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Cell Size/Transport
| Question | Answer |
|---|---|
| cell size - what depends on it? (1) what must leave? (1) what does it dissipate? (1) what must enter? (2) what happens at a certain size? | cellular metabolism; cellular waste must leave; thermal energy; nutrients and other resources/chemical materials; too difficult to regulate what comes in/goes out of the plasma membrane |
| surface area to volume ratio - size & function? (1) what kind of SA:V ratio do cells need? why? (1, 1) | the size of a cell will dictate its function; high SA:V ratio to optimize the exchange of materials through the plasma membrane |
| what kind of SA:V ratio do small cells have? why? (1, 1) vice versa? (1, 2) what increases (1) and decreases (1)? | small = HIGH SA:V ratio, optimizes exchange of materials at the plasma membrane; larger = LOWER SA:V ratio, lose efficiency exchanging materials, cellular demand for resources INCREASES, rate of heat exchange (dissipation) DECREASES |
| what are the structures of a phospholipid? (4) | phosphate group (P, O group); glycerol (CH2 group); hydroPHILIC head; hydroPHOBIC tail |
| how do you determine if a phospholipid has a saturated fatty acid or an unsaturated fatty acid? | a saturated phospholipid has rigid, straight hydrophobic tails with hydrogens. however, an unsaturated phospholipid has a double bond |
| why are the heads of a phospholipid hydrophilic? (1) | oxygens can form hydrogen bonds with other water molecules because water is polar |
| plasma membrane - main purpose? (1) comprised of? (1) what regions? (2) what does it form? (1) | separates internal cell environment from external environment; comprised primarily of phospholipids; hydroPHILIC + hydroPHOBIC; forms a bilayer |
| Phospholipid bilayer - describe the head and tails (1, 1) what term is the plasma membrane (two words), and why? (1) | polar hydrophilic heads (phosphate regions) are oriented towards aqueous environments; non-polar hydrophobic tails (fatty acid regions) are facing inwards away from aqueous environments; hydrophobic interior causes selective permeability of membrane |
| what does it mean that the plasma membrane is selectively permeable? (1) due to what? (2) what kinds of transport? (2) | selective permeability is the ability of membranes to regulate the substances that ENTER/EXIT, due to hydrophobic interior, non-polar hydrophobic tails; can be through active or passive transport |
| what is the fluid mosaic model? | describes the structure of cell membranes |
| what is the fluid in the "fluid mosaic model" specifically for structure? (4) | weak hydrophobic interactions hold the membrane together and therefore it moves and shifts; temp affects fluidity; unsaturated hydrocarbon tails maintain fluidity at LOW temps; kinked tails prevent tight packing of phospholipids |
| what is the importance of CHOLESTEROL in the fluid aspect of the "fluid mosaic model"? (3) what does the mosaic aspect mean? (1) | helps maintain fluidity at both high/low temps; high temp reduces movement; low temp reduces tight packing of phospholipids; comprised of many MACROMOLECULEs |
| Membrane Proteins - what are the categories of membrane proteins? (2) | integral and peripheral |
| Integral proteins - what are they? what region can they be (3) | proteins embedded into the lipid bilayer; can be hydrophilic/phobic, or both; determined by side chains (r-groups) |
| Integral proteins - hydrophilic regions (3) v. hydrophobic regions (3) | charged/polar side chains, make up the interior of the channel/pore, exposed to cytosol /// nonpolar side chains, make up protein surface, interact with fatty acids on the interior of the membrane |
| peripheral proteins (2) | proteins that ARE NOT embedded into the lipid bilayer; loosely bonded to the surface |
| membrane carbohydrates - why are they important? (1) glycolipids (1) v. glycoproteins (2) | important for cell-to-cell recognition; glycolipids - carbs bonded to LIPIDS; glycoproteins - carbs bonded to PROTEINS, most abundant |
| some substances can cross the membrane more easily than others. EASY PASSAGE v. DIFFICULT PASSAGE | small, nonpolar hydrophobic molecules (hydrocarbons, CO2, O2, N2) ; hydrophilic molecules, large molecules, ions; WHY: nonpolar hydrocarbon tails have a huge impact on what comes in/comes out |
| Cell walls - what do they cover? (1) ex? (4) functions? (3) | plasma membranes (bacteria, archaea, fungi, plants); provide structural boundary (defines/supports cell's shape); permeability barrier for some substances; protection from osmotic lysis (cell bursting when excess water goes into cell) |
| Plants - cell walls - composed of what? (1) thinner or thicker than what? (1, 1) what does it contain? (1) what is it? (1) | composed of cellulose; thicker than plasma membranes; contain plasmodesmata: hole-like structures in the cell wall filled with cytosol that connect adjacent cells |
| what is active transport? what is passive transport? | requires cellular energy to pass materials through membrane; the opposite |
Created by:
i.lundin