CELL 1

Question 1

what does PM of cell look like in electron micrograph

Answer 1

3 layers

• 2 dark layers
• 1 light layer

Question 2

what molecules make up PM

Answer 2

• lipid molecules

- proteins

Question 3

what does 1st dark line correspond to

Answer 3

polar regions of lipids and proteins

Question 4

what does middle light layer correspond to

Answer 4

non polar regions of lipids and proteins

Question 5

what does 2nd dark line correspond to

Answer 5

polar regions of lipids and proteins

Question 6

what is a polar molecule

Answer 6

molecule in which distribution of electrons across covalent bond unequal

Question 7

what does unequal distribution of electrons result in

Answer 7

• pos end

- neg end

Question 8

what is a non polar molecule

Answer 8

molecule in which distribution of electrons across covalent bond equal

Question 9

what is major lipid molecule in PM

Answer 9

phospholipid

Question 10

what are components of phospholipid

Answer 10

• polar / hydrophilic head

- non polar / hydrophobic tail

Question 11

why is phospholipid amphipathic

Answer 11

has hydrophilic + hydrophobic region

Question 12

what is attached to glycerol backbone

Answer 12

• polar phosphate group

- 2 non-polar fatty acid chains

Question 13

how do phospholipids spontaneously arrange themselves in aqueous enviro

Answer 13

• polar head groups interact w water

- non polar tails face away from water

Question 14

what is conformation of phospholipids (2)

Answer 14

• energetically stabilizing

- favourable

Question 15

what does layer of hydrophobic tails form

Answer 15

hydrophobic core

Question 16

what makes lipid molecules that form micells diff from phospholipids

Answer 16

1 HC tail instead of 2

Question 17

why can’t phospholipids form micells

Answer 17

2 HC tails too bulky to fit in centre

Question 18

what do fatty acid chains contain

Answer 18

1. HC chain

2. carboxylic acid

Question 19

what do double bonds in fatty acid chains do

Answer 19

put kinks in HC chain

Question 20

what is result of kinks in fatty acid chains

Answer 20

unable to pack as closely together

Question 21

what is cholesterol

Answer 21

lipid molecule found in PM

Question 22

what are 3 components of cholesterol

Answer 22

1. steroid ring
2. hydroxyl group
3. HC side chain

Question 23

why is cholesterol amphipathic

Answer 23

• HC chain makes it hydrophobic

- OH makes it hydrophilic

Question 24

how are mem lipids arranged

Answer 24

asymmetrically

Question 25

what does fluid mosaic model state

Answer 25

- structure of mem dynamic | - globular proteins float in sea of phospholipids

Question 26

what do carbohydrates attach to in mem (2)

Answer 26

1. proteins | 2. lipids

Question 27

what does lipid bilayer give to mem (2)

Answer 27

1. fluidity | 2. elasticity

Question 28

what type of proteins does FMM consider (2)

Answer 28

1. peripheral mem proteins | 2. integral mem proteins

Question 29

how are integral mem proteins stuck into mem

Answer 29

a. partially | b. completely span bilayer

Question 30

where do peripheral mem proteins lie

Answer 30

above plane of mem

Question 31

what do peripheral mem protiens attach to

Answer 31

1. proteins | 2. lipids

Question 32

what 2 ideas does FMM focus on

Answer 32

1. mem is fluid | 2. mem is mosaic

Question 33

why is PM described as fluid

Answer 33

hydrophobic integral components (lipids + proteins) move laterally

Question 34

what can limit movement of lipids + proteins

Answer 34

attached to other components a. in mem b. inside cell c. outside cell

Question 35

how do lipids and proteins move

Answer 35

rotate about long axis

Question 36

how do lipids move

Answer 36

- flex HC tails

Question 37

when is rate of phospholipid movement higher

Answer 37

- shorter HC chains ==> less interaction bw adjacent tails | - double bonds bw carbons. ==> phospholipids cannot pack as closely together

Question 38

what influences fluidity

Answer 38

1. saturation of fatty acids 2. temp 3. cholesterol content

Question 39

when is mem more fluid

Answer 39

1. unsaturated fatty acids 2. high temp 3. less cholesterol

Question 40

when is mem less fluid

Answer 40

1. saturated fatty acids 2. low temp 3. more cholesterol

Question 41

what is cholesterol able to prevent at low temps

Answer 41

crystallization of fatty acids

Question 42

what is cholesterol able to prevent at high temps

Answer 42

movement of phospholipids

Question 43

what does fluidity of mem lead to

Answer 43

asymmetry bw outer and inner layers

Question 44

what does assymetry support

Answer 44

diff fxns of outer and inner layer

Question 45

what are examples of asymmetry

Answer 45

1. outer and inner surfaces have diff proteins 2. carbs only in outer surfaces 3. outer and inner surfaces have diff phospholipid compositions

Question 46

what would happen without mem fluidity

Answer 46

1. mem proteins would stop functioning