Membranes & Proteins Flashcards by makeen baroudi

Function of membranes

functional barrier
energy source
organise & regulate enzyme activity
facilitate signal transduction
supply substrates for biosynthesis
protein recruitment platform

How well did you know this?

Not at all

Perfectly

What do membranes consist of

lipids

- proteins

How well did you know this?

Not at all

Perfectly

What are the three types of membrane lipids

glyceropphospholipids (phospholipids)
sphingolipids –> glucoshpingolipids (glycolipids)
sterols

How well did you know this?

Not at all

Perfectly

What are fatty acid chains

long aliphatic carbon chains

- terminal carboxylic acid

How well did you know this?

Not at all

Perfectly

How does hydrophobic affect water molecules

Reorganise

How well did you know this?

Not at all

Perfectly

What happens if hydrophobic molecules cluster together

smaller no. of water molecules affected —> lower energy cost

How well did you know this?

Not at all

Perfectly

What could lipids form

bilayers

- micelles

How well did you know this?

Not at all

Perfectly

How are fatty acids named

XX:Y n-y

XX: C atoms
Y: =s
n-y: position of 1st double bond (starting at methyl terminus)

How well did you know this?

Not at all

Perfectly

Describe saturated lipids

no =

- straight

How well did you know this?

Not at all

Perfectly

Describe unsaturated lipids

contains =
cis = —> 30 degrees kink
trans = —> no effect

How well did you know this?

Not at all

Perfectly

What does diff. in length and saturation of fatty acids influence

How phospholipids pack against one another

How well did you know this?

Not at all

Perfectly

Where does chemical diversity in glycerophospholipids arise from

combination of two fatty acids
sn-1 position linkage
head group linkage

How well did you know this?

Not at all

Perfectly

Describe sn-1 fatty acid (in glycerophospholipids)

saturated

- monounsaturated

How well did you know this?

Not at all

Perfectly

Describe sn-2 fatty acid (in glycerophospholipids)

more monounsaturated

- polyunsaturated

How well did you know this?

Not at all

Perfectly

What are the anaionic phospholipids

How well did you know this?

Not at all

Perfectly

What is the charge of zwitterionic phospholipids

Zero

How well did you know this?

Not at all

Perfectly

What do PS & PE glycerophospholipids contain and what does that help towards

Reactive amines

H-bonds

How well did you know this?

Not at all

Perfectly

Which glycerophospholipids are bulky and what does that help with

PI, PC & CL

- their packing

How well did you know this?

Not at all

Perfectly

What lipids are found in mitochondria

PG & cardiolipins

How well did you know this?

Not at all

Perfectly

How are PIPs generated

Head group phosphorylation at positions 3, 4 & 5 of phosphatidylinositol

How well did you know this?

Not at all

Perfectly

How many different PIP species are there

How well did you know this?

Not at all

Perfectly

How saturated are the tails of PIP

Saturated

Polyunsaturated

How well did you know this?

Not at all

Perfectly

What is the most abundant PIP in mammalian plasma membrane, where is it found

PI(4,5)P2

Inner leaflet of plasma membrane

How well did you know this?

Not at all

Perfectly

What does PTEN protein do

Convert PI(3,4,5)P3 to PI(4,5)P2

How well did you know this?

Not at all

Perfectly

What do sphingolipids consist of

- sphingolipids base - N-acyl chain - head group

What is the most common sphingolipid

Sphingomyelin (SM)

What head group does sphingomyelin have

The amide gp on sphingolipids have the ability to h bond, what does that help with

Interactions of sphingolipids with cholesterol and polar parts of proteins

Describe N-acyl chain in sphingolipids

- more saturated | - longer than acyl chains of glycerophospholipids

What are the different head groups of glycosphingolipids

Oligosaccharides | sugar building blocks

Where are glycosphingolipids found

Outer leaflet of membrane, 5% of membrane

Which groups are exposed to cell surface in glycosphigolipids

- sugar - help with cell-cell adhesion - membranes act as recognition sites

Name 3 components of glycolipids

Ganglioside GM1, 2, 3

Where do h bonds form in glycolipids

Between sugars and lipids tail

What is self-aggregation of GM1 driven by

Sugars

What groups do sterol have

- hydroxyl group | - hydrocarbon tail

What is the most common sterol in animals

Cholesterol

What sterols is found in yeast & fungi membrane

Ergosterol

What sterols are found in plants

- sitosterol | - stigmasterol

What can cholesterol shape allow it to do

Align better with saturated site chains

Cholesterol interaction with POPC

OH group is not buries in complex

Describe interaction between cholesterol and sphingomyelin

- H bond: OH of cholesterol & NH of sphingolipid | - OH of cholesterol masked by polar head of sphingomyelin

What are the three different membrane curvatures

- cylindrical (flat membrane) - conical (negative membrane) - inverted-conical (positive membrane)

What lipids are cylindrical

- PC | - PS

What lipids are conical

- PE | - PA

What lipids are inverted-conical

- lysosome-GPLs | - phosphoinositides

What does -ve curvature of PE lead to

- generation of non-bilayer | - eg fusion

What are the types of lipid diversity

- chemical/structural | - compositional

Describe the lipid asymmetry in erythrocytes membranes

- 50% cholesterol - high conc. of PC & SM in outer leaflet - high conc. of PS & PE in inner leaflet

Give an example of functional importance of lipid asymmetry in cell signalling

- PS translocate to extra cellular layer when cell dies - signals neighbouring cells, macrophages - phagocytise dead cell

How does movement of PS occur

Via scramblases

What direction are secondary signalling messengers oriented towards

Interior of cell

When does lipid interdigitation occur & what does it do

- Lipid length asymmetry in membranes | - Coupled two leaflets together

What are the directions of lipid movement

- rotational - lateral - transverse

What is rotational movement

- spinning of lipids around axis - doesn’t alter positions - affects interactions with neighbouring molecules

What is lateral movements

- neighbouring lipids exchange places | - lipids change position within bilayer

What is transverse movement

- exchange of molecules between leaflets | - lipids move across bilayer by transverse diffusion or proteins

What is the difference between lipids composition of tumour tissues (lung cancer) and normal tissues

- PI higher in tumour | - SM lower in tumour

What is different about lipid composition in tumour tissues in breast cancer

PI, PE, PC and SM sig. higher in tumour

Which lipid is increased in type ii diabetes, Alzheimer’s and CF

Ceramide

What lipids are increased in outer leaflet of thalassaemic and diabetic red cells

- PS | - PE

What phases are covered by lamellar phase

- lamellar liquid crystalline (liquid disorder) - solid gel - liquid-ordered

What does the adopted phase depend on

Lipid structure

What are lipid droplets

- storage organelles - maintain lipid - maintain energy homeostasis

What are hydrophobic cores of neutral lipids enclosed by (droplets)

Phospholipid monolayer | - has specific proteins

Where do lipid droplets originate from

- ER

When are lipid droplets initiated

Neutral lipids are produced

What do neutral lipids result from

- esterification of a fatty acid to triacylglycerol or sterol to sterol ester

Where are neutral lipids dispersed at low concs.

Between leaflets of ER bilayer

What can impairment of fatty acid storage in lipid droplet result in

- type 2 diabetes | - non-alcoholic fatty liver disease

Describe spontaneous transverse movement

- bidirectional - no energy - non-specific

describe P-type flippase transverse movement

- inward movement - ATP - specific

Describe ABC flippase transverse movement

- outward - ATP - specific

Describe scramblase transverse movement

- bidirectional - no energy - non-specific - Ca2+ dependent

Membranes & Proteins Flashcards

(74 cards)