Cell membranes Flashcards
What are the two groups of phospholipids found in membranes?
Glycerophospholipids - major
Phosphatidylinositols - minor
What are the the types of glycerophospholipids and where are the located?
Phosphatidylcholines (PC) - mainly in outer leaflet
Phosphatidylserines (PS) - exclusively in inner leaflet
Phosphatidylethanolamines (PE) - mainly in inner leaflet
Where are phosphatidylinositols located in the membrane?
Mainly in inner leaflet
What are sphingolipids derived from and where are they located?
Ceramide
Mainly in outer leaflet
What are glycolipids and what is there function in membranes?
Most from ceramides
Minor, but essential
Exclusive to outer leaflet
What is the function of cholesterol in the plasma membrane?
Maintain structural integrity of membrane
What are the main methods of transportation across the plasma membrane?
Osmosis
Simple diffusion
Facilitated transport
Active transport
Exocytosis
Endocytosis
Transcytosis
What is osmosis?
Uses aquaporins to transport water
What is facilitated diffusion?
Uses transporters to move large, charged, or hydrophilic molecules down their concentration gradient
How does active transport differ from passive transport, and what are the two types?
Uses energy
Primary
Secondary
What is primary active transport and its main example?
Pumps against concentration/electrochemical gradient directly using ATP
Na/K ATPase
What is secondary active transport?
Uses energy from moving one molecule down its concentration gradient to move another molecule against its gradient
What is an example of secondary active transport and how does it?
Na/Glucose SGLT1 - symport
Na moved down its gradient provides energy to move glucose into the cell against its gradient
What are ion channels?
Transmembrane proteins that form channel selective to a specific ion - often gated
What are the three major glasses of ion channel gates?
Voltage
Ligand
Mechanically
