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FLC > Membrane Structure & Synthesis > Flashcards

Membrane Structure & Synthesis Flashcards

1
Q

How many membranes are there in the body?

A

Multiple different types of biological membranes with varying compositions and functions

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2
Q

Which part of the phospholipid is hydrophobic?

A

The tails - composed of the fatty acid chains

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3
Q

What significant structure do phospholipids form?

A

lipid Bi layers (membranes)

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4
Q

What causes the asymmetry of membranes?

A

The outside of the cell has a different composition to the inside

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5
Q

What are the different components of a lipid molecule?

A
  • Polar head
  • Choline, serine, ethanolamine, inositol
  • Phosphate
  • Glycerol
  • Fatty acid chains
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6
Q

How can we describe the fluid nature of membranes?

A

Dynamic and flexible

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7
Q

Why does a slight temperature change not alter the membrane fluidity?

A

The composition of membranes are adapted to withstand a large range of temperatures

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8
Q

What is Spur Cell anemia?

A

When the plasma membranes of erythrocytes has up to 65% more cholesterol than normal

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9
Q

What are the two movement types in a membrane?

A
  1. Lateral

2. Transverse

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10
Q

What is apoptosis?

A

Programmed cell death

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11
Q

How does a highly saturated membrane affect fluidity?

A

Molecules pack closer together
Decrease fluidity
Increase rigidity

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12
Q

What facilitates the transverse movement of newly synthesised membrane?

A

ABC transport proteins (enzymes)

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13
Q

Where is the new membrane formed?

A

Formed from the ER to the golgi

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14
Q

What is transverse movement in the membrane?

A

Movement across the membrane (flipping to the other side)

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15
Q

What is the consequence of spur cell anemia on red blood cells?

A

RBC membrane is very rigid
so rbc can no longer morph to fit through small pores (e.g. capillaries)
Less able to function as successful rbc, due to increased cholesterol levels

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16
Q

What would a temperature decrease do to the fluidity of the membrane?

A

Energy associated with phospholipids decreases
Causes molecules to move closer together
Decreases membrane fluidity

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17
Q

What type of movement is required in newly synthesising membrane in order to make it structurally correct?

A

Transverse movement

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18
Q

List the common features of biological membranes

A
  • Asymmetrical
  • Fluid
  • Bi layers
  • Electrically polarised
  • Specific protein functions
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19
Q

Why is lateral movement so rapid?

A

Due to diffusion being a passive process

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20
Q

Why are phospholipids described as being amphipathic?

A

They are both hydrophilic and hydrophobic

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21
Q

What are lipid anchored proteins?

A

Membrane proteins covalently linked to a lipid

e.g. glycerophosphatidylinositol

22
Q

Why does the synthesis of new membrane cause the membrane shape to be deformed?

A

Membrane is synthesised on the the cytosilic membrane only

Causes a bowed shape - deformation

23
Q

What is phosphotidylserine ?

A

A phospholipid involved in apoptosis

24
Q

How much of the % cell weight is comprised of membrane carbohydrates?

A

membrane carbohydrates form 2% of cell weight

25
Q

What factors affect the membrane fluidity?

A

Temperature
Degree of saturation
Fatty acid length
Cholesterol content

26
Q

Where are new membrane synthesising enzymes found ?

A

Cytosilic surface of golgi apparatus

27
Q

What is the purpose of apoptosis?

A

Allows body to turnover cells without inducing inflammatory response

28
Q

Which membrane movement type is faster?

A

Lateral movement

29
Q

Where are membrane carbohydrates found on the membrane?

A

Facing away from the cytosol

30
Q

Where do the hydrophilic heads on the membrane face?

A

Extracellular surface

31
Q

Where are peripheral membrane proteins found on the membrane?

A

Located on extracellular (cytosolic) side

32
Q

What components can we expect in biological membranes?

A
  • Phospholipids
  • Cholesterol
  • Glycolipids

(not all membranes contain all 3)

33
Q

What facilitates movement in the membrane?

A

Enzymes

34
Q

Describe what the structure of peripheral membrane proteins is like

A
  • non covalent bonds
  • loosely associated with membrane - easier to extract
  • lipids and proteins can bind
35
Q

How does an increase in temperature affect membrane fluidity?

A

Energy associated with phospholipids increases
Molecules able to move apart
Increases fluidity

36
Q

Give examples of some membranes present in the body

A

Nuclear membrane
Plasma membrane
Mitochondrial membrane

37
Q

Explain what is meant by lateral membrane movement

A

Along the plane of the membrane

38
Q

How do the phospholipids arrange in bi layers?

A

They readily form bi molecular sheets in aqueous media

39
Q

How is fluid is the membrane when unsaturated?

A

Molecules can’t pack as closely together due to C=C double bonds
so increases fluidity
less rigidity

40
Q

What are 3 types of ABC enzyme proteins?

A

Floppase - Moves phospholipids from cytosilic to luminal side (inner -> outer surface), using ATP

Flippase - Moves phospholipids from outer to inner leaflet, using ATP

Synthase - Bidirectional movement of phospholipids, passive

41
Q

What other molecules do membrane carbohydrates associate with?

A

Both lipids and proteins

42
Q

Describe the structural features of integral membrane proteins

A

” ɒ helical transmembrane region

  • strong non covalent bonds
  • interlinked with membrane - difficult to extract
  • Pass through membrane once or multiple times
  • Hydrophobic side chains present on outer surface
43
Q

What is the advantage of cholesterol at high temperatures in the membrane?

A

Cholesterol maintains membrane stability (decreases fluidity)

44
Q

Outline how apoptosis occurs in cells

A
  1. Phosphatidylserine transversely transported to outer surface
  2. Causes cells to round up and form nodules
  3. Cells blister and burst
45
Q

What is the role of membrane carbohydrates?

A

Allow cells to interact with each other and the extracellular membrane

46
Q

What effect does cholesterol have on the membrane?

A

OH group forms H bonds between the phospholipid hydrophobic tails
Disrupting the interactions between the fatty acid chains
Prevents strong bonding in chains
Increases fluidity - esp. at low temp

47
Q

What is the significance of ABC enzyme proteins?

A

They are crucial in establishing membrane asymmetry

48
Q

Name the different proteins present in a membrane

A

Integral membrane proteins
Peripheral membrane proteins
Lipid anchored proteins

49
Q

Why is the membrane described as fluid mosaic?

A

Fluid - components able to move around

Mosaic - composed of many different Proteins

50
Q

How is apoptosis initiated?

A

The movement of phosphotidylserine from inner to outer surface signals to cells apoptosis will occur

51
Q

What would an increase in fatty acid length do to membrane fluidity?

A

More interactions and bonds form between chains
Fluidity would decrease
Increase rigidity

52
Q

Why is transverse movement slow?

A

Relatively significant amount of energy required to move a polar molecule through a hydrophobic region to opposite side of membrane

FLC (34 decks)

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