1. Lipids, Proteins and Membrane Structure Flashcards Preview

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Flashcards in 1. Lipids, Proteins and Membrane Structure Deck (44)
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0

Why would different regions of a cell membrane have different proteins?

Different regions can have different functions e.g. Adherence, secretion/absorption, synapses, interaction with basement membrane etc.

1

What proportion of the dry weight of a membrane do lipids make up?

40%

2

What proportion of the dry weight of the membrane do proteins make up?

60%

3

What else makes up the dry weight of the membrane bilayer.

Carbohydrates

4

When hydrated, how much of the total weight does water make up and how is water associated with the membrane?

20%
Hydrogen bonded to the cell membrane surface

5

What four groups make up a phospholipid molecule?

Polar head group
Phosphate group
Glycerol
Fatty acid chains

6

What are the most predominant lengths of fatty acid chains?

C16
C18

7

What can produce a kink in the phospholipid?

Cis orientated double bond in a fatty acid tail

8

What four chemicals can act as polar heads?

Choline
Amines
Amino acids
Sugars

9

What makes a glycolipid different to a phospholipid?

Carbohydrate molecule instead of a phosphate head

10

What are the two types of glycolipid?

Cerebrosides
Gangliosides

11

What type of head group is present on a ganglioside glycolipid?

Oligosaccharide

12

What type of head group is present on a cerebroside lipid?

Sugar monomer

13

What are the forces that interact between hydrophobic tails in a membrane?

Van der Wall's forces

14

What are the two types of lipid bilayers that can form?

Phospholipid bilayer
Lipid mycelle

15

What 4 types of motion can phospholipids undergo?

Flexion (vibration)
Rotation
Lateral diffusion
Flip flop

16

Which type of phospholipid motion requires the most energy and why?

Flip flop as it is the least thermodynamically favourable

17

What do the Cis bonds in the fatty acid tails of phospholipids result in?

Reduced phospholipid packing
More movement
More fluidity of membrane

18

What does our diet need to include for phospholipids and where can we get this from?

Polyunsaturated fats
Vegetable oils
Tuna/Salmon
Seeds

19

What property does the planar ring in cholesterol have?

Rigidity

20

What percentage of lipids in a phospholipid bilayer are cholesterol?

45%

21

How does cholesterol interact with the phospholipid bilayer?

Locks onto adjacent phospholipid via a hydrogen bond

22

How does cholesterol reduce fluidity of the membrane at high temperatures?

Reduces the phospholipid's fatty acid chain's motion

23

How does cholesterol increase fluidity of the membrane at low temperatures?

Reduced phospholipid packing

24

What is cholesterol's overall effect on the membrane?

Maintains a constant fluidity at a wide range of temperatures

25

What are the 3 functional pieces of evidence for proteins existence in the membrane?

Facilitated diffusion
Ion gradients
Specificity of cell responses

26

What are the 2 biochemical pieces of evidence for protein existence in the membrane?

Membrane fractionation
Freeze fracture

27

What type of mobility can proteins NOT do in membrane bilayers and why?

Flip flop
Requires too much energy as they have large hydrophilic moieties which associate with the polar heads and water on the outsides of the membrane

28

What are the 3 types of mobility proteins can do in bilayers?

Conformational change
Rotation
Lateral diffusion

29

What restricts protein movement in bilayers?

Protein aggregation
Tethering (e.g. Cytoskeleton)
Interaction with other cells