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24 Cards in this Set
- Front
- Back
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Plasma membrane |
Flexible sturdy barrier that surrounds and contains the cytoplasm of a cell |
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Membrane lipids |
Allows passage of many types of lipid soluble molecules, but act as a barber to the entry or exit of charged or polar substances |
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What are the functions of the plasma membrane? |
1) acts as a barrier separating inside and outside of the cell 2) controls the flow of substances into and out of the cell 3) helps identify the cell to other cells 4) participates in intracellular signalling |
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Lipid bilayer |
Two back to back layers made up of three types of lipid molecules - phospholipids, cholesterol and glycolipids |
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Phospholipid, cholesterol and glycolipid percentage |
Phospholipid - 75% Cholesterol - 20% Glycolipids - 5% |
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Phospholipid |
Lipid containing phosphorus Hydrophillic head - polar Hydrophobic tail - non polar |
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Cholesterol |
Steroid with an attached OH group Weakly amphipathic molecules OH is the only polar region |
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Glycolipid |
Lipids with attached carbohydrates group Appear only in the membrane that faces ecf |
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Amphiphatic molecules |
Have a polar and non polar parts |
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Integral proteins
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Extend through/ into the lipid bilayer and are firmly embedded in it Most are transmembrane proteins - span the entire length of the bilayer Protrude into both cytosol and ECF |
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Peripheral proteins
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Not as firmly embedded into the membrane Attached to the polar heads of membrane lipids or to integral proteins |
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Glycoproteins
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Proteins with CHO groups attached to the ends that protrude into the ECF
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Glycocalyx
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Acts like a molecular 'signature' - enables differentiation Enables cells to adhere to one another in some tissues and protets cells from being digested by enzymes in ECF |
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Functions of integral proteins
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Form ion channels Act as carriers/ transporters Called receptors - each receptor binds a specific type of molecule Some are enzymes Serve as linkers that anchor proteins in the plasma membrane of neighbouring cells |
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Glycoprotein function
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Serve as cell identity markers
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Funtions of peripheral proteins
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Help support the plasma membrane Anchor integral proteins Participate in mechanical activities |
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What does membrane fluidity depend on?
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Depends on the number of double bonds in the fatty acid tail and On the amount of cholesterol present |
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What effect does double bonds have on membrane fluidity?
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Increases membrane fluidity by preventing lipid molecules from packing tightly
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What does membrane fluidity enable?
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Allows interactions to occur within the plasma membrane Enables the movement of the membrane components responsible for cellular processes |
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Membrane permeability
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Semipermable |
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The lipid membrane is highly permeable to...
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Non polar molecules
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Concentration gradient
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Difference in concentration of a chemical from one place to another E.g. inside to outside of the plasma membrane |
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Membrane potential |
Difference in electrical charges between two regions Also known as the electrical gradient |
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Electrochemical gradient
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The combined influence of the concentration gradient and electrical gradient on the movement of a particular ion
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