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41 Cards in this Set

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what are the 3 functions of the plasma membrane of the cell?
1. to isolate the cell contents
2. to regulate what goes in and out
3. to communicate with other cells
in the fluid mosaic model of the plasma membrane, what molecules makes up the fluid part? the mosaic part?
fluid: phospholipids
mosaic: proteins
what do the ECF and the ICF have in common?
they are both watery
what part of the phospholipid is oriented toward the ECF? the ICF? why?
the hydrophilic heads are oriented towards the ECF
because they can hydrogen bond with water, which is polar
Why can phospholipids easily move about?
they arnt bonded together
why cant most molecules pass through the membrane easily?
because they are unable to dissolve in the hydrophobic fatty acids on the inside of the cell
do the phospholipids or the protein keep the molecules in or out?
the phospholipids
why do the plasma membranes need to be flexible
so they can be permiable, so plants and animals can move w/o breaking, allows them to flow and merge together
what molecule contributes to flexibility?
cholesteral
what are the 2 functions of the proteins embedded in the plasma membrane?
regulating what goes in and out and communication with other cells
what are the 3 catagories of membrane proteins?
transport proteins: regulate exhange either by carrier or channel proteins
receptor proteins: recieve messages that trigger chemical reactions
recognition proteins: allow cell to determine self from non self
whats the difference between carrier and channel proteins?
carrier:temporarily attatch to molecules, change shape to transport them
channel: allow small, water soluable (ions) to pass through memebrane
what molecules is attached to most recognition proteins?
glycoprotein
how does size of the concentration gradient affect the rate of diffusion?
the bigger the gradient, the faster it diffuses
when does diffusion stop?
where there is no longer a concentration gradient, or dynamic equilibrium
distinguish between active and passive transport
passive: move across membrane w/o any outside energy
active: requires and input of energy
which type of molecules cross using simple diffusion?
lipid soluable, small (H20 and O) can cross by simple diffusion
what 3 factors influence the rate of simple diffusion across a membrane?
1. concentration gradient
2. size of the molecule
3. how easily it dissolves in lipids
how is facilitated diffusion different from simple diffusion?
water soluable molecules can only diffuse wiht help from transport proteins
how do channel proteins differ from carrier proteins in terms of the type of molecules they assist in crossing the membrane?>
channel: assist ions
carrier: assist AA, sugars, or small proteins
does facilitated diffusion require energy?
NO it uses transport proteins, but uses no energy
what molecule crosses the membrane by osmosis?
water
Is the ECF isotonic, hypertonic, or hypotonic compared to the cytoplasm.
isotonic
although the type of dissolved substances in the ECF and ICF are different, what is teh same about the dissolved substanceS?
the total concentration of all dissolved substances is =
how can you make red blood cells shrivel?
by placing them in salt water. the cell would then by hypotonic (having less dissolved substances) so the water would flow out of the cell.
how can you make a red blood cell pop?
by placing it in water. the cell would be hypertonic in relation to the water (having more dissolve substances) so water would flow into the cell.
what 2 features are characteristic of active transport?
use energy to move molecules and moving against concentration gradient
describe 2 situations where active transport if vital to living things
plants and intenstines: w/o it we couldnt take up minerals
responsible for nerve cell funtioning, puts molecules back into cells
describe the structure of active transport
width of membrane
2 active sites
1)face of membrane, in contact with either ECF or ICF, binds molecule or ion
2)inside membrane, binds an energy carrying molecule, ususally ATP
what is the role of ATP in active transport?
donates energy to protein, causing it to change shape and move ion across the membrane
what types of substances enter a cell by endocytosis?
large proteins or entire microorganisms like bacteria
what types of substances enter a cell by exocytosis?
unwanted substances like waste or newly secreted homones leave cell
why do endo and exocytosis require energy when they are moving down a conentration gradient?
have to use the membrane to make vesicles and the have to replace the membrane
how are vesicles, coated pits, and food vacuoles associated wiht endo and exo cytosis?
vesicles: part of membrane, break off and contain fluid or particle
coated pits: depressions of the membrane
food vacuoles: responsible for bringing food into cell
what are two structures which may attach cells together?
desmosomes: attatch adjacent cells together
tight junctions: make leak proof, fuse together ex. urinary bladder
what are two structures that allow for cell to cell communication?
gap junctions: form channels that allow electric signals to pass
plasmodesmata: bridges inside of adjacent cells
what types of organisms posses cell walls AND membranes.
plants, protists, bacteria, fungi, archaea
what is the position of cell walls relative to the plasma membrane?
cell wall is on the outside of the plasema membrane
what is the function of cell walls?
to support and protect cell
what must be able to pass through cell walls?
small molecules: water, oxygen, minerlas, AA, sugars, etc
what plays a major role in governing the interactions between a cell and its neighbors? cell wall or plasma membrane?
plasma membrane