Term
| What are the 4 major components of the lipid bilayer? |
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Definition
1. Phospholipids
2. Cholesterol
3. glycolipids
4. proteins |
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Term
| What phospholipid tail structure promotes membrane fluidity and how? |
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Definition
Cis double bonds
1. Allow rotation
2. Reduce van der Waal forces |
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Term
| What role does cholesterol provide and how does it do this? |
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Definition
Reduces membrane fluidity and as such permeability
1. Polar head interacts with polar head of phospholipid
2. Nonpolar tail interacts with nonpolar phospholipid tail
3. Rigid steroid ring structure in between the head and tail provides a stiffened region in the membrane |
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Term
| What is lateral mobility in membranes and what factors govern it? |
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Definition
The ability or proteins to migrate laterally across the surface of a membrane.
Controlled by:
1. Size of molecule
2. Interactions with other molecules
3. Temperature
4. Lipid composition (ex. cholesterol presence) |
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Term
| What are the 4 types of membrane proteins |
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Definition
1. Transmembrane span the whole membrane)
2. Membrane-associated (only interact with one side of the membrane)
3. Lipid-linked (proteins bound to membrane lipids)
4. Protein attached (proteins attached to other membrane proteins) |
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Term
| Describe how membrane proteins form pores? |
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Definition
| alpha-helixes in transmembrane proteins combine to form pores in the membrane for molecules to pass into and out of |
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Term
| What are lipid rafts and how do they differ from the surrounding lipids in the membrane? |
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Definition
Lipid rafts are specialized membrane structures that compartmentalize cellular processes by serving as organizing centers for the assembly of signaling molecules, influencing membrane fluidity and membrane protein trafficking.
They have higher concentrations of cholesterol, glycolipids, and membrane proteins then the normal lipid bilayer. They also contain a glycocalyx. |
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Term
| What is the glycocalyx and what role does it play? |
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Definition
Glycocalyx is a glycoprotein found on the extracellular surface of cells.
Everyone's is unique, so it plays a role in protection by identifying foreign or diseased cells. If also plays a role in cell adhesion. |
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