Bio - Ch. 4

Front 1

what are the 3 functions of the plasma membrane of the cell?

Back 1

1. to isolate the cell contents
2. to regulate what goes in and out
3. to communicate with other cells

Front 2

in the fluid mosaic model of the plasma membrane, what molecules makes up the fluid part? the mosaic part?

Back 2

fluid: phospholipids
mosaic: proteins

Front 3

what do the ECF and the ICF have in common?

Back 3

they are both watery

Front 4

what part of the phospholipid is oriented toward the ECF? the ICF? why?

Back 4

the hydrophilic heads are oriented towards the ECF
because they can hydrogen bond with water, which is polar

Front 5

Why can phospholipids easily move about?

Back 5

they arnt bonded together

Front 6

why cant most molecules pass through the membrane easily?

Back 6

because they are unable to dissolve in the hydrophobic fatty acids on the inside of the cell

Front 7

do the phospholipids or the protein keep the molecules in or out?

Back 7

the phospholipids

Front 8

why do the plasma membranes need to be flexible

Back 8

so they can be permiable, so plants and animals can move w/o breaking, allows them to flow and merge together

Front 9

what molecule contributes to flexibility?

Back 9

cholesteral

Front 10

what are the 2 functions of the proteins embedded in the plasma membrane?

Back 10

regulating what goes in and out and communication with other cells

Front 11

what are the 3 catagories of membrane proteins?

Back 11

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

Front 12

whats the difference between carrier and channel proteins?

Back 12

carrier:temporarily attatch to molecules, change shape to transport them
channel: allow small, water soluable (ions) to pass through memebrane

Front 13

what molecules is attached to most recognition proteins?

Back 13

glycoprotein

Front 14

how does size of the concentration gradient affect the rate of diffusion?

Back 14

the bigger the gradient, the faster it diffuses

Front 15

when does diffusion stop?

Back 15

where there is no longer a concentration gradient, or dynamic equilibrium

Front 16

distinguish between active and passive transport

Back 16

passive: move across membrane w/o any outside energy
active: requires and input of energy

Front 17

which type of molecules cross using simple diffusion?

Back 17

lipid soluable, small (H20 and O) can cross by simple diffusion

Front 18

what 3 factors influence the rate of simple diffusion across a membrane?

Back 18

1. concentration gradient
2. size of the molecule
3. how easily it dissolves in lipids

Front 19

how is facilitated diffusion different from simple diffusion?

Back 19

water soluable molecules can only diffuse wiht help from transport proteins

Front 20

how do channel proteins differ from carrier proteins in terms of the type of molecules they assist in crossing the membrane?>

Back 20

channel: assist ions
carrier: assist AA, sugars, or small proteins

Front 21

does facilitated diffusion require energy?

Back 21

NO it uses transport proteins, but uses no energy

Front 22

what molecule crosses the membrane by osmosis?

Back 22

water

Front 23

Is the ECF isotonic, hypertonic, or hypotonic compared to the cytoplasm.

Back 23

isotonic

Front 24

although the type of dissolved substances in the ECF and ICF are different, what is teh same about the dissolved substanceS?

Back 24

the total concentration of all dissolved substances is =

Front 25

how can you make red blood cells shrivel?

Back 25

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.

Front 26

how can you make a red blood cell pop?

Back 26

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.

Front 27

what 2 features are characteristic of active transport?

Back 27

use energy to move molecules and moving against concentration gradient

Front 28

describe 2 situations where active transport if vital to living things

Back 28

plants and intenstines: w/o it we couldnt take up minerals
responsible for nerve cell funtioning, puts molecules back into cells

Front 29

describe the structure of active transport

Back 29

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

Front 30

what is the role of ATP in active transport?

Back 30

donates energy to protein, causing it to change shape and move ion across the membrane

Front 31

what types of substances enter a cell by endocytosis?

Back 31

large proteins or entire microorganisms like bacteria

Front 32

what types of substances enter a cell by exocytosis?

Back 32

unwanted substances like waste or newly secreted homones leave cell

Front 33

why do endo and exocytosis require energy when they are moving down a conentration gradient?

Back 33

have to use the membrane to make vesicles and the have to replace the membrane

Front 34

how are vesicles, coated pits, and food vacuoles associated wiht endo and exo cytosis?

Back 34

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

Front 35

what are two structures which may attach cells together?

Back 35

desmosomes: attatch adjacent cells together
tight junctions: make leak proof, fuse together ex. urinary bladder

Front 36

what are two structures that allow for cell to cell communication?

Back 36

gap junctions: form channels that allow electric signals to pass
plasmodesmata: bridges inside of adjacent cells

Front 37

what types of organisms posses cell walls AND membranes.

Back 37

plants, protists, bacteria, fungi, archaea

Front 38

what is the position of cell walls relative to the plasma membrane?

Back 38

cell wall is on the outside of the plasema membrane

Front 39

what is the function of cell walls?

Back 39

to support and protect cell

Front 40

what must be able to pass through cell walls?

Back 40

small molecules: water, oxygen, minerlas, AA, sugars, etc

Front 41

what plays a major role in governing the interactions between a cell and its neighbors? cell wall or plasma membrane?

Back 41

plasma membrane