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Chapter 7 Biology
Membrane structure and function
| Question | Answer |
|---|---|
| What does an Amphipathic molecule contain? | hydrophobic and hydrophilic regions |
| What is an Aquaporin and what does it do? | they are channel proteins and they facilitate the passage of water |
| What is the process of diffusion? | to spread out evenly into the available space, each molecule moves randomly |
| What is it called when as many molecules cross one way as cross in the other direction? | dynamic equilibrium |
| Explain how the fluid mosiac model of the membrane structure. | states that a membrane is a fluid structure with a "mosaic" of various proteins embedded in it |
| Explain how membrane fluidity is influenced by temperature and membrane composition. | With cooling, it switches from a fluid state to a solid state. At cooling, it maintains fluidity by preventing tight packing. At warm degrees, cholesterol restrains movement of phospolipids |
| What is the main thing to know about membrane fluidity? | They must be fluid to work properly. |
| What is it called when it's bound to the surface of the membrane? | peripheral membrane proteins |
| What is it called when they are penetrating the hydrophobic core? | integral Membrane proteins |
| What is another term for channel proteins? | aquaporins |
| What is it called when molecules are bind and change shape just to shuttle them across the membrane? | carrier proteins |
| What is it called when there is a diffusion of water across a selectively permeable membrane? | osmosis |
| What is the process of osmosis? | when water diffuses across a membrane from the region of a lower solute concentration to the region of a higher solute concentration |
| What is it called when it is still passive because the solute moves down its concentration gradient? | facilitated diffusion |
| What does Active Transport do? | it moves substances against their concentration gradient, requires energy, usually in the form of ATP, and is performed by specific proteins embedded in the membranes |
| What is it called wen solute concentration is greater than that inside the cell; cell losing water? | hypertonic |
| What is it called when solute concentration is less than inside the cell; cell gains water? | hypotonic |
| What is it called when solute concentration is the same as that inside the cell; no net movement across the membrane? | isotonic |
| Explain how large molecules are transported across a cell membrane. | they cross the membrane in bulk-aka vesicles |
| What is the major structural components of the cell membrane? | phospholipids and proteins |
| The presence of cholesterol in the plasma membranes of some animals what? | makes the membrane less flexible, allowing it to sustain greater pressure from within its cell |
| In order for a protein to be an integral membrane protein it would have to be which of the following:a.hydrophilic b.exposed on only one surface of the membrane c.hydrophobic d.amiphipathic e.completely covered in phospholipids | hydrophobic |
| When a membrane is freeze-fractured, the bi-layer splits down the middle between the two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane, the bumps seen on the fractured surface of the membrane are what? | integral proteins |
| Which of these is not embedded in the lipid bilayer at all? a.integral proteins b.integrins c.peripheral proteins d.transmembrane proteins e.glycoproteins | peripheral proteins |
| What kind of molecules pass through a cell membrane most easily? a.large polar b.ionic c.small and hydrophobic d.monosaccharides like glucose e.large and hydophobic | small and hydrophobic |
| Water passes quickly through cell membranes because? a.it's a small, polar charged molecule b.the bilayer is hydrophilic c.water movement is tied to ATP hydrolysis d.it moves through aquaporins in the membrane e.it moves through hydrophobic channels | it moves through aquaporins in the membrane |
| After the system reaches equilibrium, what changes are observed? | the water level is higher in side A than in side B |
| What would be a huge factor that would increase the membrane fluidity? | a greater proportion of unsaturated phospholipids |
Created by:
RosauraPerez
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