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17 Cards in this Set
- Front
- Back
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Key facts about membranes (3) |
- Bilaminar - Partially permeable - Double membranes in mitochondria and chloroplasts: envelope |
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Key components (3) |
- Amphipathic phospholipids - Proteins and glycoproteins - Cholesterol (animal cells only) |
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Draw and label fluid mosaic model |
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Effect of cholesterol in membrane |
- Can compose up to 50% of membrane - Reduces fluidity by reducing movement of phospholipid tails - Reduces permeability to some solutes |
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Difference in between saturated and unsaturated acids in membrane |
Saturated acid: less fluid, unsaturated: more fluid |
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Membrane protein types |
- Peripheral - Integral |
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Membrane protein functions (7) |
- Receptors (hormones, neurotransmitters) - Active transport - Facilitated diffusion - Electron carriers - Immobilized enzymes - Cell adhesion - Cell to cell communication |
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Davson-Danielli model |
- "Sandwich Model" - Based on observations of electron micrographs that showed two dark lines with a pale line in between - Stipulated that proteins coated both layers around phospholipids - Many problems: proteins exposed to hydrophilic surfaces on both sides, lipid soluble substances could not pass through |
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Singer-Nicholson model |
- Proposed much later: fluid-mosaic model - Supported by observations with a more powerful electron microscope - Proteins on surface but not as a continuous layer - Some went through the membrane |
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Simple diffusion |
- Substances move freely along the concentration gradient through membrane - Usually smaller molecules no ATP needed |
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Facilitated diffusion |
- Molecules that are too large to diffuse through membrane are able to pass through channel proteins that have a hydrophilic core. - Can be gated in order to control substance flow - Also passive transport does not require ATP |
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Osmosis |
Diffusion of water across a membrane, against the concentration gradient. Passive transport, does not use ATP. |
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Determining osmolarity |
- Cells placed in hypertonic solution will lose water and shrink - Cells placed in hypotonic solution will gain water and swell - Cells placed in an isotonic solution will remain the same |
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Kidney dialysis |
Uses partially permeable membrane to filter substances and replace functioning of Kidneys |
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Active transport |
- Uses ATP that is hydrolyzed into ADP + Pi - Transport against concentration gradient - Requires integral protein, such as K/Na pump - Has specific binding sites for certain substrates |
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Endocytosis |
- Taking substances into cell - Phagocytosis takes in particles - Pinocytosis takes in solutions - ATP required - Plasma membrane folds inward to form vesicle with substance |
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Exocytosis |
- Removes substances from cell - Includes secretion of useful substances and excretion of waste - Vesicle in cytoplasm joins membrane and bursts |
