Lecture 15 11

Lecture 15 11 - /07/07 Mitochrondria and Chloroplast Beyond...

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Lecture 15 11/07/07 Mitochrondria and Chloroplast Beyond Secretory Pathway: Post Translational Protein Translocation – non-secretory, translated in the cytoplasm, protein transported to the final destination Organelles Nucleus – proteins that function inside nucleus go through post translational translocation (Nuclear envelope proteins are made in ER, then diffuse into envelope) o Proteins have NLS in primary amino acid sequence o Proteins are synthesized in cytoplasm, recognized by importin, brought through NPC to function in nucleus Peroxisome – function similar to lysosome o Break down toxic compounds that accumulate in cells, specifically small toxic molecules such as phenols or alcohols o Degrade these molecules through oxidation : generates H 2 O 2 (hydrogen peroxide) o “Garbage dump” of cell o Have a signal sequence similar to NLS or ER signal sequence called PTS – peroxisomal targeting sequence Found at C-terminus SKL Recognized by peroxins , a large group of proteins that recognize and import proteins in Proteins go through pore fully folded Mitochondria – “powerhouses” for the cell, present in most eukaryotic cells o Endosymbiosis Theory – Lynn Margulis Eukaryotic cells arose from anaerobic bacterial cells that engulfed an aerobic bacterial cell and this allowed the anaerobic cell to have the beneficial characteristics that then made it a eukaryotic cell! 1.) Anaerobic cell eat an aerobic cell (that aerobic cell became the mitochondria, gave it energy) 2.) Or SET…afterwards, cell eat a photosynthetic cell chloroplast Characteristics of mitochondria that provides reason why the theory arose: 1.) Organelles have a double membrane 2.) Own genome – small circular like bacterial genome 3.) Protein synthesis machinery (own ribosomes) 4.) Mitochondria and chloroplast come from pre-existing organelles (can’t spontaneously arise) o So basically, original eukaryotic cells come from prokaryotic cells engulfing other prokaryotic cells gave it the organelles that cell still has o Organelles (mitochondria, chloroplast) have own genome, but genomes are very
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This note was uploaded on 07/21/2008 for the course BICD 110 taught by Professor Mel during the Fall '06 term at UCSD.

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Lecture 15 11 - /07/07 Mitochrondria and Chloroplast Beyond...

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