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7 Cards in this Set
- Front
- Back
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Mitochondria - Structure
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- organelles bound by double membrane
- matrix, Ph 8, 67% proteins, contains enzymes for citric acid cycle - Inner membrane, 21% proteins, highly folded into cristae to increase surface area, holds proteins for e- transport chain - outer membrane, 6% proteins, porins form large pores for permeable molecules to diffuse - inter-membrane space, pH 7, 6% proteins |
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Mitochondria - What do they do?
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- powerhouse of the cell
- produce energy in the form of ATP by oxidising products to produce CO2 and H2O - ATP: adenosine triphosphate, energy stored in phosphate bonds and released when they are broken |
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Mitochondria - How do they do it?
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- pyruvate is produced in the cytoplasm during glycolysis and transported into the matrix
- here they are converted into acetyl CoA and then fully oxidised in the citric acid cycle to produce NADH and FADH2 which act as e- donors to the e- transport chain |
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Mitochondria - electrochemical gradient
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- FADH2 and NADH are oxidised and pass the e- to complexes 1, 3 and 4 with increasing e- affinity, the final e- acceptor is oxygen (energetically favourable).
- ubiquinone and ctyochrome act as carriers between complexes - the energy released is used to pump H+ into inner membrane space, creating an electrochemical gradient - ATPsynthase sits in inner membrane and forms hydrophilic pathway for H+ to flow, H+ cause rotation and this mechanical energy is transferred into chemical energy as the stalk grinds against the head, forming ATP from ADP + P |
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Mitochondria - transport in and out
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- outer membrane is perforated with large pores formed by porin proteins which make it permeable
- O2 ad H2O can move freely down conc gradient across both membranes - the inner membrane has many channel proteins, pyruvate and Pi is transported by symport alongside H+ (in same direction using energetically favourable transport to aide unfavourable) - ATP and ADP are driven by a voltage gradient by antiport (in opposite directions) using an ATPexchange transporter. As ATP is more -ve it favourably moves into inter-membrane space which is more +ve, ADP is less negative so less unfavourable to move into matrix. |
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Mitochondria - proteins
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- encoded within the nucleus by cytosolic ribosomes
- chaperoned by hsp70 which keeps them unfolded while their N-terminal signal peptide targets them to the mitochondria - Translocases of the Outer (TOM) and Inner (TIM) Mitochondrial membranes mediate passage into the mitochondria (one or both depending on destination) - is post translational so needs energy |
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Mitochondria - DNA
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- has own genetic systems
- genomes are circular and vary in both size and the number of genes encoded - transcription/translation occur in the matrix and are carried out by complexes unique to the organelle - DNA is maternally inherited (this is due to the origins of mitochondria which are thought to have been bacteria which formed a symbiotic relationship with eukaryotic cell, this is further supported by there growth which is though division not synthesis from scratch) |
