Lecture 7 and 8 Flashcards
Membrane lipids are ______/
Amphiphilic
How thick is the lipid membrane?
5nm (50 angstrom)
What name is given to the carboxl and methyl end of a fatty acid?
Delta and omega (respectively)
Give an example of a glycerophospholipid
Phosphatidyl-choline
What is the structure of phosphatidyl-choline?
Choline, phosphate, glycerol, hydrocarbon tails
Why do membrane lipids favor a bilayer of two leaflets over a micelle?
Cylindrical shape
What do membrane sheets favour the formation of?
Liposomes (membrane lipid balls, energetically favorable)
What are exosomes and what do they do?
Liposomes released by cells, cell to cell communication
Membranes can be split into glycerophospholipids and ________
Sphingolipids (S for serine linker)
What three lipid components can comprise a membrane?
Phosphoplipids, glycolipids, cholesterol
Name two categories of phospholipids.
Amino and choline phospholipids
Name 4 glycerophospholipids
Phosphatidyl: - Inositol -Athanolamine -Serine Choline
What are the three coponents of cholesterol?
Polar head group
Rigid steroid ring structure
Nonpolar hydrocarbon tail
How do cholestrol interact with glycerophospholipid?
Associates with head the lipid, it becomes more densely packed, less fluid, less permeable
How do cholesterol interact with sphingolipids?
Sphingolipids have longer, straighter chains, cholesterol reduces packing density and keeps membrane fluid
Where are cholesterol enriched sphingolipids found?
Membrane invaginations (Caeolae and clathrin-coated pits)
What is cholesterol an important starting molecule for?
Bile salts
Vitamin D
Steroids (cortisol and aldosterone)
Sex hormones (progesterone, oestrogen and testosterone)
Where are fat droplets originating from?
Endoplasmic reticulum, bound in monolayer (contents hydrophobic)
What are glycolipids based on?
Ceramide
What glycolipid is the receptor for the cholera toxin?
GM1 ganglioside
What do glycolipids do?
Protect from the environment, cell to cell contact, important in lipid raft generation function
What membrane proteins bind sugars and contain glycolipids?
Lectins
Why are hepatocytes enriched with phsophatidylcholine?
Secrete PC into the bile
Why is the ER low in cholesterol and high in glycerophospholipids?
Makes it more fluid for protein insertion
Myelin is enriched in what type of lipid?
Glycolipids- insulate nerve axon
What are some limitations to the fluid mosaic model?
- Some proteins are anchored or tied to extracellular/intracellular matrix/cytoskeleton
Lipids can be signalling molecules
Lipids modules membrane protein activity
What % of coding capactiy of the human genome is for membrane proteins?
26%
What % drug targets are for membrane proteins?
60%
Name a membrane channel.
Channel CFTR (chloride channel. Mutations lead to cystic fibrosis)
Name a transporter protein.
Transporter ABCB1 (drug efflex plump, causes multidrug resistance)
Name an adherent gap junction between cochlear cells.
Connexin 26
Name a receptor.
Receptors FGFR3 _FGF
What does FGFR3 + FGF do?
Changes gene expression, decreased poliferation of bone cells
Name a membrane enzyme
Phospholipase C
How is glucose uptaken into a cell?
SGLT1 symporter
Na+ driven glucose symport
How is cellular sodium kept low in intestinal epithelial cells?
Na+K+ ATPase (primary active pump) pumps out 3 sodium and in 1 pottasium ion
What protein facilitates glucose diffusion into the extracellular fluid?
GLUT2
What three active transporters were identified to cause progressive familiar intrahepatic cholestasis?
ATP8B1
ABCB4
ABCB11
What is a dominant disease caused by deficiency in receptor-mediated endocytosis?
Familiar hypercholesterolaemia
What domain is deleted in familial hypercholesterolameia?
Clathrin interaction domain, affects 1 in 500 UK popn.
What does CFTR do?
Releases Cl- to induce flow of Na+ and water to reduce viscocity of surface mucous
What drug helps as a chemical chaperone to help delta F508 fold to treat CF?
Lumacaftor
What is Ivacaftor an example of?
A potentiator- increases ability of channel to open for G551D patients
