FINAL EXAM CHAPTER 12 Membrane Structure and Function Flashcards
What are the structures and properties of membranes?
-Sheetlike structures, two molecule thick, that form closed boundaries
-non-covalent assemblies
-Asymmetric in that the outer surface is always different from the inner surface
-fluid structures
-Electrically polarized such that the inside is negative
What are membrane lipids and what do they form?
-They are small amphipathic molecules that form closed bimolecular sheets that prevent the movement of polar or charged molecules
Why do we need proteins in membranes?
- because they help polar things across the membrane but non polar are allowed to pass too.
What determines the membrane permeability?
- Solubility
- ions
- polar molecules
- Hydrophobicity
- if there are water molecules or not
What is the role of Cholesterol in membrane fluidity
- They help maintain proper membrane fluidity in membranes in animals
The temperature at which a membrane transitions from being highly ordered to very fluid is called?
Melting Temperature
What is the melting temperature dependent on?
-Length of the fatty acids in the membrane lipid
-Degree of cis unsaturation
What are the three proteins that associate with the lipid bilayer ?
-Integral Protein
-Peripheral membrane protein
-Anchored membrane protein
What are integral proteins?
-Proteins that are embedded in the hydrocarbon core of the membrane
What are Peripheral Membrane proteins ?
-Proteins that are bound to the polar head groups of membrane lipids or to the exposed surfaces of integral membrane proteins
What are Anchored membrane proteins?
-Proteins that are associated with membranes by attachment to a hydrophobic moiety that is inserted into the membrane
What is lateral diffusion ?
This is when a membrane component is attached to a fluorescent molecule and it slowly moves down and the mobility of the it depends on how rapidly the bleached area recovers fluorescence
What does lateral diffusion depend on?
-Whether they are attached to other cellular or extracellular components
What is transverse diffusion ?
- This is when lipids rapidly diffuse laterally in membranes .
What is transverse diffusion dependent on?
-The assistance of enzymes or without it it is very slow
What is passive transport?
-It is when a molecule moves down its concentration gradient through a transport protein
What is active transport?
Its when protein pumps use energy to move a molecule against its concentration gradient
What are symporters?
This powers the transport of a molecule against its concentration gradient by coupling the movement to the movement of another molecule down its concentration gradient, with both molecules moving in the same direction
What are Antiporters?
One concentration gradient to power the formation of another, but the molecules move in opposite direction
What is the Na/K pump?
This uses the energy of ATP hydrolysis to simultaneously pump three NA+ ions out of the cell and two K+ ions into the cell against their concentration gradients.
What are ion channels?
Passive transport systems that allow specific and rapid transport of ions down their concentration gradients.
THIS WILL BE ON THE EXAM
How can the K+ channel be selective?
This is because potassium carries water and therefore larger ions are not transported because they are too big to enter the channel. IN order for Potassium to go through the 3 angstrom channel it has to lose the water.
