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This 6 page Class Notes was uploaded by Mikaela Maldonado on Sunday October 18, 2015. The Class Notes belongs to LIFE 210 at Colorado State University taught by Paul J Laybourn in Fall 2015. Since its upload, it has received 37 views. For similar materials see Introductory Eukaryotic Cell Biology in Entomology at Colorado State University.
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Date Created: 10/18/15
Lecture 19 oz Eukaryotic Cell Compartmentalization gt Membranes organelles and organelle membranes Compartmentalize metabolic reactions and processes 0 Important for lysosomes toxins compartmentalized 0 Allow for proton gradients o Electrochemical gradientsactivepassive transport Provide compartment structure Are integral participants in processes gt Organelles Contain unique sets of proteins Have interior space Proteins and membrane lipids traf c between organees 0 Level of connectivity and interactions between the elements of the cell Organelles are epigenetically inherited No gene for individual organees 0 Not actually in the DNA for structure and placement Inherited from past ces gt Review of Compartments and Organelles Plasma membrane Cytoplasm Protein synthesis Metabolism Nuclear envelope 0 ER is continuous with the envelope Perinuclear space o In between the inner and outer membranes 0 Nuclear pore complex 9 Pores in the membrane complex Endoplasmic reticulum Ribosomes reside on the surface Golgi apparatus 0 Package and make the products for the cell Lysosomes RecycHng 0 Nutrient breakdown Transport vesicles 0 Carrying things around the cell compartments Mitochondria Oxidative ATP synthesis O 90 Peroxisome Fat and toxin breakdown Cytoskeleton Microtubules o Actin 0 Intermediate laments Inclusion bodies 0 Fat and starch storage Cellular proportions Cytoplasm is gt50 0 ER 15 0 Plasma membrane is 2 of all membranes 0 ER gt50 of all membranes Mitochondria 30 Clicker Question In the typical animal cell the cellular compartment present in the greatest number is gt The cytosol gt ER gt Nucleus gt Golgi gt Mitochondria In the typical animal cell the largest cellular compartment is gt The cytosol gt ER gt Nucleus gt Golgi gt Mitochondria Organelle Evolutionary Origins gt Golgi lysosome vesicles Increased surface area Concentration of enzymes gt Amoebas eating things got big Needed a better surface area to volume ratio Created a rounded shape with indentations to improve Enzyme secretions Vesicles could then be broken off and created to hold secretions within the cell gt Nucleus and ER Connected DNA attached to plasma membrane of ancient prokaryotic cell Invagination formed around the DNA attached to the plasma membrane Develops into eukaryotic cell with the nucleus structures Results in increased membrane area Concentrate enzymes gt Mitochondria and chloroplasts Aerobic prokaryotic cell absorbed into an anaerobic pre eukaryotic cell Engulfed cell turns to mitochondria surrounded by the cell membrane 393 Relationships between intracellular compartments gt Topology gt Three to four familes Nucleus and cytoplasm ER golgi lysosomes vesicles Mitochondria 0 Proteins synthesized here stay here or are synthesized in immediate cytoplasm Chloroplastsplastids gt Reducingoxidizing compartments oz Clicker Question The surface to volume ratio difference between eukaryotic and prokaryotic cells is about gt 2fold gt 5fold gt 10fold gt 20fold oz The lumen of the ER and the nucleoplasm are topologically equivalent to the exterior of the cell gt TrueFalse 393 Protein trafficking gt Proteins are synthesized on ribosomes in the cytoplasm gt Signal sequences direct to nucleus ER mitochondria gt Signal patches direct from Golgi to lysosomes gt Recognized by receptor proteins If a protein is a traveler a sortingtargeting receptor is A private car A taxi A bus An airplane A bike W009 oz Lecture 20 gt Into the ER and Outward Exocytosis amp The Plasma Membrane Inward Endocytosis gt Exocytic pathway Proteins destined for the ER Golgi plasma membrane and secretion Gated transport 9 Cytosol into the nucleus 0 