CHP3 Cellular Form and Function

into organelles enzymes cytoskeleton supportive

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Unformatted text preview: rform metabolic tasks • Cells maintain order by compartmentalizing contents Cells (enzymes, synthesized products, etc.) into organelles (enzymes, • Cytoskeleton- supportive framework of cell • Intracellular (or cytosol) –vs- extracellular fluid extracellular Cell Surface Cell Cell Surface~ Cell • Plasma membrane- defines boundary of cell; controls defines interactions w/ adjacent cells; & controls movement of substances in/out of cell substances • ‘Fluid membrane’ since actually an oily film formed by a bilayer of phospholipids (+ lipids) w/ proteins enbedded bilayer • Cholesterol molecules ‘hold’ fatty acid tails in place • Glycolipids-phospholipids coat extracellular surface (glycocalyx) Membrane proteins~ • ~2% of p.membrane molecules are proteins…but include ~2% ~50% wgt of membrane ~50% Membrane Proteins Membrane Transmembrane proteins~ • Pass thru membrane (hydro-phobic/philic regions) • Glycoproteins that ‘float’ freely in phospholipid film • Some anchored to cytoskeleton Peripheral proteins~ • Adhere to surface of 1 side of membrane Functions: • • • • • • • Receptors 2-messenger systems Enzymes Channel proteins Carriers Cell-identity Cell-adhesion molecules Examples of membrane proteins Examples Glycocalyx= ‘fuzzy’ coat external to plasma membrane • Chemically unique layer of carbohydrates + glycoplipids & glycoproteins (identical twins have same composition) glycoproteins • Aides in identification of body’s own cells….self –vs- nonself distinction (transplanted organs/cells, diseased ir self cancerous cells, foreign pathogens, etc.) Microvilli, cilia, flagella Microvilli, Microvilli= surface extensions that increase surface area • Specialized for absorption (15-40x in intestinal tract, Specialized kidneys); sensory (taste buds, inner ear) kidneys); • Brush border= dense ‘fringe’ (mucus membrane) Cilia= hairlike projections, nonmotile (more common) & hairlike motile (respiratory tract & uterine tubes) motile • Beat in...
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