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IMS > Structure and Function of Plasma membrane > Flashcards

Structure and Function of Plasma membrane Flashcards

1
Q

What are the 4 Major components of a Eukaryotic Cell?

A

Plasma Membrane
Nucleus
Membrane-Bound organell
Cytoskeleton

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2
Q

What does the Plasma membrane do?

A

Defines boundaries of the cell

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3
Q

Why must the Plasma membrane physically seperate the interior of cell from surrounding enviroment?

A

For regulation and to keep desirable substances in the cell

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4
Q

What are the 6 functions of The Plasma Membrane?

A 
Barrier - entry/exit of substances
Site Metabolic Activities - mitochondria
Ion transport - nerve impulses
Cell signalling - communication
Cell shape - eg erythrocytes
Cell-Cell interaction - adhesion molecules
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5
Q

What are the 3 identities of the Existence of Plasma membrane?

A

1) Cell swelling (hypotonic less concentrated) & Shrinking (hypertonic more concentrated)
2) Escape of Cell contents (if ruptured)
3) Compartments (most internal organelles, chemical activities)

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6
Q

Who and When discovered the PM?

A

Robertson in 60’s - Unit membrane

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7
Q

Who and What model discovered in the 70’s?

A

Singer and Nicholson - Fluid Mosaic Model

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8
Q

How was the Unit membrane found by Robertson?

A

Used Osmium to stane the membrane and found railroad track structure

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9
Q

Describe Robertsons Railroad track structure?

A

Trilaminer consisting of 2 Dark lines (outer inner layer) containing polar head group
Seperated by Central Light space containing hydrophobic tail of lipid molecules

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10
Q

What did Electron Microscopy studies find?

A

Cells are seperated by thin PM that retains cell contents

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11
Q

What does Fluid Mosaic Model consist of?

A

2 Fluid layers of lipid and Proteins within or on Lipids

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12
Q

Describe the Structure of the Plasma Membrane?

A

Lipid molecules 50% of mass, Asymmetrically distributed, Amphiphilic with hydrophilic head and hydrophobic tail

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13
Q

What are the 3 Common types of Membrane Lipid Fluids?

A

Phospholipids
Glycolipids
Sterols

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14
Q

Describe Structure of Phospholipids?

A

2 Hydrocarbon tails - fatty acids
Tails differ in length between 14-24 carbon
Cis-double bonds in 1 tail creating Kink

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15
Q

Why do Phospholipid Molecules Aggregate?

A

Keep Hydrophobic tails in the interior and Expose Hydrophilic heads to water

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16
Q

What are the 2 types of Aggregation styles?

A

Cone shaped

Cylinder shaped

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17
Q

Describe Cone shaped aggregation?

A

Lipid molecules in a single chain form micelles

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18
Q

Describe Cylinder shaped aggregation?

A

Phospholipid molecules (double tailed) form bilayer

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19
Q

What is a Glycerol Based Phospholipid called?

A

Phosphoglyceride

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20
Q

What are the 4 Main types of Phosphoglycerides in PM?

A

Phosphatidylcholine
Phosphatidylethanolamine
Phosphatidylserine (-)
Phosphatidylinositol

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21
Q

Why is Phosphatidylserine Negative?

A

Activates certain enzymes with negative charge during apoptosis so PM modify and express on outer of membrane so macrophages recognize and remove out of system

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22
Q

What is the Main type of Sphingolipid in PM?

A

Spingomyelin

23
Q

Describe the Phospholipid structure?

A

Polar head (such as choline, ethanolamine, serine, inositol)
Lipid backbone
Glycerol or Spinogosine based

24
Q

How are Glycolipids formed?

A

By the Addition of a CHO group to lipids

25
Q

What is a Glycerol based glycolipid called?

A

Glycolipid

26
Q

What is a Spingosine based glycolipid called?

A

Spingolipid

27
Q

What is a combination of glycerol and sphinogosine based glycolipids called?

A

Glycosphingolipids

28
Q

What are the 2 most Common Glycosphingolipids?

A

Cerebrosides

Gangliosides

29
Q

Describe Function of Cerebrosides?

A

Act as Antigens

30
Q

Describe Function of Gangliosides?

A

Determine ABO blood group system

31
Q

Where are cerebrosides and gangliosides more prominent?

A

Nervous System

32
Q

Describe Glycolipid Structure?

A

Carbohydrate head group
Lipid backbone
Glycerol or sphingobased

33
Q

What do Sterols in the Eukaroytic PM store large amounts of?

A

Cholesterol

34
Q

What does Sterols affect?

A

PM Fluidity, increases permeability barrier properties

35
Q

What does Sterols Maintain?

A

Stability and Integrity of PM

36
Q

What does the Lipid Bilayer depend on?

A

Composition (type of phospholipid)

and Temperature

37
Q

Describe the Composition of the Lipid Bilayer?

A
  • Shorter chain lengths (reduces tails interaction with opposition monolayer)
  • Cis double bonds (produce kinks in hydrocarbon chains, make difficult to pack together)
38
Q

Describe Temperature of Lipid Bilayer?

A

The movement decrease when the temperature drops and Increases as it rises

39
Q

What kind of Movements are they of Phospholipid molecules in the membrane?

A
  • Rotation its long axis
  • Lateral diffusion by exchanging places with neighbouring molecules in same layer
  • Transverse diffusion or flipflop to opposite layer
40
Q

What are the 3 Capable kinds of movements of Phospholipid molecules in the Membrane?

A

Flexion
Rotation
Lateral Diffusion

41
Q

What are the classes of Proteins?

A

Integral
Peripheral
Lipid Anchored

42
Q

Where are Integral proteins?

A

Embedding within bilayer

43
Q

What are the Regions within Integral Proteins?

A

Hydrophobic segments have affinity for interior, Hydrophilic regions extend outwards to aqeous phase

44
Q

Where are Peripheral Proteins located?

A

Surface of PM linked to polar head of phospholipids, more hydrophilic lack hydrophobic segment

45
Q

Where are Lipid Anchored Proteins?

A

Attached to lipid molecules in bilayer, hydrophilic on surface of membrane

46
Q

What are Lipid Rafts?

A

Transient clusters of lipids and proteins within membrane

47
Q

What do Lipid Rafts do?

A

Increase function efficiency - existence is controversial

48
Q

What are the Functions of the Plasma Membrane?

A

Barrier and Transport and Signal detection

49
Q

Describe the Barrier function of PM?

A

Allow nutrients to enter and keep out harmful
Defines boundaries of cell and compartments
Seperates organelles into discrete regions

50
Q

Describe the Transport function of PM?

A

Controls the passage of substances in/out of cells, selective permeable, proteins in bilayer act as pore channels

51
Q

What are the Main transport Proteins of the PM?

A

Transporter proteins

Ion Channel proteins

52
Q

Describe Signal detection of the PM?

A

Cells receive info from enviroments via signals, chemical signals bind to specific receptor proteins

53
Q

What does a Signal and Receptor create?

A

Molecular event inside

54
Q

Give an example of protein for Liver and Muscle PM?

A

Insulin - insulin binds to liver and muscle cells to facilitate uptake of glucose

IMS (53 decks)

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