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Fundamentals of Science I > Cell Membranes I > Flashcards

Cell Membranes I Flashcards

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Biology 101 flashcards
1
Q

What are the layers of the cell?

A 
Apical = Top Part 
Lateral =  Middle Part
Basal = Bottom Part
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2
Q

What is the structure of the plasma membrane like?

A

Lipid bilayer (phospholipids and others) combined with proteins (structural) and carbohydrates located in the outer monolayer.

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3
Q

Name some single membrane examples.

A

Lysosome
Endoplasmic Reticulum
Golgi Apparatus
Vacuoles

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4
Q

Name some double membrane examples.

A

Plasma Membrane
Mitochondria
Chloroplasts
Nuclear Envelopes.

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5
Q

What is an example of a common lipid?

A

Phosphoglycerides = Phospholipids derived from glycerol.

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6
Q

What are sphingolipids?

A

Phospholipids derived from sphingosine.

Amino alcohol which contains long unsaturated hydrocarbon chain

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7
Q

What is the ratio of lipids?

A 
Phospholipids = 75% 
Cholesterol = 20%
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8
Q

What is the structure of lipids?

A 
Hydrophilic head (negatively charged) 
Hydrophobic tail (uncharged)
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9
Q

What is the positioning of the lipid molecule?

A

Tails meet in the inner region of the membrane = AWAY FROM THE WATER.
Heads meet in the outer region of the membrane = TOWARDS TO THE INTRACELLULAR / EXTRACELLULAR FLUID.

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10
Q

What is the number of main phosphoglycerides?

A

3 main phosphoglycerides.

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11
Q

What is the number of main sphingolipids?

A

1 main sphingolipid.

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12
Q

What does phospholipids in water create?

A

Forms into micelles.

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13
Q

What are liposomes?

A

Spherical vesicles of at least one lipid bilayer.

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14
Q

What are lipids normally composed by?

A

Phosphatidylcholine.

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15
Q

How can liposomes be formed artificially?

A

Disrupts cell membranes.

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16
Q

What are liposomes used as?

How does it carry out this function?

A

Vehicle for administration of nutrients and pharmaceutical drugs.
Membrane of liposome will FUSE with membrane of cell to deliver the content into the cell.

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17
Q

Where is cholesterol normally present ?

A

Present in animal cell membranes.

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18
Q

What is the purpose of cholesterol?

A
  • Regulates membrane fluidity.

- Allows presence of protein channels in the membrane.

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19
Q

How does it regulate membrane fluidity?

A

Hydroxyl head of cholesterol will attach to the phospholipids and DISRUPT non - covalent bonds between fatty acids.

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20
Q

What are glycolipids?

A

Lipids with carbohydrate attached by covalent - bond surface of the eukaryotic membrane.

21
Q

What is the function of glycolipids?

A

Maintains membrane stability and facilitates cellular recognition in immune response.

22
Q

What is glycocalyx?

A

Glycoprotein and glycolipid hybrid which surrounds cell membranes of some bacterial cells.

23
Q

How can lipid cell membrane fluidity vary?

A
  • Temperature
  • Fatty Acid Composition
  • Chain Length
  • Degree and Extent of saturation
  • Cholesterol content
24
Q

What does a longer chain mean in terms of a lipid chain?

A

MORE interaction.

25
Q

Why does the structure of lipids become more rigid?

A

There is a very TIGHT packing.

26
Q

What is the structure of lipids like during low temperature?

A

Without the cholesterol there is NO rigidity.

When cholesterol is ADDED : FLUIDITY INCREASES.

27
Q

What is the structure of lipids like during high temperatures?

A

Without the cholesterol there is RIGIDITY.

When cholesterol is ADDED : FLUIDITY DECREASES.

28
Q

What is a sickness which can lead to decreased membrane fluidity?

A

Spur Cell Anaemia.
This is very common in patients with liver cirrhosis.
LEADS TO CELL DEATH.

29
Q

What is the solution to spur cell anaemia?

A

Liver Transplant.

30
Q

What is the 2 modes of transport for lipids?

A

Lateral Movement

Transverse Movement

31
Q

Explain lateral movement of lipids.

A

Free movement of molecules and therefore, the lateral movement is VERY RAPID.

32
Q

Explain transverse movement of lipids.

A

‘Flip - flopping’ movement and therefore, the transverse movement is VERY SLOW.
Requires action of three enzymes

33
Q

What are the 3 enzymes required to adjust the cell membrane fluidity?

A

Flippase
Floppase
Scramblase

34
Q

What is the purpose of flippase?

A

Moves phospholipids from the outer to the inner leaflet. (REQUIRES ATP).

35
Q

What is the purpose of floppase?

A

Moves phospholipids from INNER to OUTER leaflet.

REQUIRES ATP

36
Q

What is the purpose of scramblase?

A

Bidirectional moment.

37
Q

Which membrane does scramblase work on?

A

ER membrane.

38
Q

Which membrane does flippase work on?

A

Golgi Membrane or Plasma Membrane.

39
Q

What is the process of phagocytosis?

A

1) Recruitment to find the ‘eat - me’ signals.
2) Recognition of ‘eat - me’ signals // Engulfment of corpse.
3) Process and Degrade the corpse.
4) Pos engulfment consequences. (Releases anti - inflammatory cytokines.)

40
Q

What molecules is released the MOST when cells are dying?

A

Phosphatidylserine.

41
Q

What are the 3 main integral membrane proteins?

A

Alpha - Helix = Recognition / Receptors.
Helical Bundle = Enzymes / Transporters / Receptors.
Beta - Barrel = Transporters (channel proteins).

42
Q

What is the main trans - membrane domain?

A

Alpha - Helix

43
Q

What bonds do integral membrane proteins have?

A

Strong non - covalent bonds.

44
Q

Where are peripheral membrane proteins located?

A

Located on either side of thee membrane.

45
Q

What bonds do peripheral membrane proteins have?

A

Associated by non - covalent bonds.

46
Q

How are carbohydrates attached?

A

Covalently linked to proteins or lipids of the external layer.

47
Q

What is the function of carbohydrates?

A

Involved in cell - cell interactions / cellular recognition and cell adhesion.

48
Q

What is the function of the nuclear pore complex?

A

Exchange of components and prevention of the transport of non - desired material.

Fundamentals of Science I (45 decks)

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