[FMS] CBS - lipid membrane + structure

Question 1

membranes are Amphipathic, what does this mean?

Answer 1

“Amphipathic” : polar head group and non-polar FA tail

OR

Hydrophilic head group, hydrophobic FA tail

Question 2

what lipid is used as an energy store

Answer 2

triacylglycerols

Question 3

how many classes of lipids are there, and what are they:

Answer 3

6 -
saturated and unsaturated fatty acids,
triacylglycerols, phospholipids, glycolipids and cholesterol)

Question 4

what lipid is used as a precursor for vitamins

Answer 4

vitamin D

Question 5

what are the examples of steroid hormones (lipids)

Answer 5

Steroid hormones ie oestrogen, testosterone, and cortisol

Question 6

what are the examples of bile acids (lipids)

Answer 6

cholic acid

Question 7

this questions is regarding how fatty acids are labelled - what does this labelling indicate:

18: 1 △ 9

Answer 7

Question 8

how would you write myristic acid

Answer 8

14:0

Question 9

how would you write plamitic acid

Answer 9

16:0

Question 10

how would you write stearic acid

Answer 10

18:0

Question 11

how would you write oleic acid

Answer 11

18:1△9

Question 12

how would you write linoleic acid

Answer 12

18:2△9

Question 13

what is a TAG made of and where is it stored

Answer 13

Triacyclglycerols (triglycerides) TAG. Ester of three fatty acids and glycerol. Stored in adipose tissue.

Question 14

what is a fatty acid made of

Answer 14

Long-chain aliphatic carboxylic acids

Question 15

what 3 things are phospholipids made of - what name is given to these 3?

Answer 15

Phospholipids are composed of:
- glycerol
- two fatty acids
- a phosphate containing head group.

^ these are reffered to as PHOSPHATIDYL GROUPS

Question 16

what are phospholipids useful for and which part is hydrophobic/ hydrophilic

Answer 16

The head group and the phosphate are hydrophilic and the fatty acids are
hydrophobic. These chemical properties are key to the role in forming membranes.

Question 17

where are fatty acids metabolised and what do they produce?

Answer 17

metabolised via beta-oxidation pathway to generate ATP

Question 18

what does NEFA stand for in regards to fatty acids?

Answer 18

NEFA - non-esterified fatty acids

Question 19

what are the 4 common head groups in phospholipids, and what are their respective phospholipid names?

Answer 19

choline, serine, ethanolamine and inositol. These phospholipids are called
Phosphatidylcholine PC, Phosphatidylserine, PS Phosphatidylethanolamine PE and
Phosphatidylinositol PI.

Question 20

what 3 things is a glycolipid made from

Answer 20

Glycolipids are composed of glycerol, two fatty acids and a head group containing sugars.

Question 21

are lipid bilayers symmetrical or asymmetrical?

Answer 21

asymmetrical -2 halves have different lipid composition

Question 22

in lipid bilayers, out of these 4: PC, PS,SPH,PE - which faces the extracellular environment and which faces the cytosolic side?

Answer 22

PC and SPH face the extracellular environment
PS and PE face the cytosolic side

REMEMBER ‘SEEPS’ ie it SEEPS inside (SEEPs stands for PS + PS)

Question 23

what is membrane fluidity?

Answer 23

Fluidity is the ease with which lipid molecules move about in the plane of the bilayer
important in the regulation of membrane function (e.g. movement of proteins, signalling, exocytosis)

Question 24

what increases fluidity

Answer 24

1. increase number of short chain FA = reduced Van der Waals interactions between FA
2. kinks in unsaturated FA = reduced Van der Waals interactions with other lipids

Question 25

what decreases fluidity

Answer 25

High cholesterol content restricts the random movement of polar heads, thus making lipid bilayer 'ordered' and decreases fluidity (therefore highly ordered parts of lipid rafts are rich in cholesterol)

Question 26

what is a lipid raft?

Answer 26

specialised membrane microdomain

Question 27

are lipid rafts ordered or unordered, what effect does that have on fluidity?

Answer 27

more ordered = less fluid = increased CHOLESTEROL, SPHINGOMYELIN AN DGANGLIOSIDES

Question 28

whats the function of a structural membrane protein? give an example

Answer 28

function = Cell-cell contact; attachment of cytoskeleton example = actin, spectrin, ankyrin

Question 29

whats the function of a receptor membrane protein? give an example

Answer 29

function = Signal recognition and transmission example = Insulin receptor, Glucagon receptor

Question 30

whats the function of an ion channel membrane protein? give an example

Answer 30

function = Maintenance of ionic gradients and transmission example = Acetylcholine (nicotinic) receptor, GABAA receptor

Question 31

whats the function of a transporter membrane protein? give an example

Answer 31

function = Import and export of substrates example = glucose transporters

Question 32

whats the function of an enzyme membrane protein? give an example

Answer 32

function = catalysis example = adenylate cyclase

Question 33

what are the 3 ways membranes are organised

Answer 33

Integral (intrinsic) proteins - Transmembrane spanning domains are α-helices or β-sheets Anchored proteins - covalent bonds with fatty acids Peripheral (extrinsic) proteins - by ionic interactions with integral proteins or with polar head group of phospholipids REMEMBER - 'peripheral' has an 'I' = IONIC Anchored = covAlent

Question 34

what are 2 examples of anchored proteins?

