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62 Cards in this Set
- Front
- Back
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Membrane Functions |
1. Selective permeable barrier 2. Response to extracellular signals 3. Intercellular interactions 4. Formation of cellular extensions and pseudopodia 5. Contribute to gradient 6. Role in passive, active and bulk transport |
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What does selective permeable barrier mean?
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Regulation of passage of specific solutes i.e. permeable non polar uncharged molecules impermeable to polar and charged ions |
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What are forms of extracellular signals? |
hormones, ions, pharma, GF's cytokines, neurotransmitters |
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What cell juntion aids in passive, active and bulk transport ? |
Desmosomes |
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Why is anchoring to the cytoskeleton so important for the cell membrane? |
Gives the shape of the cell |
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Why is attaching to the extracellular matrix o important for the cell membrane? |
To help group cells together in the formation of tissues |
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What is a ligand? |
Ligand binds to a cell membrane receptor and is vital for cell signaling |
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What are the functions of intercellular interactions? |
Sealing and adhering Allows cells to recognize and signal each other To exchange materials and information |
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What are pseudopodia?? |
Temporary projections of eukaryotic cells Extend and contract by reversible assembly of actin subunits into microfilaments |
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What is the function of pseudopodia? |
Used for motion or for ingestion of nutrients i.e. phagocytosis or endocytosis |
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Angiogenesis |
The physical process through which new blood vessels from from pre-existing vessels |
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What happens in wound healing? and how is it associated with cellular extensions? |
Cells move, cells crawl via actin and microfilaments to gain entry to area of the wound |
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Chemotaxis |
Chemoattractant releases cytokines to promote movement of cells to the area such as neutrophils |
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What is an electrochemical gradient? |
concentration gradient with ions |
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How do ions want to move in their electrochemical gradient? |
They want to move down their gradient Towards the opposite charge found on the other side of the membrane |
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What is the result of the electrochemical gradient? |
Attraction to the other side of membranes can be harness to do work. i.e. membrane potential |
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Define bidirectional and give an example |
Transportation of molecules both in and out i.e. cell membrane |
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Passive transport examples |
Simple diffusion - diffusion and osmosis
Facilitated diffusion |
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Active Tranport examples |
Primary and secondary active transport |
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Bulk transport examples |
Solutes in ECF And engulfed Endocytosis and exocytosis |
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What type of molecules can do simple diffusion? |
Non polar - hydrophobic - lipophilic Fat soluble vitamins (A,D,E & K) Gases: O2 and Co2 and N2 Benzene |
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What factors influence the diffusion rate in simple diffusion? |
Steepness of the [gradient] temp mass of substances diffusing surface area diffusion distance |
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What molecules can do SOME simple diffusion? |
water, urea, glycerol, glucose and sucrose |
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Hypotonic solution |
Water will move into the cell causing lysis or turgidity |
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Hypertonic solution |
Water will flow out of the cell causing shrivelled or plasmolyzed |
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Isotonic solution |
Cell with maintain normal size or flaccid (plants) |
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Facilitated diffusion molecule examples |
Polar charged solutes - i.e. monosaccharides and some vitamins |
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What is facilitated diffusion? |
Is the flow of large molecules from an area of high to low concentration using proteins in the CM |
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What do you need for facilitated diffusion? |
Need transporters (cell membrane proteins) |
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Are the proteins for facilitated diffusion selective and why? |
Very selective Each transport protein transports just one type of molecule |
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More types of facilitated diffusion transporters? |
Acetylcholine and voltage gated sodium channels |
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Uniporter |
Integral protein that is involved in F.D. either a channel or carrier protein |
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Symporter |
Integral protein that moves two or more different molecules or ions Co transporter |
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Antiporter |
Secondary active transport of two or more different molecules or ions- opposite transfer of molecules |
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Primary active transport |
Requires energy to move substances for low to high concentrations |
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Where is the energy obtained in Primary active transport? |
ATP hydrolysis |
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What are some examples of primary active transport? |
Sodium potassium pump Calcium, hydrogen, chloride iodide urate a.a. sugars |
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Secondary Active Transport |
Energy stored in sodium or hydrogen gradient is used to drive other substances across the membrane against their own gradient |
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How are the sodium and H gradients established? |
Primary active transport |
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What type of porter is used in secondary active transport? |
Anti porters move sodium or protons in opposite directions across the membrane Sodium moves down its concentration gradient and the other molecule moves against |
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SGLT? |
Sodium glut transporter protein Pumps glucose from low to high using Na gradient |
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How would co2 cross the membrane? |
Simple diffusion |
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How would O2 cross the membrane? |
simple diffusion |
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How would glucose cross the membrane? |
Secondary active transport/ facilitated diffusion |
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How would chloride cross the membrane? |
Primary active transport |
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How would potassium cross the membrane? |
Primary active transport / potassium channels |
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How would fat molecules cross the membrane? |
Passive diffusion |
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What is alpa-tocopherol? |
Vitamin E |
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What are the three types of endocytosis? |
Phagocytosis Pinocytosis Receptor mediated endocytosis |
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Define Phagocytosis |
Cell eating cell engulfs large solid particles i.e. workout cells, bacteria, ciruses |
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What organelle does phagocytosis fuse with? |
lysosomes for degradation of the engulfed particle |
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Define Pinocytosis |
Cell drinking Tiny droplets of ECF are taken up Non-specific |
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What is an example of receptor mediated endocytosis? |
LDL particles attached to receptor to be taken up by the cell |
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What are the steps of receptor mediated endocytosis? |
1. Binding 2. Vesicle formation 3. Uncoating 4. Fusion with endosome 5. Recycle receptors to membrane 6. Degradation in lysosome |
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What is the transferring receptor used for? |
iron |
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What is transcytosis? |
Endocytosis on apical surface and exocytosis on the basolateral surface |
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What are some examples of transcytosis? |
Antibodies, Transferrin, Insulin |
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What cells is transcytosis common within? |
Epithelial cells and blood capillaries |
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What are some examples of receptor- mediated endocytosis mutation? |
Natural HIV immunity, familial hypercholesterolemia - Entrance of ligands is blocked |
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What is exocytosis? |
Exporting materials out of the cell by forming a membrane bound vesicle around the materials i.e. get ride of wastes, exportation of proteins made to be sent to another cell |
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Where does packing of membrane vesicles occur? and how? |
Golgi Vesicle merges with the cell membrane and the materials are released into the ECenvironment |
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Recyling membrane components from endosomes steps |
Internalisation Fusion with an internal membrane compartment Reincorporation into the plasma membrane very dynamic |
