Lipid Membrane 1

Question 1

What characteristics are important for membranes?

Answer 1

Electrical characteristics

Question 2

What can change the properties? HINT P

Answer 2

Protein changes the properties

Question 3

Membranes are dynamic - true/false?

Answer 3

True

Question 4

What experiment was essential to disovering fluid mosaic of membranes?

Answer 4

Cryofracture experiment

Question 5

What does the fluid mosaic model show?

Answer 5

That the membrane is formed from lipid bilayers with proteins in the middle, that are arranged in an electrically stable way

Question 6

What can bending the protein do in terms of energy?

Answer 6

By bending the proteins, can get the better energetic configuration and they can have multiple transmembrane spans

Question 7

Are proteins always directly attached to membranes themselves?

Answer 7

No you can have proteins that are attached to other protein residues.

Question 8

What are the membrane functions? HINT 8

Answer 8

• Compartmentalisation: contains the cell - the intracellular components
• Membrane isolates the cell depending on permeability and this allows formation of membrane voltage
• Receives signals by expressing receptors
• Signals need to be transcribed later on so the membrane holds the components that forms the signalling cascade.
• Scaffold for biochemical activity – membrane rafts
• Transport: it is a selectively permeable barrier
• Receptors: responds to external signals and allows for cellular interactions with each other
• Membrane enables energy transduction

Question 9

What is lipid bilayer of membrane made up of?

Answer 9

Hydrophilic (love water) phospholipid head groups on either side and associated fatty acids which are hydrophobic (hate water).

Question 10

What are the 3 most important membrane lipids?

Answer 10

Phospholipids, cholesterol and sphingolipids

Question 11

What is the formula for glycerol?

Answer 11

CH2OH

Question 12

Which is healthier - unsaturated/saturated?

Answer 12

unsaturated is healthier

Question 13

Are phospholipids amphipathic and if so what does this mean?

Answer 13

Yes, phospholipids are amphipathic and this means that they are mostly lipid like but they have a hydrophilic region at one end. BOTH HYDROPHOBIC AND HYDROPHILIC

Question 14

Is Phosphatidylinositol an important molecule in regards to molecule cascades?

Answer 14

Yes Phosphatidylinositol is an important molecule in regards to molecular cascades.

Question 15

What makes up a phospholipid?

Answer 15

3 carbons, 2 fatty acids and a phosphate

Question 16

What phospholipid has the base choline?

Answer 16

Phosphatidylcholine

Question 17

What phospholipid has the base estanolamine?

Answer 17

Phosphatidylethanolamine

Question 18

What phospholipid has the base serine?

Answer 18

Phosphatidylserine

Question 19

What phospholipid has the base ionistol?

Answer 19

Phosphatidylinositol

Question 20

What is phosphatidylcholine made up of?

Answer 20

Fatty acid, glycerol, phosphate group and choline

Question 21

How is a sphingolipid made?

Answer 21

Formed by a sphingosine and a fatty acid

Question 22

What do sphingolipids have structural and biological functions in?

Answer 22

In the human epidermis

Question 23

Are ceramides apart of extracellular lipids and if so what do they do?

Answer 23

Ceramides are apart of extracellular lipids and they act as a barrier to the skin

Question 24

Why is vitamin C good for your skin?

Answer 24

Vitamin C creams are good for your skin as it gives your skin’s barrier strength to keep mosturise in it.

Question 25

What do sugars normally found in extracellular spaces allow for?

Answer 25

They allow for many interactions

Question 26

What is cholesterol most important for?

Answer 26

Functionality of the membrane

Question 27

Is cholesterol an amphipathic molecule?

Answer 27

Yes cholesterol is an amphipathic molecule

Question 28

Why is cholesterol bad for cardiovascular health?

Answer 28

Cholesterol is bad for cardiovascular health as it leads to very rigid membranes which are then very fragile and can cause build up in the heart and an accumulation of oxidative stress.

Question 29

What is DHA?

Answer 29

Docosahexanoic acid

Question 30

What is EPA?

Answer 30

Eicosapentaenoic acid

Question 31

What is AA?

Answer 31

Arachidonic acid

Question 32

What must fatty acids have?

Answer 32

They must have some structure through rigidity but must be flexible

Question 33

4 things to describe saturated fatty acids:

Answer 33

No double bonds Space saving More rigid Fragile membranes

Question 34

Do saturated fatty acids normally have long/short carbon chains?

Answer 34

Long carbon chains

Question 35

What is the main idea with saturated fatty acids?

Answer 35

Idea is that there’s nothing that can be added easily as all the carbons are covalently bonded elsewhere.

Question 36

What are saturated fatty acids useful for in terms of membranes?

Answer 36

They are useful to embed the membrane with rigidtiy

Question 37

What problems arises with saturated fatty acids?

Answer 37

Problem is that when a structure is too rigid it is also therefore too fragile. If it is too fragile then the membrane cannot adapt to changing environment and this therefore interferes with the membrane function.