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Biol 331 > Polvi lec #2 > Flashcards

Polvi lec #2 Flashcards

1
Q

Can you visualize cell membranes using a light microscope? why or why not?

A

No, because the cell membrane is too small (5-10nm wide).

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2
Q

When were plasma membranes first observed? Using what?

A

They were first observed in the 1950s using an electron microscope

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3
Q

What are membranes composed of? How was this discovered?

A

lipids, Overton found this by dipping the plant root hairs into solution and found that they more readily took up nonpolar solutes

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4
Q

Membranes have how many layers? How was this found?

A

Membranes have two layers (bilayer) and this was found by Gorter and Grendel in 1925 which showed that lipids from a red blood cell could cover the cell twice.

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5
Q

Why did Gorter and Grendel use a red blood cell in their experiment?

A

Because they didn’t have any interior membranes, only one

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6
Q

What two things do membranes have?

A

lipids and proteins

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7
Q

What this the membrane bilayer composed of?

A

Phospholipids

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8
Q

Where do polar phosphatesbl face?

A

the membrane surface (where aqueous stuff is)

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9
Q

Where do nonpolar fatty acid tails face?

A

Into the interior of the membrane (so they don’t interact w polar water)

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10
Q

What does the lipid bilayer prevent?

A

Prevents random movement of substances in and out of the cell

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11
Q

What is the structure of fatty acids?

A

They are long unbranched hydrocarbon chains, have typically 14-20 carbons, can saturated or unsaturated

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12
Q

What are saturated fatty acids?

A

Lack double bonds

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13
Q

What are unsaturated fatty acids?

A

Has one or more double bonds
introduces a bending in the fatty acid

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14
Q

What kind of double bonds do naturally occurring fatty acids have?

A

cis

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15
Q

What do unsaturated fatty acids do to phosolipids packing?

A

The bend stops phospholipids from packing tightly

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16
Q

What are membrane lipids?

A

are lipids that make up the membrane

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17
Q

What are the three kinds of membrane lipids?

A

Phosphoglycerides
Sphingolipids
Cholesterol

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18
Q

Are all phosphoglycerides phospholipids?

A

yes

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19
Q

Are all sphingolipids phospholipids?

A

no only some

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20
Q

Most membrane phospholipids are what?

A

phosphoglycerides

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21
Q

What are the components of phosphoglycerides?

A

glycerol back bone, two fatty acid chains, a phosphate group, and an additonal group

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22
Q

What types of fatty acid chains do phosphoglycerides commonly have?

A

One unsaturated and one saturated fatty acid chain

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23
Q

What are the 5 different types of phosphoglycerides? What are they differentiated by?

A

Phosphatic acid
Phosphatidylcholine
Phosphatidylserine
Phosphatidyl-ethanolamine
Phosphatidylinositol
They are differentiated by their head groups

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24
Q

What the overall charge of phosphatidic acid?

A

Additional group is H, so negatively charged

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25
Q

What is the overall charge of phosphatidylcholine?

A

Has a choline additional group, is neutral

26
Q

What is the overall charge of phosphatidylserine?

A

Has a serine additional group, is negatively charged

27
Q

What is the overall charge of phosphatidyl-ethanolamine?

A

Has a ethanolamine additional group, is neutral

28
Q

What is the overall charge of Phosphatidylinositol?

A

Has an inositol additional group, is negatively charged

29
Q

What is a polar head group?

A

P group plus additional group

30
Q

Are sphingolipids less or more abundant in membranes?

A

less

31
Q

What is the structure of sphingolipids?

A

Built on a sphingosine spine, so has a polar head group and hydrophobic tail, the sphingosine is attached to a fatty acid, the polar head group can also attach to additional groups

32
Q

What is the most basic example of a sphingolipid?

A

ceramide, made of just sphingosine and fatty acid

33
Q

Sphingolipids are hydrophobic or hydrophillic?

A

Neither, they are amphipathic

34
Q

What is sphingomyelin?

A

is a sphingolipid with a phosphorylcholine group attached, this makes it also a phospholipid

35
Q

What has more longer and saturated fatty acid tails, sphingolipids or phosphoglycerides?

A

sphingolipids

36
Q

What are the roles of sphingolipids?

A

signal transduction, membrane structure, and sensing

37
Q

If the additional group to a sphingolipid is a carbohydrate. what is the molecule called?

A

A glycosphingolipid (in short a glycolipid)

38
Q

What two types of glycolipids are there?

A

cerebrosides and gangliosides

39
Q

What is a cerebroside?

A

a glycolipid where the carbohydrate additional group is a simple sugar (for ex galactose)

40
Q

What is a ganglioside?

A

a glycolipid where the carbohydrate addition is a clusters of sugars that includes sialic acid

41
Q

Membranes in the nervous system have a lot of what?

A

glycosphingolipids

42
Q

What can alterations in glycolipid abundance result in?

A

neurological diseases

43
Q

What is tay sachs disease? How does it connect to the neurological diseases we see when glycolipid abundance gets altered?

A

Is a deficiency of an enzyme that normally breaks down GM2 ganglioside, this causes excess GM2 buildup and impairs the function of nerve cells

44
Q

Is cholesterol flexible? Why or why not?

A

No, because it has large carbon chains

45
Q

How much of the plasma membrane lipid sin animal cells does cholesterol make?

A

50%

46
Q

What is cholesterols structure?

A

Has a polar head group, and big carbon chains

47
Q

Where is cholesterol oriented in the membrane?

A

oriented with small hydrophilic groups which face the membranes surface, rest of it is the fatty acid tails of phospholipids

48
Q

What do cholesterols do the movement of fatty acid tails in phosphlipids?

A

slow it down cause it’s big and bulky

49
Q

Are the lipids found on the two layers of membrane the same?

A

No, ratios of exoplasmic (facing outside) and cytosolic (facing inside) vary of each lipid

50
Q

Which lipids are more exoplasmic?

A

sphingomyelin, phosphatidylcholine

51
Q

Which lipids are more cytosolic?

A

phosphatidylserine
phosphatidylethanolamine
phosphatidylinositol

52
Q

What lipids are equals parts cytosolic and exoplasmic?

A

cholesterol

53
Q

What does membrane lipid asymmetry affect? give examples?

A

Asymmetry affects membrane permeability, surface charge, membrane shape, and stability
Phosphatidylethanolamine- promotes curvature of membrane
phosphatidylserine- has a negative charge which interacts with transmembrane proteins
Phosphatidylinositol- has roles in signal transduction

54
Q

10% of membrane carbs are covalently linked to what?

A

lipids

55
Q

50% of membrane carbs of covalently linked to what?

A

proteins

56
Q

All membrane carbohydrates face what in the membrane?

A

the extracellular space, only outerleaflet has them

57
Q

Do carbohydrates vary in diff cell types and tissues?

A

yes

58
Q

What role do carbohydrates play, given an example?

A

play important roles as receptors, sorting membrane proteins, and cell recognition, theyre the ones that recognize blood type antigens

59
Q

What can lipid composition determine?

A

the state of the membrane, it can help with protein interactions, and has role sin signal transduction

60
Q

What is myeline sheath composed of?

A

multiple layers of plasma membrane with very little protein

61
Q
A

Biol 331 (31 decks)

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