Answer 34

- glycolipid: enzyme alkaline phosphatase - fatty acyl: RAS (signalling G-protein)

Question 35

whats an example of a peripheral protein

Answer 35

spectrin: important structural protein on the cytoplasmic surface of erythrocytes interacts with other proteins such as ankyrin

Question 36

how do peripheral, anchored, and integral membrane proteins react when treated with high salt/ urea, detergent, and phospholipase (draw a table to help)

Answer 36

Question 37

what is a phospholiapse and what does it do

Answer 37

phospholipase definition = enzyme class that binds to membrane function = selectively hydrolyse components of phospholipids

Question 38

what are the 4 phospholipases and where are they located in a phospholipid?

Answer 38

Phospholipase A1 = (PLA1) Phospholipase A2 = (PLA2) Phospholipase C = (PLC) Phospholipase D = (PLD)

Question 39

what is sphingomyelin made of?

Answer 39

choline, phosphate, ceramide

Question 40

what is a ceramide made up of

Answer 40

Some lipids replace glycerol with sphingosine. Sphingosine and a single fatty acyl chain form a unit called ceramide THEREFORE cermaide made up of sphingosine and fstty acyl chain

Question 41

what is a GM1 ganglioside made up of

Answer 41

Question 42

what diseases is caused by the accumulation of GM2 ganglioside

Answer 42

Tay Sachs Disease (TSD)

Question 43

where does the accumulation of GM2 gangliosides occur in TSD (Tay-Sachs Disease)

Answer 43

in the lysosomes of neurones – therefore its a lysosomal storage disease

Question 44

is TSD autosomal dominant or recessive?

Answer 44

Autosomal recessive disease

Question 45

what is Zellweger syndrome?

Answer 45

complete or partial loss of peroxisomes - mutations is one of 13 PEX genes called peroxins

Question 46

which diseases is affected by the peroxisomes

Answer 46

Zellweger syndome - ZSD

Question 47

do the lipids membrane and structure quiz and then come back!!

Answer 47

https://keats.kcl.ac.uk/mod/quiz/view.php?id=7540174

Question 48

How does the phospholipid bilayer form?

Answer 48

Spontaneously forms bi-layer in aqueous environment.

Question 49

what makes lipid bilayers asymmetrical?

Answer 49

Phosphatidylcholine and sphingomyelin face the extracellular environment. Phosphatidylserine and phosphatidylethanolamine face the cytosolic side. REMEMBER: SEEPS inside (PE, PS = inside on cytosol)

Question 50

What are 5 properties of lipid rafts?

Answer 50

- They have specialised membrane microdomain - More ordered – less fluid - Increased level of cholesterol, sphingomyelin and gangliosides - Allows close interaction between receptors and signalling molecules

Question 51

What disease occurs when the metabolism of GM2 is deficient?

Answer 51

Tay Sachs Disease

Question 52

What disease occurs when the metabolism of GlcCer is deficient?

Answer 52

Gaucher’s disease

Question 53

What disease occurs when the metabolism of Cer is deficient?

Answer 53

Farber disease

Question 54

What is a diagnostic observation of TSD?

Answer 54

Infantile TSD patients have a characteristic observation of a cherry-red spot

Question 55

what is an integral protein

Answer 55

Integral (intrinsic) proteins – embedded in lipid bilayer, most span the entire bilayer. **Transmembrane spanning domains are α-helices or β-sheets**

Question 56

what is an anchored protein

Answer 56

Anchored proteins – anchored to membrane by **covalent bonds** with fatty acids

Question 57

what is a peripheral protein

Answer 57

Peripheral (extrinsic) proteins – attach to membrane surface by **ionic interactions** with integral proteins or with polar head group of phospholipids

Question 58

what 3 components make up a 'phosphatidyl' group

Answer 58

Phosphate, glycerol and fatty acid

Question 59

whats the structure of steroids

Answer 59

**multi-ring hydrophobic region** and a **hydrophilic region.**

Question 60

what is cholesterol made from how can it be synthesised?

Answer 60

**Cholesterol is a steroid** that forms part of membranes and is the **precursor of steroid hormones.** It can be **synthesised de novo or obtained from diet.**

Question 61

Where does PLA1 cleave?

Answer 61

SN-1 position Act between 1st fatty acid and glycerol

Question 62

Where does PLA2 cleave?

Answer 62

SN-2 position Acts between second fatty acid and glycerol Erachadonic acid

Question 63

Where does PLD cleave?

Answer 63

Act between phosphate and phospholipid head group

Question 64

Where does PLC cleave?

Answer 64

Acts between glycerol and phosphate