Chapter 6 - Cell Membranes Flashcards
What does amphipathic mean?
Having both hydrophobic and hydrophilic parts in the same molecule.
Membrane lipids are amphipathic.
How many layers of lipids form a membrane?
Two layers. Lipid bilayer.
Which way do the ends of the lipids point towards?
Hydrophobic ends point inward towards the center of the membrane. Hydrophilic ends points outside towards the water.
What is the most common kind of molecule in lipid bilayer membranes?
Phospholipids
What is self assembly?
Lipid bilayers self assemble because of the physics of amphipathic molecules. Like stirred up in water then self assemble.
Besides phospholipids whats another molecule in a lipid membrane?
Cholesterol.
When does the melting point increase / resist heat?
With the length of the hydrocarbon part and fewer double bonds.
When does the melting point decrease / resist cold?
Decreases with the number of double bonds and shorter fatty acids.
What makes membranes less flexible?
Longer fatty acid chains.
Cholesterol & temperatures
At warm temperatures, cholesterol stabilizes membranes. At cold temperatures, cholesterol preserves fluidity.
What is permeability?
How substances pass through cell membranes.
Cell membranes are:
Selectively permeable.
Can ions and large polar molecules go through the membrane?
No.
Name 3 things that can leak through the membrane.
CO2, O2, Benzene, H2O, Ethanol
What types of molecules can go through the membrane?
Small molecules.
