Endomembrane System and Cytoskeleton Vocab Notes

• Endomembrane System and cytoskeleton
• Membrane: A pliable sheet-like structure acting as a boundary, lining, or partition in an organism
• Always enclose a space (cisterna or vesicle)
• Never open ended unless damaged
• Biological membranes move from T-junctions
• Consistency of olive oil in water, therefore no stiff barriers
• Endomembrane System: System of compartments that generally includes all of the membrane-bound components of the cell (including the nuclear envelope) except for the mitochondria and chloroplast
• Cisternae: Flattened, fluid filled tubules within the cell
• Endoplasmic Reticulum: Network of membranous sacs extending throughout the cytoplasm of a eukaryotic cell (usually flat and sheet like but can be linked by tubular cisternae). Rough ER → Smooth ER
• Membrane cisternae that ramify through the cytoplasm. The result is internal compartments and channels 
• Provides surfaces for the synthesis of proteins, lipids and carbohydrates.
• Connected to nuclear envelope
• Rough ER: Endoplasmic reticulum with attached ribosomes and involved the synthesis of proteins to be exported from a cell
• Smooth ER: Lacks attached ribosomes
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• Golgi Apparatus: Stacks of four to ten disc shaped cisternae functioning in the synthesis of polysaccharides, glycosylation of proteins and the sorting of molecules for storage or secretion
• Golgi Stacks: functional extensions of the ER and are polar structures
• All the polysaccharide in cells is manufactured within the Golgi apparatus
• Polysaccharide may be attached to either protein or lipid molecules in the golgi stacks
• Functions in the collection, packaging, and distribution of molecules synthesized elsewhere in the cell
• Lysosomes: Membrane-bound component of a cell containing hydrolytic enzymes involved in the breakdown and recycling of many types of molecules → attached to the golgi apparatus
• Single membrane bound
• Autophagy: A process where cellular material becomes enclosed in a double membrane and degraded (macromolecules broken down into protein, carbohydrate, lipid and nucleic acid)
• Acidic interior containing specialized enzymes
• Microbodies: Main organelles for removing compounds generated within the cell
• Surrounded by one membrane
• Neutral pH: contain oxidative enzymes that generate hydrogen peroxide and the enzyme catalase to break down the hydrogen peroxide
• Spherical in shape and contains crystalline inclusions  
• Peroxisomes: Type of microbody contains enzymes and is involved in the production and degradation of peroxides and oxidation of amino acids and uric acid
• Glycoxysomes: Contains 5 enzymes and is involved in the conversion of fatty acids into sugars
• Plant Vacuoles: Plant version of lysosomes
• Tonoplast: single membrane
• Contains hydrolytic enzymes and serves as degradative compartments
• Storage of nutrients, pigments and maintenance of cell turgor pressure
• Cytoskeleton: Network of microtubules, microfilaments (actin) and intermediate filaments (eukaryotic cell)
• Act as a form of scaffolding or as structural elements within the cytoplasm of cells, and are associated with maintaining cell shape
• Movement of organelles within the cytoplasm and cell movement
• Composed of PROTEIN not membrane
• Microtubule: Hollow protein filament composed of tubulin proteins (tubulin sub units)
• Actin Filament: Globular protein (actin sub units)
• Form stiff structures that do not branch or contract
• Polymerize and depolymerize to satisfy the cells needs
• Polar and highly dynamic structures
• Intermediate filament: Provides mechanical support to the cell. Intermediate in size between microtubules and microfilaments

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