals and intrinsic programs of cell differentiation |
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Photosynthesis |
energy from sunlight harvested and used to drive glucose synthesis from CO2 and H2O 6CO2 + 12H2O + light --> C6H12O6 + 6O2+6H2O Light reaction in thylakoid Dark reaction in stroma Affected by CO2 concentration, light intensity, and temp |
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Electron flow through Photosystems I and II |
LIGHT REACTIONS PSI&II are multi protein complexes in thylakoid membrane involved in light reactions Starts at PSII. Chlorophyll absorbs light and loses a high energy e- that travels down chain to create gradient Chlorophyll regains its e- by taking an O from H2O. For every pair of e-, H+ transferred across thylakoid membrane at cytochrome bf complex. Oxidation of H2O --> protein gradient which drives ATP synthesis (when gradient reaches critical value - ATP synthase-->ATP) Produces NADPH but upon cyclic flow can make ATP if needed |
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Cyclic Electron Flow |
From PSI Produces ATP without NADPH Oxygen is only PII NADPH --> PI Used in dark reaction for sugars |
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Light Independent Reaction |
dark reaction / Calvin Benson Cycle Use high energy molecules produced in first phase to capture carbon dioxide (CO2) and make 3-carbon sugars which are later combined --> glucose --> Dark Reaction is affected by light intensity because light reaction is "Carbon Dioxide Capture" --> 1 molecule of glucose |
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Peroxisomes |
small, single membrane enclosed organelles that contain enzyme involved in a variety of metabolic reactions 50 different enzymes: oxidative --> catalase (decompose H2O2) 2H2O2--> 2H2O + O2 eliminate poisonous hydrogen peroxide detox toxic substances in blood Breakdown of Long FA Molecules --> beta oxidation (in animals and mitochondria) (yeast & plant --> exclusive for peroxisome) Proteins are selectively imported in. Peroxisome Targeting Signals (PTS) Peroxins - peroxisomal proteins (32 of them) participate in process of importing peroxisomal proteins in ATP and peroxisome assembly --> lipid metabolism --> Zellweger Syndrome: brain. Pex2 - one form of syndrome. Or milder --> lack of recognition signals |