Transmembrane transport 9 Cytosol into gt Peroxisomes gt mitochondria Vesicular transport Connected by vesicular transport Rough ER CoTranslational proteins 0 Proteins with N terminal signal sequences Smooth ER 0 Membrane lipid Vesicles bud off CA2 storage ER networks 0 Fluorescent protein marker localized Protein translocation into the Rough ER 0 Signal sequence on a growing polypeptide chain SRP receptor 0 Passed into a translocator complex o Ribosome sticks to the complex and then is translated into the membrane 0 Signal sequence is cut off and then is stuck in the membrane so then the protein is released and folded into the ER 0 Alpha helix stays connect to the membrane and also in the lumen 9 Can be multipass o Look at online videos under the module for further clari cation Some are kept unfolded and then stuffed through membranes 0 Step 1 translation 0 Step 2 bound to SRP receptor 0 Step 3 translocated into the lumen 0 Step 4 part of protein left in the membrane and the ribosome is released 393 The mechanisms of protein import into the ER and into the nucleus both gt Require the protein to be unfolded gt Are bidirectional gt Allow small molecule to pass freely through at all times gt lnvolve signal sequences that are removed after translocation gt Can occur posttranslationally o3 Membrane lipid synthesis in the Smooth ER gt Enzymes in cytosolic side of the ER membrane Lipid bilayer on the cytoplasmic side Sticks both tails on the glycerol side Sphinospine the heads are put on Fatty acyl tails and head groups added to glycerol and sphingosine backbones Scramblase Vesicular transport gt Coated vesicles Formation Membrane surface Clathrin plasma membrane coated coats is best understood 0 COPl golgiand COPII ER are the two additional types of vesicle formation Coated vesicle forms rst and then disperses after the vesicle is formed Golgi apparatus and membrane polarization ER to Golgi to plasma membrane secretory pathway Golgi to lysosomes plasma membrane to endosomes to the lysosomes endocytic pathway Vesicles continuously bud off and fuse Donor and target compartments Budding and fusing Many protein modi cations can occur Biosynthetic secretory Endocytic pathways Golgi apparatus gt Structure and organization gt Cis face ER gt Transface PM 420 cisternae quotstacksquot gt ER Sorting cis Phosphorylation of oligosaccharides on lysosomal proteins Removal of Man cis Removal of Man medial Additiaonl of GlcNAc Addition of Gal trans Addition of NANA trans Sulfation of tyrosines and carbs trans Sorting trans Go to lysosome plasma membrane secretory vesicle Process of decreasing pH VV VVV VVV O 90 Serial processing is the process Organized on microtubules Trans golgi network gt Sorted by aggregation and receptors gt Signal mediated diversion to ysosomes gt Mannose 6 phosphate receptor targets into vesicle into ysosome that serves as a receptor Signal mediated diversion to ysosomes Signal mediate diversion Constitutions and regulated secretory pathways Newly synthesized soluble proteins for constitutive The low pH of ysosomes protects the rest of the cell in case of ysosoma breakage by gt Rendering hydrolytic enzymes inactive in the cytoplasm VVV Membranes and vesicular transport are polarized gt Epithelial cells gt Endocytosis Transport from plasma membrane inward via late gt Four pathways converge on ysosomes by way of late endosomes M6P tagged proteins from ER via TGN Autophagy Endocytosis included pinocytosis or cellular drinking Phagocytosis or cellular eating gt Phagocytosis By protozoans and immune cells A macrophage ingests the equivalent of 100 of its plasma membrane through endocytosis every half hour gt Those cells exocytose The equivalent of 200 of their plasma membrane every hour Endosome population in polarized cells gt Early endosome sorting of endocytosed materials RecycHng Transcytosis Degradation Storage During transcytosis vesicles that form from coated pits on the cells apical plasma membrane then fuse the the plasma membrane of the basolateral surface false gt Everything goes through the endosomes and have to go through sorting