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Cell Bio > Exam 4 (Topic 17) > Flashcards

Exam 4 (Topic 17) Flashcards

1
Q

The plasma membrane is

A

A selective barrier

Fluid

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2
Q

A selective barrier

A

Plasma Membrane

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3
Q

In eucaryotes, the plasma membrane

A

Separates the contents of organelles

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4
Q

Three important functions of cell membranes

A
  1. Communicate with the outside environment
  2. Allow waste material to exit the cell and nutrients to enter the cell
  3. Allow expansion and movement of the cell
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5
Q

The plasma membrane can be deformed without

A

Tearing (Usually)

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6
Q

If the plasma membrane is pierced

A

it quickly reseals

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7
Q

When an area of the plasm membrane is enlarged, it

A

adds more membrane

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8
Q

The plasma membrane of cells is composed of

A

Lipids AND Proteins

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9
Q

Lipid bilayer

A

two opposing layers of lipids (proteins associate with

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10
Q

Long hydrocarbon chain (hydrophobic) and Carboxyl group (hydrophili)

A

Fatty Acids

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11
Q

Fatty acids are

A

amphipathic

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12
Q

The hydrocarbon tail has no double bonds

A

Saturated Fatty Acid

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13
Q

C=C double bonds create a kink in the fatty acid tail

A

Unsaturated Fatty Acids

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14
Q

Fatty Acid saturation is in the ______ formation

A

Cis

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15
Q

What provides the kink in the FA tail

A

Cis-double bonds

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16
Q

Fatty Acids are linked together by

A

Ester Linkages

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17
Q

FAs linked to glycerol molecule

A

Triacylglycerols

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18
Q

Major component of cell membranes

A

Phospholipids

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19
Q

Triacylglycerol but with a phosphate and hydrophilic group attached to a carbon instead of a fatty acid

A

Phospholipids

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20
Q

Most common phospholipid in cell membranes

A

Phoshatidylcholine

Small molecule choline (charged molecule) added to the phosphate

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21
Q

Small molecule choline (charged molecule) added to the phosphate

A

Phoshatidylcholine

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22
Q

All membrane lipids are

A

amphipathic

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23
Q

Lipids with sugar group instead of phosphate group

A

Glycolipid

24
Q

Because of the amphipathic nature of phospholipids, the lipid bilayer is the

A

most stable arrangement of lipids

25
Q

Why does the lipid bilayer sheet fold into a sphere?

A

Because it can’t have any edges exposed to water

26
Q

Pure phospholipids in water form a spherical bilayer called

A

A Liposome

27
Q

The water outside and inside the cells prevent the phospholipids from

A

Coming out of the lipid bilayer

But that doesn’t prevent movements within the lipid bilayer

28
Q

Four possible SPONTANEOUS movements of phospholipids

A
  1. Flexing
  2. Lateral Diffusion
  3. Rotation
  4. Flip-flop (very rare)
29
Q

The fatty acid tails are somewhat bendable

30
Q

The phospholipids within one monolayer of the lipid bilayer can move around

A

Later diffusion

31
Q

The phospholipid itself can spin in a circle

32
Q

The phospholipid can move from one monolayer to the other

A

Flip-flop (RARE- about once a month)

33
Q

How fluid a membrane is depends on

A
  1. Phospholipid Composition
  2. Length of hydrocarbon tails
  3. Degree of saturation
34
Q

Phospholipid composition

A

Contain different polar heads and have different properties

35
Q

Most phospholipids have a hydrocarbon tail length of

A

14-24 carbons (18-20 most common)

36
Q

A shorter hydrocarbon chain reduces

A

Hydrophobic interactions causing the membrane to be more fluid

37
Q

Unsaturated is

A

more fluid

38
Q

Hydrogenated oil is a process that

A

saturates the oil and make it more solid

39
Q

Liquid at room temps

A

Unsaturated lipids

40
Q

In animal cells membrane fluidity is adjusted by

A

the addition of cholesterol

41
Q

Polar head group (-OH) and rigid non-polar ring structure

A

Cholesterol

42
Q

Makes up roughly 20% of the weight of plasma membranes

A

Cholesterol

43
Q

Fill spaces between phospholipids and stiffens the bilayer

A

Cholesterol

44
Q

Less Fluid to More Fluid

A

Saturated, 1/3 Unsat 1/3 sat 1/3 cholesterol, 1/2 sat and 1/2 unsat

45
Q

The lipid bilayer is

A

asymmetrical

46
Q

The lipid bilayer contains

A

Cytosolic leaflet and Non-cytosolic leaflet

47
Q

New phospholipids are made and added to the

A

Cytoplasmic leaflet of the lipid layer on the ER

48
Q

________ selectively transfer specific types of lipids to the non-cytoplasmic leaflet

A

Flippases

maintains asymmetry and allows membrane to grow evenly

49
Q

ER membrane that contains newly made lipid bilayer pinches off in vesicles and

A

Fuses with other organelles and the plasma membrane

50
Q

All animal cells are coated with

A

Sugars (glycolipids and glycoproteins)

51
Q

Glycolipids are only found in

A

The non-cytoplasmic leaflet of lipid bilayers

52
Q

Some lipids are synthesized in the

A

Smooth ER lumen and placed in the non-cytoplasmic leaflet

53
Q

Vesicles pinch off from the ER and fuse with the golgi where the lipids acquire

A

Sugar molecules

54
Q

Vesicles pinch off from the Golgi and

A

Fuse with the plasma membrane

55
Q

Glycolipids on the non-cytoplasmic leaflet of the organelles and vesicles now face

A

The extracellular environment

56
Q

Two mechanisms to maintain asymmetry in the lipid bilayer

A

Flippases

Addition of lipids from the lumen of the organelle

Cell Bio (30 decks)

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