Flashcards in Text Chapter 3: Membranes Deck (25)
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Macromolecules that Comprise the Plasma Membrane
phospholipids, cholesterol, proteins
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Phospholipid Bilayer (plasma membrame)
forms boundary to isolate cell contents form environment, restricts passage of hydrophilic substances across the membrane
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Cholesterol (plasma membrane)
increases bilayer strength and flexibility, reduces membrane fluidity, reduces permeability to water-soluble substances
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Transport Proteins
regulates movement of water-soluble substances
Channel Proteins- have pores that allow passage of ions and small water-soluble molecules
Carrier Proteins- bind to molecules and change shape for delivery across membrane
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Receptor Proteins
docking site for molecules outside the cell, trigger internal cellular response
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Recognition Proteins
identification tags (carbohydrate chains aid in cell-cell recognition), cell-surface attachment sites
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Role of Carbohydrates when attached to Proteins and Lipids
carbohydrate chains aid in cell-cell recognition
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Diffusion
molecules move from an area of high concentration to an area of low concentration, molecules pass through the plasma membrane without the assistance of another molecule.
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Osmosis
diffusion of water molecules from an area of high concentration to an area of low concentration across a differentially permeable membrane
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Active Transport with Carrier
movement from an area of low concentration to an area of high concentration, energy and protein carrier required
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Endocytosis
surrounding the material with the plasma membrane, creating a vesicle that is transported into the cell, energy needed
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Receptor-Mediated Endocytosis
material that binds to a receptor is enclosed in a vesicle and transported into the cell
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Exocytosis
material enclosed in a vesicle is released from the cell when the vesicle fuses with the plasma membrane
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Hypertonic Solution
solute concentrations are higher in the extracellular fluid, water diffuses out of cells
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Hypotonic Solution
solute concentrations are lower in the extracellular fluid, water diffuses into the cells (unlike plant cells, animal cells may explode in hypotonic solutions because they don’t have a cell wall to limit cellular expansion)
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Isotonic Solution
solute concentrations are balanced, water movement is balanced
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Tight Junction
fusion of proteins from membranes adjacent to cells, form a water-tight seal between cells like a caulking around tub
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Desmosome
transmembrane proteins link together to bridge space between cells, act like velcro and fasten cells together
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Gap Junction (animals)
pairs of channels connect insides of adjacent cells (animals)
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Plasmodesmata (plants)
connect insides of adjacent cells (plants)
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Channel Proteins
have pores that allow passage of ions and small water-soluble molecules (type of transport protein)
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Carrier Proteins
bind to molecules and change shape for delivery across membrane (type of transport protein)
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Plasma Membrane "Fluid"
a double layer of phospholipids
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Plasma Membrane "Mosaic"
a collection of proteins
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