lipids Flashcards
What is the structural difference between saturated and unsaturated fatty acids?
Unsaturated fatty acids have one or more double bonds, which introduce kinks into the chain.
What is the main lipid component of cellular membranes?
Phospholipids.
What are triacylglycerols composed of?
Glycerol esterified to three fatty acids.
What is the function of glycolipids in membranes?
They are involved in cell recognition and are commonly found in neuronal membranes.
What is the backbone molecule in phospholipids?
Glycerol.
What is sphingomyelin derived from?
Sphingosine and a fatty acid (ceramide) with a phosphocholine head group.
What is the fluid mosaic model?
It describes the membrane as a fluid lipid bilayer with proteins floating within it like islands.
Why are membranes described as asymmetrical?
Different lipids are found on the inner vs outer leaflets of the bilayer.
How do short chain fatty acids affect membrane fluidity?
They increase fluidity by reducing van der Waals interactions.
How does unsaturation in fatty acids affect membrane fluidity?
It introduces kinks, preventing tight packing and increasing fluidity.
How does cholesterol affect membrane fluidity?
It decreases fluidity by ordering lipid tails, especially at physiological temperature.
What is the role of lipid rafts?
They are microdomains that organize signaling molecules and are less fluid, rich in cholesterol and sphingolipids.
What are integral membrane proteins?
Proteins that span or are embedded within the lipid bilayer.
What are anchored proteins?
Proteins covalently attached to a fatty acid chain or glycolipid anchor.
What are peripheral proteins?
Proteins attached via ionic or hydrogen bonds to membrane lipids or other proteins.
Which membrane proteins require detergents for removal?
Integral membrane proteins.
Which enzyme is inhibited by statins?
HMG-CoA reductase.
Why is cholesterol important in membranes?
It stabilises membranes and reduces fluidity.
How does statin therapy influence membrane properties?
By lowering cholesterol synthesis, it can increase membrane fluidity.
Which phospholipid is found on the inner leaflet of the membrane?
Phosphatidylserine (PS).
Which phospholipids are usually found on the outer leaflet?
Phosphatidylcholine (PC) and sphingomyelin (SPH).
What happens if a GPI anchor is lost from a protein?
The protein may be released from the membrane into the extracellular space.
How would a cell maintain fluidity in cold conditions?
Increase unsaturated fatty acid content and reduce cholesterol.
What are phospholipases?
Enzymes that hydrolyse phospholipids at specific bonds.
