Molecular Cell Biology Flashcards
What do biomembranes do?
Form boundary around cells, form compartments within cells, allow concentration gradients to be established, place of communication and transport between cells, flexible and selectively permeable.
What happens in Alzheimer’s disease?
Dysregulation of membrane proteins.
What happens in Menkes disease?
X-linked lethal disorder, copper-transporting ATPase is defective.
What happens in Wilson’s disease?
Toxic accumulation of copper by failure to excrete copper from the liver into bile.
What are lipids?
A major class of biomolecules that includes fatty acids, triglycerides, phospholipids and cholesterol.
What are lipids used for?
Metabolism, energy storage and cell signalling.
Describe the phospholipid structure.
Composed of phosphoglycerides. Head is charged. Glycerol backbone. 2 hydroxyl chains have fatty acid chains attached another hydroxyl is phosphorylated. Phosphate group also linked to small polar alcohol head groups
Describe sphingolipids.
Contain sphingosine instead of glycerol. Make sphingomyelins. Most common choline polar group. Enriched in the myelin sheath.
What’s the liquid crystalline phase?
Lipids within biomembrane contain fatty acids that can move. Double bonds prevent very close packing of acyl chains - acyl chains are mobile.
Name some membrane proteins.
Integral membrane proteins.
Peripheral proteins.
Transmembrane proteins.
How does lipid signalling work?
By receptors, G coupled receptors, nuclear receptors. Roles as precursors of signalling molecules and cellular messengers.
What is passive diffusion?
No energy needed. From high conc to low conc.
What is simple diffusion?
Small non-polar molecules and uncharged molecules.
What is facilitated diffusion?
Larger polar molecules that need transporters.
What are ATPases?
An enzyme that catalyses the hydrolysis of ATP. Some are integral membrane proteins and move solutes across the membrane against conc gradient = transmembrane ATPases.
What is primary active transport?
Directly uses the chemical energy to move molecules through the membrane. Na/K pump is one, 3 Na out and 2 K in. The energy needed to pump against conc and electrochemical gradient.
What is secondary active transport?
Molecules moved through the membrane as a direct result of diffusion of another substance. Sodium-calcium antiporter, transport of 2 different molecules in different directions simultaneously. ATP not used directly energy comes from a gradient that was created by primary active transport that uses ATP.
What is ABC transporter?
ATP-binding cassette transporter - ATP dependent pumps - transmembrane protein. Hydrolyse ATP to drive transport across the membrane. Also participate in the movement of drugs and their metabolites across cell surface and organelle membranes.
