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33 Cards in this Set
- Front
- Back
Who first hypothesized that lipids were an component of the cell membrane?
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Overton
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Who discovered that the cell was composed of a lipid bilayer?
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Gorter and Grendel
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Who proposed that the lipid bilayer was covered by protein sheets?
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Davson & Danielli
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Who first proposed the fluid mosaic model of cell membranes?
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Singer & Nicolson
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What are some membrane functions?
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1. Boundary and Permeable barrier
2. Organization and localization 3. Transport 4. Signal Detection 5. Cell to Cell communication as well as 6. Reaction site for many enzymes 7. Cell-to-cell adhesion 8. Cell-to-Extracellular matrix adhesion |
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The fluid mosaic model of cell membranes was supported using what microscopy technique?
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Freeze-Fracture electron microscopy
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True or False, both the lipids and proteins of a membrane are mobile?
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True
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What components of a membrane can vary between different types of cells?
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lipids
proteins carbohydrates in the form of glycoproteins or glycolipids |
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Describe membrane asymmetry.
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Differences between the two layers in both the kind of lipids present and the degree of unsaturation of the fatty acids in the phospholipid molecules.
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What does amphipathic mean?
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A molecule having spatially separated hydrophilic and hydrophobic regions
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What are the three different types of lipids present in the membrane?
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phospholipids
glycolipids sterols |
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Both phospholipids and glycolipids can have what two substances connecting their hydrophilic and hydrophobic regions
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glycerol
sphingosine |
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What is one of the functions of sterols, like cholesterol in the cell membrane?
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To stabilize the membrane at high and low temperatures.
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Blood groups are based on what type of membrane lipid?
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glycosphingolipids
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What two proteins use energy to move particular lipids from one monolayer to the other against a concentration gradient?
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Flippase and floppase
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The asymmetrical arrangement of lipids is established by what two membrane proteins?
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Flippase and floppase
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What membrane protein can move a variety of lipids down their concentration gradient without using energy?
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Scramblase
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During apoptosis what protein is activated triggering phosphatidylserine movement to the outer monolayer of the plasma membrane signaling surrounding cells to destroy it?
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Scramblase
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Why is it important for the membrane to remain fluid?
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To allow components (particularly proteins) to move about
Membrane fusion To prevent leakage |
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What factors can influence membrane fluidity?
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fatty acid chain length
degree of unsaturation of fatty acids amount of sterols which help stabilize the membrane at both high and low temperatures |
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How does a membrane with short unsaturated fatty acids handle temperature extremes?
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short unsaturated fatty acids will keep the membrane fluid in colds temperatures
in warm temperatures the membrane will become too fluid and leak |
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How does a membrane with long more saturated fatty acids handle temperature extremes?
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Long saturated fatty acids keep the membrane fluid in warm temperatures
in cold temperatures the membrane can become too rigid and crack |
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How many of the genes in the human genome code for membrane proteins?
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Nearly 30%
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What are the three types of proteins associated with the membrane?
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integral
peripheral lipid anchored or lipid linked |
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Which membrane proteins are at least partially embedded in the hydrophobic region of the membrane?
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integral
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Which membrane proteins are only bound to the outer surface of the membrane through weak electrostatic forces and hydrogen bonding with the hydrophilic ends of integral proteins or membrane lipids?
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peripheral
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Which membrane proteins are located on the surface of the lipid bilayer, but covalently bound to lipid molecules embedded within the bilayer?
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lipid anchored or lipid linked
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What does SDS stand for?
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sodium dodecyl sulfate
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What is the glycocalyx?
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the carbohydrate groups of plasma membrane glycoproteins and glycolipids which protrude from the cell surface and form a sugar coat
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How do cells maintain a shape that isn't spherical?
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Through the cytoskeleton and its connections to membrane proteins
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What is a membrane domain?
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an area of the cell that can maintain a specific protein composition that is distinct from the rest of the membrane
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How are membrane domains established?
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When specific proteins aggregate together
When some membrane proteins form barriers to others When cells form "tight junctions" that prevent the movement of membrane proteins When membrane proteins are anchored either to the cytoskeleton or the extracellular matrix |
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How does an intestinal cell demonstrate membrane domains?
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these cells have membrane proteins that transport substances out of the intestine and into the body, and these proteins are restricted to the the side of the cell where the transport is taking place
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