Structural lipids Flashcards
What are the 5 types of structural lipids?
Glycerophospholipids Galactolipids/sulfolipids Archaeal tetraether lipids Sphingolipids Sterols
What two general categories are structural lipids divided into?
Phospholipids and glycolipids
What is the polar head group of phospholipids? Which types of structural lipids are phospholipids?
Phosphate group. Glycerophospholipids and some sphingolipids
What is the polar head group of glycolipids? Which types of structural lipids are glycolipids?
Sugar group. Includes galactolipids, sulfolipids and some sphingolipids
How are archaeal ether lipids structured?
Contains 2 polar phosphates on the end connected by hydrophobic chains, linked with ether linkages
What is the structure of glycerophospholipids?
Two fatty acids attached to a glycerol. The third position of the the glycerol has a phosphate attached. The phosphate has a polar head attached to it
What are the 7 possibilities for the polar head group on a glycerophospholipid?
Hydrogen Ethanolamine Choline Serine Glycerol Myo-inositol 4,5-bisphosphate Phosphatidylglycerol
What is a glycerophospholipid with a hydrogen as its polar head group called? Where is this found? What is the net charge of the lipid?
Phosphatidic acid. Not found in membranes, but has other uses. Net charge of -2
What is a glycerophospholipid with an ethanolamine as its polar head group called? What is the net charge of the lipid?
Phosphatidylethanolamine. Net charge of 0
What is a glycerophospholipid with a choline as its polar head group called? Where is it found? What is the net charge of the lipid?
Phosphatidylcholine. It is very common in the outer leaflet of membranes. Net charge of 0
What is a glycerophospholipid with a serine as its polar head group called? What is the net charge of the lipid?
Phosphatidylserine. Net charge of -1
What is a glycerophospholipid with a myo-inositol 4,5-bisphosphate as its polar head group called? What is the net charge of the lipid?
Phosphatidylinositol-4,5-bisphosphate. Net charge of -4
What is a glycerophospholipid with a glycerol as its polar head group called? What is the net charge of the lipid?
Phosphatidylglycerol. Net charge of -1
What is a glycerophospholipid with a phosphatidylglycerol as its polar head group called? Where is it found? What is the net charge of the lipid?
Cardiolipin (is a double phospholipid). Found in the outer mitochondrial membrane and in bacterial membranes. Net charge is -2
Where are galactolipids found?
In plants: thylakoid membranes
What is the most abundant membrane lipid on earth?
Galactolipids
Why is having galactolipids in their thylakoid membranes instead of phospholipids an advantage?
Phosphate is a limiting nutrient in the soil and having galactolipids instead of phospholipids means that the plants can use less phosphate
What is the polar head group in galactolipids?
Galactose
What is the structure of archaeal membrane lipids? What is it called?
One polar carbohydrate end and one glycerol phosphate end connected by 2 branched hydrophobic diphytanyl chains. The glycerol is attached by an ether linkage. Called GDGT (glycerol dialkyl glycerol tetraether)
Why do the membrane lipids of Archaea help them tolerate extreme environments?
The tetraether lipids are interspersed in the membrane, which stabilizes it. The ether linkages are less susceptible to hydrolysis
What is the structure of sphingolipids?
A sphingosine backbone (instead of glycerol), a polar head group, a fatty acid that is attached to the sphingosine with an amide linkage
What are 4 possible head groups in sphingolipids?
Hydrogen
Phosphocholine
Glucose
Complex oligosaccharides
What is a sphingolipid with a hydrogen as its head group called?
Ceramide
What is a sphingolipid with a phosphocholine as its head group called? Where is it found?
Sphingomyelin. Found in the myelin sheaths on neurons
What is a sphingolipid with a glucose as its head group called? Where is it found?
Glycolipids. Found in the outer leaflet of membranes
What is a sphingolipid with complex oligosaccharides as its head group called? Where is it found?
Gangliosides. Found on outer leaflet of membranes, and can have a wide variety of structures by attaching different sugars to it
What are the functions of gangliosides?
Cellular recognition, cell adhesion, change during development
How are gangliosides involved in diseases?
Tumours have unique gangliosides, act as receptors for pathogens and their toxins, Guillain-Barre syndrome, Tay-Sachs
What is Guillain-Barre syndrome?
An autoimmune reaction to neuron gangliosides that causes temporary acute paralysis
What happens if gangliosides can’t get broken down?
Causes lysosomal storage diseases like Tay-Sachs that are usually lethal
What do sterols do?
Structural components of membranes
What is the structure of sterols?
They have a nucleus that varies between sterols, but is rigid and planar in cholesterol. The polar head group is just a hydroxyl
What is the structure of cholesterol?
Rigid and planar nucleus that is the same length as the average phospholipid
Why is cholesterol so important in animal cell membranes?
Acts as a membrane fluidity buffer. Prevents the phospholipids from packing too tightly at low temperatures and becoming too fluid at high temperatures
