Lecture 2: Membrane Flashcards
Peripheral membrane proteins: What are they and what do they do?
Proteins that sit on the plasma membrane and are not integrated. They have ionic interactions with phospholipids or other proteins.
Integral membrane proteins
Proteins that penetrate the lipid bilayer, but not all the way through.
Transmembrane proteins
Proteins that go all the way through the membrane.
What is the difference between hydrophilic molecules and hydrophobic ones?
Hydrophilic: Charged and polar. Water- mixing molecules.
Hydrophobic: Nonpolar and uncharged. Water-repelling molecules.
When you have little charge seperation do you have a small or large dipole moment?
Small dipole moment.
What allows molecules to interact with each other?
Polarity
What is the plasma membrane? What does it do?
It is a boundary that separates the cell from its surroundings. It enables interactions with surroundings and regulates the flow of materials and signals.
What does it mean to be an amphipathic molecules? How is a phospholipid an amphipathic molecule?
A molecule that contains 2 regions. A phospholipid has a hydrophobic and hydrophilic region.
What are the differences between Saturated and Unsaturated fats?
Saturated fats do not have a double bond and lack kink in chains, making them less fluid.
Unsaturated fats have a double bond, and kinks in chains to limit packing, making them more fluid.
How does cholesterol buffer fluidity?
Cold temp:
Cholesterol can maintain fluidity by preventing tight packing.
Hot temp:
Cholesterol can limit excess fluidity by providing more bonding opportunities for the phospholipids.
How is a typical membrane a fluid mosaic model?
Membranes have proteins that span their layers or on their surface.
What can the proteins in the fluid mosaic model do and not do?
They can move laterally (to modify another protein). They can not flip-flop (to the other layer in the bilayer).
What are the six major functions of membrane proteins?
Transport
Cell to Cell-to-cell recognition
Intracellular joining
- Gap Junctions
- Plasmodesmata
Attachment to the cytoskeleton and ECM
- Integrins binding to ECM proteins
Enzymatic activity & Signal Transduction
- Receptor Tyrosine Kinase Receptors
- GCPR
Having carbohydrates on the cell membrane is important for which of the 6 major functions?
Cell-to-cell recognition
What modifications are made to membrane proteins to dictate function?
Glycoproteins get sugar (glyco) modifications that enable specific binding events.
Receptor Proteins bind soluble factors like ligands.
1. hormones
2. neurotransmitter
3. transmit signals- may be mediated by protein phosphorylation
- Like RTK
