Lec2_ProtSort_revised

Lec2_ProtSort_revised - Mitochondria, continued. Coupling...

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Coupling oxidative metabolism (proton gradient) with phosphorylation of ADP (ATP synthase) is a key step for ATP production. Uncoupling sometimes biologically useful. - The inner mitochondrial membrane in brown adipose tissue contains thermogenin (UCP-1, an uncoupling protein): forms alternative pathway for the flow of protons back to matrix. - This results in consumption of energy in thermogenesis (heat production) rather than ATP production. - useful when heat production required, for example in cold environments, newborns or hibernating animals. Synthetic uncouplers (e.g. 2,4-dinitrophenol ) also exist and can be very toxic. 1 Cell Biology – lecture 1 © Gross - all rights reserved. Mitochondria, continued….
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D103 Cell Biology – SS1 2009 Lecture 9+10 © Grün - all rights reserved. mitochondria actin DNA 2 Mitochondria are abundant and distributed throughout the cell
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Mitochondria are dynamic time Mitochondria move, fuse and divide! 3 Cell Biology – lecture 1 © Gross - all rights reserved.
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Mitochondria adapt to a cell’s energy requirement in respect to number, organization and shape 4 Cell Biology – lecture 1 © Gross - all rights reserved.
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Mitochondria contain DNA! nuclear DNA mitochondria mitochondrial DNA DNA, mitochondria, DNA + mitochondria 5 Cell Biology – lecture 1 © Gross - all rights reserved.
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Coordination of nuclear and mitochondrial genetic systems Mitochondria are NOT “self-sufficient”: •They require proteins encoded by nuclear DNA and imported from the cytosol into mitochondria, as proteins . 6 Cell Biology – lecture 1 © Gross - all rights reserved.
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Mitochondrial DNA • does not replicate in parallel to nuclear DNA during S-phase. • uses a different genetic code (4 out of 64 codons are different) • relaxed codon usage (22 tRNAs vs 30 tRNAs in the cytosol encodes only for a few of the proteins required for mitochondria function, and some mitochondrial rRNA and tRNAs • dense gene packing (little non-coding sequence) 37 genes 7 Cell Biology – lecture 1 © Gross - all rights reserved.
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Possible evolutionary pathway for the origin of mitochondria Endosymbiont hypothesis: When oxygen entered the atmosphere in significant amounts (1.5 billion years ago), primitive anaerobic cells engulfed the aerobic bacteria and subverted the bacteria’s oxidative phosphorylation system for its own use.
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This note was uploaded on 12/13/2011 for the course BIOSCI d103 taught by Professor Staff during the Fall '11 term at UC Irvine.

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Lec2_ProtSort_revised - Mitochondria, continued. Coupling...

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