Week 3 MPW Lecture 3 Flashcards
What are the different types of membrane lipids?
3 main types:
a) Phospholipids (also called phosphoglycerides)
b) Sphingolipids; (contain NH instead of H where the 2 tails bind, mostly trans double bonded)
c) Sterols; like Cholesterol
What affect does cis double bonds have on lipids?
Make the lipid chain go off at an angle, making them less linear. And therefore are more disorder making the lipid more fluid.
What affect does trans double bonds have on lipids?
Straight chains making the lipids more ordered so the bilayer acts more like a gel
Do cells prefer trans or cis double bonds?
Normal cell usually like to be fluid to allow molecules to be transported across the membrane therefore needs cis lipids.
What does heat do to the membranes?
More heat more movement = fluid
a) Less heat less movement = gel like
Which is thicker, gel-like consistency or the fluidlike consistency cell membrane?
Gel like because it is more ordered
What is the function of cholesterol?
It’s a flat lipid and it packs against other flat lipid, making the lipids longer = more gel like. Reduces movement.
There are many headgroups that link to the hydrophobic tail, how do they affect the membrane?
Phosphatidyalcholin (PC) is cylindrical so it packs into flat bilayers. However, Phosphatidylethanolamine (PE) has a smaller head and therefore makes the bilayer curved.
How can the size of the headgroup affect the membrane shape?
Smaller lipid heads make the membrane curve inwards.
What are other ways that the cell uses to fix the curvature of the membrane?
Include
a) Lipid composition
i) The chain composition
ii) Headgroup composition
b) Membrane proteins
c) Cytoskeleton
i) Actin
ii) Microtubule
d) Scaffolding
i) Indirect
ii) Direct (positive or negative)
e) Helix insertion
What is an w3-unsaturated lipid?
A polyunsaturated lipid
