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PHYSL 212 > CELL 1 > Flashcards

CELL 1 Flashcards

1
Q

what does PM of cell look like in electron micrograph

A

3 layers

  • 2 dark layers
  • 1 light layer
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2
Q

what molecules make up PM

A
  • lipid molecules

- proteins

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3
Q

what does 1st dark line correspond to

A

polar regions of lipids and proteins

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4
Q

what does middle light layer correspond to

A

non polar regions of lipids and proteins

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5
Q

what does 2nd dark line correspond to

A

polar regions of lipids and proteins

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6
Q

what is a polar molecule

A

molecule in which distribution of electrons across covalent bond unequal

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7
Q

what does unequal distribution of electrons result in

A
  • pos end

- neg end

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8
Q

what is a non polar molecule

A

molecule in which distribution of electrons across covalent bond equal

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9
Q

what is major lipid molecule in PM

A

phospholipid

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10
Q

what are components of phospholipid

A
  • polar / hydrophilic head

- non polar / hydrophobic tail

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11
Q

why is phospholipid amphipathic

A

has hydrophilic + hydrophobic region

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12
Q

what is attached to glycerol backbone

A
  • polar phosphate group

- 2 non-polar fatty acid chains

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13
Q

how do phospholipids spontaneously arrange themselves in aqueous enviro

A
  • polar head groups interact w water

- non polar tails face away from water

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14
Q

what is conformation of phospholipids (2)

A
  • energetically stabilizing

- favourable

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15
Q

what does layer of hydrophobic tails form

A

hydrophobic core

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16
Q

what makes lipid molecules that form micells diff from phospholipids

A

1 HC tail instead of 2

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17
Q

why can’t phospholipids form micells

A

2 HC tails too bulky to fit in centre

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18
Q

what do fatty acid chains contain

A
  1. HC chain

2. carboxylic acid

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19
Q

what do double bonds in fatty acid chains do

A

put kinks in HC chain

20
Q

what is result of kinks in fatty acid chains

A

unable to pack as closely together

21
Q

what is cholesterol

A

lipid molecule found in PM

22
Q

what are 3 components of cholesterol

A
  1. steroid ring
  2. hydroxyl group
  3. HC side chain
23
Q

why is cholesterol amphipathic

A
  • HC chain makes it hydrophobic

- OH makes it hydrophilic

24
Q

how are mem lipids arranged

A

asymmetrically

25
Q

what does fluid mosaic model state

A
  • structure of mem dynamic

- globular proteins float in sea of phospholipids

26
Q

what do carbohydrates attach to in mem (2)

A
  1. proteins

2. lipids

27
Q

what does lipid bilayer give to mem (2)

A
  1. fluidity

2. elasticity

28
Q

what type of proteins does FMM consider (2)

A
  1. peripheral mem proteins

2. integral mem proteins

29
Q

how are integral mem proteins stuck into mem

A

a. partially

b. completely span bilayer

30
Q

where do peripheral mem proteins lie

A

above plane of mem

31
Q

what do peripheral mem protiens attach to

A
  1. proteins

2. lipids

32
Q

what 2 ideas does FMM focus on

A
  1. mem is fluid

2. mem is mosaic

33
Q

why is PM described as fluid

A

hydrophobic integral components (lipids + proteins) move laterally

34
Q

what can limit movement of lipids + proteins

A

attached to other components

a. in mem
b. inside cell
c. outside cell

35
Q

how do lipids and proteins move

A

rotate about long axis

36
Q

how do lipids move

A
  • flex HC tails
37
Q

when is rate of phospholipid movement higher

A
  • shorter HC chains ==> less interaction bw adjacent tails

- double bonds bw carbons. ==> phospholipids cannot pack as closely together

38
Q

what influences fluidity

A
  1. saturation of fatty acids
  2. temp
  3. cholesterol content
39
Q

when is mem more fluid

A
  1. unsaturated fatty acids
  2. high temp
  3. less cholesterol
40
Q

when is mem less fluid

A
  1. saturated fatty acids
  2. low temp
  3. more cholesterol
41
Q

what is cholesterol able to prevent at low temps

A

crystallization of fatty acids

42
Q

what is cholesterol able to prevent at high temps

A

movement of phospholipids

43
Q

what does fluidity of mem lead to

A

asymmetry bw outer and inner layers

44
Q

what does assymetry support

A

diff fxns of outer and inner layer

45
Q

what are examples of asymmetry

A
  1. outer and inner surfaces have diff proteins
  2. carbs only in outer surfaces
  3. outer and inner surfaces have diff phospholipid compositions
46
Q

what would happen without mem fluidity

A
  1. mem proteins would stop functioning

PHYSL 212 (22 decks)

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