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M2C > 9/9/24 Membrane Structure and Composition > Flashcards

9/9/24 Membrane Structure and Composition Flashcards

1
Q

what membranes wrap the cell, separating it from the outside and dividing it into compartments?

A

lipid (=”oily”) membranes

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2
Q

how are liposomes prepared in the lab?

A

prepared in
the lab by assembling
synthetic lipids or breaking
cell membrane

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3
Q

what are vesicles?

A

naturally occurring cell
organelles with aqueous cavities

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4
Q

the cell envelope is a biological membrane made of __________
molecules

A

amphiphilic phospholipid

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5
Q

A biological membrane is an
enclosing or separating thin layer
of material that acts as a ________________________________________________________________

A

selectively permeable barrier

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6
Q

describe the thin lipid layer that is trapped by the biological membrane

A

not
permeable to many small
compounds and large molecules

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7
Q

the phospholipid monolayer consists of what liquid

A

oil

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8
Q

the phospholipid bilayer

A

water

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9
Q

what are examples of small molecules that diffuse across lipid bilayer:

A

Co2, 02, H20

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10
Q

what are molecules that the lipid bilayer cannot diffuse across ?

A

Ions, and larger uncharged molecules such as glucose,
can not diffuse across.

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11
Q

what are the characteristics of the amphiphilic molecules in the phospholipid double layer

A

they have hydrophilic and hydrophilic sides

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12
Q

what are the role of proteins in the membrane?

A

control its permeability to
different compounds, sense the outside, and trigger intracellular
response signals.

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13
Q

what are the roles of sterols in the membrane?

A

control membrane properties

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14
Q

True or False: Lipids are the only components of the membrane.

A

False. Lipids are not the only components of the membrane.

other components include:
-proteins & sterols
-carbohydrates

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15
Q

what roles do lipids play in the membrane?

A

-compartmentalization
- metabolic energy conversion via oxidation
- control of metabolic processes (steroid hormones & prostaglandins)

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16
Q

What does the consistency of the membrane depends on?

A

composition and temperature

ex: when membrane undergoes heat it transforms from a gel-like consistency to a fluidlike consistency

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17
Q

define micelle

A

cone-shaped amphiphilic molecules forming curve structures

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18
Q

define bilayer

A

Cylinder-shaped amphiphilic molecule

ex: phospholipids

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19
Q

Bilayer thickness & curvature are affected by what?

A

Liquid composition

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20
Q

what are the building blocks of lipids?

A

fatty acids

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21
Q

what structural lipid is primarily found in membranes?

A

sterols

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22
Q

what are the simplest lipids ?

A

fatty acids

23
Q

describe a hydrocarbon long hydrocarbon chain

A

16-18 carbons ending with a carboxyl group

24
Q

the saturated chain adopts ________ conformations

A

extended

25
Q

unsaturated fatty acids have one or more _______________

A

double bonds

26
Q

double bonds in natural
unsaturated fatty acids
introduce

A

a kink

27
Q

double bonds in natural
unsaturated fatty acids are commonly in what configuration

A

cis config

28
Q

what is an essential polyunsaturated fatty acid (PUFA) needed in the diet for synthesis of critical signaling molecules like Arachidonic Acid

A

Omega-3

29
Q

the extent of packing depends on the degree of _________

A

saturation

30
Q

the longer the chain…..

A

the more organized
the less fluid

31
Q

the more (cis) double bonds…..

A

the more disorganized
the more fluid

32
Q

how do trans fatty acids form

A

by partial
breakdown of unsaturated fatty
acids (usually industrial)

33
Q

a trans double bond allows a
given fatty acid to adopt what

A

extended conformation

34
Q

trans fatty acids can pack

A

more regularly, show higher
melting points than cis forms

35
Q

trans fatty acids have

A

higher melting points than cis forms

36
Q

True or False: trans unsaturated fatty acids raise your “good” cholesterol

A

it raises your “bad” cholesterol

37
Q

which double bond forms a kink

A

cis double bond

38
Q

how can fatty acids be linked through Glycerol

A

triacyclglycerols (TAG)

39
Q

what does TAG consist of

A

glycerol + 3 fatty acids

40
Q

what form are majority of the fatty acids found in

A

TAGs

41
Q

what are solid TAGs called?

A

fats

42
Q

what are liquid TAGs called?

A

oils

43
Q

what are the primary storage forms of lipids (body fat)?

A

TAGs

44
Q

where do TAGs exist?

A

in the cytoplasm as droplets/deposits

45
Q

why are TAGs less soluble in water than fatty acids?

A

lack of charge carboxylate group

46
Q

Mixtures of TAGs differ in their _____________

A

fatty acid composition

47
Q

fatty acid composition of which three food fats?

A

olive oil, butter, and beef fat

48
Q

Why do fats and oils float?

A

because TAGs are less dense than water

49
Q

How are cell membrane lipids formed?

A

fatty acids combine through scaffold to a head group

50
Q

What are Glycerol and Sphingosine used by?

A

the scaffold to connect 1-2 hydrophobic fatty acids + polar head group

51
Q

True or False: in the phospholipid bilayer the head is hydrophilic.

A

True. Hydrophilic head

52
Q

True or False: in the phospholipid bilayer the tail is hydrophobic

A

True. hydrophobic tail

53
Q
A

M2C (11 decks)

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