Membrane Cytoskeleton Interactions and Asymmetry

?
  • Created by: LucyLaa
  • Created on: 13-10-18 20:30
Why are cells asymmetric?
Proteins have different functions e.g. channels, receptors, enzymes, carriers, cell-cell recognition, cytoskeleton, intracellular transport etc.
1 of 23
What is an erythrocyte?
Red Blood cell
2 of 23
What is an RBC ghost?
A clean preparation of plasma membrane when haemoglobin washed away
3 of 23
Why is an RBC biconcave?
Increases SA to carry haemoglobin
4 of 23
How are RBC ghosts used?
Run on SDS page gels, agarose gel under electric field and use western blot, take gel and stain separated proteins, see simple protein composition
5 of 23
What does spectrin form?
Dimers
6 of 23
What can mutations in spectrin cause?
Fragility --> patients can have haemolytic anemia
7 of 23
Name 3 peripheral proteins in the cytoskeleton of RBCs
Spectrin, Actin (in a complex with tropomyosin, band 4.1 and adducin), and Ankryin
8 of 23
Name 2 transmembrane proteins
Glycophorin and Band 3
9 of 23
Which moves more rapidly: proteins or phospholipids?
Phospholipids (less constrained than proteins)
10 of 23
How are proteins constrained?
Can be: tethered to cytoskeleton; mesh-work close to membrane acts as a diffusion barrier; tight junctions prevent free movement of proteins into different domains
11 of 23
In which leaflet is the segregation of lipids?
Outer leaflet --> tight junctions localise the lipids
12 of 23
How is lipid movement restricted?
Binding to particular proteins; segregated into domains (e.g. lipid rafts); physical barriers (e.g. tight junctions)
13 of 23
What is the glycocalyx?
Sugary layer on the outside of cells formed by glycolipids and glycoproteins
14 of 23
What is the function of the glycocalyx?
Protection, quick responses in signalling e.g. Blood Group System
15 of 23
Which blood group is the universal donor?
O
16 of 23
Which blood group is the universal acceptor?
AB
17 of 23
Why might the phospholipid bilayer be asymmetric?
Inner surface may be negatively charged to maintain electrochemical gradient, or certain proteins may be needed in signalling cascades
18 of 23
What is the enzyme that equilibrates lipids when more phospholipids are added to one side of the bilayer?
Scramblase
19 of 23
What does this enzyme do within the membrane?
It flips the phospholipid molecules so they are symmetrical
20 of 23
What is the enzyme that catalyses the flipping of specific phospholipids to cytoplasmic monolayer using ATP?
Flippase
21 of 23
What does aminophospholipid translocase do to the membrane?
It transports phosphatidylserine and phosphatidylethanolamine from one side of a bilayer to another
22 of 23
Why is phospholipid asymmetry important?
Coagulation (translocase activity inhibited so phosphatidylserine ends up in outer leaflet and provides nucleation site for cascade); Scott's Disease (deficiency of scramblase so no clotting); cell recognition and apoptosis
23 of 23

Other cards in this set

Card 2

Front

What is an erythrocyte?

Back

Red Blood cell

Card 3

Front

What is an RBC ghost?

Back

Preview of the front of card 3

Card 4

Front

Why is an RBC biconcave?

Back

Preview of the front of card 4

Card 5

Front

How are RBC ghosts used?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Cell and Molecular Biology resources »