Membrane Structure Flashcards

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1
Q

_________ is a barrier to prevent the contents of cells from escaping & mixing with molecules in the surrounding environment & it also allows nutrients to come in & waste to leave

A

The plasma membrane

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2
Q

_________ is responsible for the structure of all cell membranes

A

Lipid bilayer

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3
Q

__________ form bilayer in water

A

Membrane lipids

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4
Q

The types of lipids found in cell membranes are _____________

A

Phospholipids

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5
Q

Phospholipids

A

Have a phosphate - containing hydrophillic head linked to a pair of hydrophobic hydrocarbon tails

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6
Q

Amphipathic

A

Molecules with both hydrophillic & hydrophobic parts

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7
Q

Phospolipids are __________

A

Amphipathic

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8
Q

What are the two conflicts that happens with amphipathic molecules?

A
  1. The hydrphillic head is attracted to water
  2. The hydrophobic tail shun water
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9
Q

A ________ fixes the conflict in amphipathic molecules where in a ________ the hydrophilic head faces water & the hydrophobic tails are shield from water

A

Bilayer

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10
Q

When a _________ is form the ________ is quickly fixed (They are self - sealing the amphipathic molecules)

A

Free edge (tear in the bilayer)

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11
Q

The lipid bilayer is a ___________

A

Flexible 2-D fluid

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12
Q

____________ spontaneously close in on themselves to form sealed compartments called lipidosomes

A

Phospholipids bilayers

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13
Q

The _______ of a lipid bilayer depends on its composition

A

Fluidity

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14
Q

The fluidity of a cell membrane

A

Is the ease that the lipid molecules move within the bilayer

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15
Q

How _______ a lipid is depends on its phospholipid composition mostly on how packed the hydrocarbon tails are

A

Fluid

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16
Q

The closer & more packed the hydrocarbon tails the __________ the bilayer is

A

Less fluid

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17
Q

What are the two major properties that affect how tightly hydrocarbons will pack?

A
  1. Their length
  2. The number of double bonds they contain
18
Q

The ________ the hydrocarbon tails are they are less likely to interact with one another which increases the fluidity of the bilayer

A

Shorter

19
Q

_____________ can form closed, spherical liposomes

A

Pure Phospholipids

20
Q

A hydrocarbon tail that contains a __________ is unsaturated

A

A double bond

21
Q

A hydrocarbon tail that contain _________ is saturated

A

Single Bonds

22
Q

Lipids bilayers that contain large amount of _________ are more fluid than those with small amounts

A

Double bonds

23
Q

_________ stiffens cell membranes & prevents light packing of phospholipids

A

Cholesterol

24
Q

Membrane assembly begin in the __________

A

ER (Endoplasmic retriculum)

25
Q

In ___________ phospholipids are formed in the ER (The cytosolic surface)

A

Eukaryotic cells

26
Q

Phospholipids make it to the otherside of the layer by enzymes called __________

A

Scramblase

27
Q

Scramblase

A

Transporter protein that moves randomly selected phospholipids from outer to the inner membrane at the side time moving an inner to the outer membrane

28
Q

The ________ membrane contains flippases

A

Gogi membrane

29
Q

Flippases (Flip Flop movement)

A

Moves specific phospholipids from the outer side into the inner side of the membrane

30
Q

__________ helps establish & maintain the asymmetric distribution of the phospholipids characteristic of animal cell membranes

A

Flippases

31
Q

_________ have a variety of functions

A

Plasma membrane proteins

32
Q

______________ associate with the lipid bilayer in different ways

A

Membrane proteins

33
Q

A ___________ chain usually crosses the lipid bilayer as an alpha helix

A

Polypeptide

34
Q

__________ are alpha helix because the hydrocarbon side chains are exposed on the outside of the helix where they contact the hydrophobic lipids tails

A

Polypeptides

35
Q

Integral membrane proteins

A

Are permanently bound

36
Q

Peripheral membrane proteins

A

Are temporarily bound

37
Q

Transmembrane proteins

A

Type of integral membrane proteins & external through the lipid bilayer

38
Q

___________ bound to other membrane proteins

A

Peripheral membrane

39
Q

The backbone of a polypetide chain is _____________

A

Hydrophilic

40
Q

A ____________ polypeptide chain usually crosses the lipid bilayer as an alpha helix

A

Transmembrane

41
Q

The __________ is reinforced by the underlaying cell cortex

A

Plasma Membrane

42
Q

What are some roles of membrane proteins?

A
  1. Some transport substances across the lipid bilayer
  2. Some anchor the membrane to molecules on the outside and inside of the cell
  3. Some detect chemical signals on the outside and relay them into the cell’s interior
  4. Some act as enzymes to carry out a reaction near the membrane.