Cell Biol

Front 1

cell is a self reproducing system of mx's held inside a __________-a fatty thin and transparent film

Back 1

plasma membrane

Front 2

the plasma membrane's structure is based on a 2 ply sheet of lipid mxs ~ _____ thick

Back 2

5nm

Front 3

to facilitate exchange inward and outward of a cell, the membrane is penetrated by highly selective channels and pumps- ________ that allow specific substances to be imported while others are exported

Back 3

protein mx's

Front 4

the simplest bacteria have only a single membrane-

Back 4

plasma membrane

Front 5

In addition to the plasma membrane euk'ic cells have a profusion of __________ that enclose intracellular compartments (organelles)

Back 5

internal membranes

Front 6

the lipid component of membrane consists of many millions of lipid mx's arranged in 2 close sheets, forming a-

Back 6

lipid bilayer

Front 7

the ______ of membrane gives it its basic structure and serves as a permeability barrier

Back 7

lipid bilayer

Front 8

all cell membranes are composed of _____ and _____ and share a common general strcture

Back 8

lipids and proteins

Front 9

thin biomx'ar sheet of mainly phospholipid mx's that forms the structural basis for all cell membranes

Back 9

lipid bilayer

Front 10

describe the 2 main components of a lipid mx-

Back 10

1)hydrophilic (water loving) head
2)hydrophobic (water fearing) tail

Front 11

the most abundant lipids in cell membranes are the _________, mx's in whicht eh hydrophilic head is linked to the rest of the lipid thru a phosphate grp

Back 11

phospholipids

Front 12

most common type of phospholipid in most cell membranes is ____________, where the small mx choline attached to a phosphate as its hydrophilic head and 2 long hydrocarbon chains as its hydrophobic tails

Back 12

pohsphatidylcholine

Front 13

mx's with both hydrophilic and hydrophobic properties are termed-________, which play a crucial role in driving these lipid mx's to assemble into bilayers

Back 13

amphipathic

Front 14

fat mx are _______, whereas phospholipids are _______

Back 14

hydrophobic, amphipathic

Front 15

amphipathic phosopholipids form a ________ in water

Back 15

bilayer

Front 16

closed spherical vesiceles, called _________ form if pure phospholipids are added to water

Back 16

liposomes

Front 17

lipid mx's within a monolayer continuously exchange places with their neighbors, if this happens at a high rate (usually in higher temperatures) it is said to have a high _______

Back 17

fluidity

Front 18

the ease with which a cell membrane's lipid mx's move w/i the plane of the bilayer

Back 18

fluidity

Front 19

t/f the closer and more regular the packing of the hydrophobic tails of a amphipathic lipid, the more viscous and less fluid it will be

Back 19

TRUE

Front 20

what 2 major properties determine how tightly the hydrocarbon tails will be packed together in the bilayer-

Back 20

1)length
2)degree of unsaturation

Front 21

Hydrocarbon chain that harbors a dbl bond and not contain the max number of H atoms that it could in principle is said to be -

Back 21

unsaturated

Front 22

Hydrocarbon chain with no double bonds and has a full complement of H atoms is said to be-

Back 22

saturated

Front 23

t/f lipid bilayrs that contain a large proportion of unsaturated hydrocarbon tails are LESS fluid than those with lower proportions

Back 23

FALSE, MORE fluid, bc each dbl bond in an unsaturated tail creates a small kink in the hydrocarbon tail

Front 24

in animal cells membrane fluidity is modulated by the inclusion of the sterol- that fill the spaces b/t neighboring phospholipid mx's left by the kinks in their unsaturated hydrocarbon tails, stiffening the bilaryer making it more rigid and less permeable

Back 24

cholesterol

Front 25

what 4 reasons makes fluidity important in a lipid bilayer?

Back 25

1)allows membrane proteins to diffuse rapidly in plane of bilayer and interact w/ eachother
2) permits lipids and proteins to diffuse from sites where they're inserted into bilayer, after a synthesis in another part of the cell
3)allows membranes to fuse w/ one another and mix their mx's
4)ensures membrane mx's are distributed evenly b/t daughter cells when a cell divides

Front 26

cell membranes are generally ____________: they present a very different face to the interior of the cell or organelle than they show to the exterior

Back 26

asymmetrical

Front 27

enzymes that catalyze the transfer of lipid molecules to the opposite monolayer (from cytosolic monolayer to the opposite side)

Back 27

flippases

Front 28

class of lipid mx's that shows the most striking consistent asymmetric distribution in animal cells

Back 28

glycolipids

Front 29

in euk'ic cells nearly all new membrane synthesis occurs in one intracellular compartment-

Back 29

ER

Front 30

new membrane assembled in the ER is exported to other membranes of the cell through a cycle of -

Back 30

vesicle budding and fusion- bits of membrane pinch off from the ER to form small vesicles, wheich then become incorporated into another membrane by fusing with it

Front 31

type of lipids in animal cells that form part of a continuous surrounding protective coat of carbohydrate

Back 31

glycolipids

Front 32

glycolipid mx's acquire their sugar groups in the-

Back 32

Golgi apparatus

Front 33

are glycolipids found on the cytosolic or noncytosolic side of the lipid bilayer?

Back 33

on the noncytosolic side b/c they form the protective coat of carbohydrate that surrounds most animal cells

Front 34

these are minor components of the plasma membrane, that play a special role in relaying signals from the cell surface to the intracellular components that respond to those signals

Back 34

inositol phospholipids, concentrated in the cytosolic half ot he lipid bilayer

Front 35

most membrane fuctions are carried out by ________, where in animals, they constitute ~50% of th emass of most plasma membranes, the remainder being lipid plus relatively small amounts of carbohydrate-

Back 35

membrane proteins

Front 36

t/f bc lipid mx's are much smaller than protein mx's, a cell membrane typically contains about 50 times more lipid mx's than protein mx's

Back 36

TRUE, however protein's make up 50% of the mass of the membrane