Plasma Membranes

Question 1

what compound allows animal cells to exist without a cell wall.

Answer 1

cholesterol within the phospholipid layers

Question 2

what does cholesterol within the phospholipid lipid layers do?

Answer 2

it creates a rigid and impermeable cell wall in animal cells

Question 3

what are transmembrane proteins?

Answer 3

proteins that cross both layers of the bilayer
they are integral
they generally cannot leave

Question 4

what role do many transmembrane proteins play within the cell?

Answer 4

many are carrier or channel proteins

Question 5

what are peripheral proteins?

Answer 5

they only interact with the membrane temporarily and can interact with the phospholipid bilayer or attach to a transmembrane protein

Question 6

what can peripheral protein interactions cause?

Answer 6

different responses e.g. tell a transmembrane channel to close - which is important to cell signalling

Question 7

what is the extracellular matrix?

Answer 7

the surroundings of an animal cell that consists of glycoproteins, polysaccharides and other things.

Question 8

what does interstitial mean?

Answer 8

connects between nearby cells that arent attached to each other

Question 9

can the extracellular membrane be interstitial?

Answer 9

yes

Question 10

what is a base membrane?

Answer 10

a base that cells can be attached to giving them strength and stability.

Question 11

what are glycoproteins/glyoclipids?

Answer 11

chains of sugars attached to proteins or lipids

Question 12

where are glycoproteins/glycolipids located?

Answer 12

only on the outside of the cell

Question 13

what role to glycoproteins/glycolipids play?

Answer 13

they are very important for cell-cell recognition

Question 14

what is the defining factor for blood type?

Answer 14

the different glycoproteins attached to the outside of red blood cells (determines blood type)

Question 15

what determines the fluidity of the phospholipid membrane?

Answer 15

the number of unsaturated lipids in the phospholipd tails

Question 16

what are microdomains and how are they formed?

Answer 16

a collection of proteins and lipids that are floating within the membrane

Question 17

what can happen when two cells fuse?

Answer 17

the proteins in their membrane can mix

Question 18

which kind of molecules can cross the membrane unaided?

Answer 18

small hydrophobic molecules

and very small non-ionic molecules

Question 19

what kind of molecules require protein channels to cross the membrane?

Answer 19

most small hydrophilic molecules

Question 20

which molecules are unable to pass through the membrane?

Answer 20

larger molecules

Question 21

when does diffusion occur?

Answer 21

constantly and naturally to reach equilibrium

Question 22

which specialized transport mechanisms are needed for diffusion to occur?

Answer 22

none

Question 23

what is osmosis?

Answer 23

the diffusion of water

Question 24

what is required for osmosis to occur?

Answer 24

specific channels - aquaporins

Question 25

what is a hypertonic solution?

Answer 25

when water is lost from the cell through osmosis

Question 26

what is a hypotonic solution?

Answer 26

when water is gained from the cell though osmosis

Question 27

what is an isotonic solution?

Answer 27

when water is neither lost or gained from the cell via osmosis

Question 28

what disease is related to issues with osmosis in the body?

Answer 28

diabetes

Question 29

what are epithelial cells?

Answer 29

cells that line the outside of surfaces of tissues

Question 30

what sort of channels are aquaporins?

Answer 30

chanel proteins - always open

Question 31

what sort of proteins do Na+ and K+ ions travel through?

Answer 31

chanel proteins

Question 32

what are carrier proteins used to transport?

Answer 32

larger chemicals e.g. glucose or neurotransmitters

Question 33

do all carrier proteins carry all chemicals ?

Answer 33

no, all chemicals e.g. neurotransmitters have their own families of carrier proteins for transmission

Question 34

what are gated proteins?

Answer 34

channel proteins that can be controlled by voltage across the membrane or contact with a signalling molecule or chemical.

Question 35

what would cause short-term effects with gated proteins?

Answer 35

voltage across the membrane

contact with a signalling molecule

Question 36

what would cause a long-term effect with gated proteins?

Answer 36

chemical changes within the cell e.g. phosphorylation

Question 37

what is a uniporter?

Answer 37

a carrier protein that allows 1 thing across the channel from extracellular to intracellular

Question 38

what is a symporter?

Answer 38

where 2 molecules can quickly be passed across the membrane at the same time (in the same direction)

Question 39

what is an antiporter?

Answer 39

where two molecules can pass across the membrane, at the same time, in different directions

Question 40

what is a faster transporter - a symporter or an antiporter?

Answer 40

a symporter

Question 41

what example of transport requires energy ?

Answer 41

Na+ and K+ pump

Question 42

how are molecules transported across the membrane?

Answer 42

using energy from ATP

Question 43

what happens in a Na+ - K+ pump

Answer 43

3Na+ leave the cell and 2K+ come into the cell

Question 44

what is endocytosis?

Answer 44

where target materials bonded to the membrane are brought into the cell when the membrane invaginates to form a vesicle.

Question 45

what is exocytosis?

Answer 45

where vesicles meet the membrane and fuse, then release the contents from the cell e.g. neurotransmitters on synapses.