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Ribosomes are bound by which part of mRNA?
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5' 7-methyl G cap
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What is a polysome?
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AKA polyribosome: one mRNA with multiple bound ribosomes - each translating its own protein.
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What type of proteins to free ribosomes/polysomes translate?What about ER-bound ribosomes?
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Free ribosomes --> cytoplasmic proteinsER ribosomes -->-membrane-bound-secreted-proteins destined for a specific organelle
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How much of the cell's volume can be composed of ER?
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Up to 10%
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What are the four functions of smooth ER?
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1) Carbohydrate metabolism (glycogen breakdown)2) Drug detoxification3) Muscle contraction (Ca++ sequestering)4) Phospholipid & cholesterol synthesis
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How does the ER package proteins destined for another site?
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-In vesicles-Coated with COPII protein, electron-dense coat-vSNARES determine which surfaces to bind to
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How many Golgi complexes can a cell have? (range)
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1-100 depending on cell type
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What are the two functions of the Golgi complex?
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1) Biochemical modification2) Macromolecular trafficking
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What 3 types of biochemical modification occur in the Golgi complex?
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1) Carbohydrate core of glycoproteins edited2) Cleavage of propeptides3) Enzyme localization in certain cisternae allows sequential modification (maintained there by retrograde flow)
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Where are lysosomes created?
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The trans-Golgi network
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How do proteins get signalled to lysosome?
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Tagged with mannose-6-phosphate
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What are residual bodies?
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Old lysosomes containing particles of digested material (lipofuscin)
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What are four types of secondary lysosome?
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1) Digestive Vacuoles (from phagocytosis)2) Late endosome (endocytosis)3) Autophagic vacuoles4) Multivesicular bodies
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What is a late endosome?
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An early endosome forms when a cell endocytoses a substance from cell exterior; becomes a late endosome when lysosomal enzymes go there.
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What is the function of a peroxisome?
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Carry out oxidation from H2O2-->catalase enzyme-->substrate-detox substances-break down fatty acids
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