Module 3: The Structure and Function of the Plasma Membrane Flashcards
What is plasma membrane?
- It i the outer boundary of the cell that separates it from the world. It is a thin, fragile structure.
- Need electron microscope to examine.
Describe the plasma membrane structure?
- Found to be mostly composed of oil.
- The lipid bilayer accounted for the 2:1 ratio of lipid to cell surface area.
What is the myelin sheath?
It acts as the electrical insulation for the nerve cell.
What are membrane lipids?
They are amphipathic which contain both hydrophilic and hydrophobic regions.
Describe phospholipids?
They are lipids with a phosphate group.
Describe phosphoglycerides?
Phospholipids built on a glycerol backbone.
Describe Shingolipids?
Derivatives of sphingosine, an
amino alcohol that contains a
long hydrocarbon chain.
What are cermides?
- Are the basic structural units of all sphingolipids.
- A ceramide consist of sphingosine linked to a fatty acid (R) by its amino group.
Function of the lipid bilayer?
Helps maintain the proper internal composition of a cell.
Function of liposomes?
They are synthetic vesicles that act as vehicles to deliver drugs, DNA, RNA within the body.
How are oligosaccharides attached to amino acids?
By two types of linkages: N-linkages and O-linkages.
Function of glycolipid carbohydrates of the red blood cell?
Determines whether a person’s blood type is A, B, AB, or O.
Types of blood types:
A: Enzyme adds N-acetylgalactosamine to the end of the chain.
B: Enzyme adds galactose to the chain terminus.
AB: Both enzymes present.
O: Lack enzymes capable of
attaching either terminal sugar.
Function of integral membrane proteins?
They function as receptors that bind ligands, channels or transporters to move ions/solute across the membrane.
What forces drive integral membrane proteins?
They are driven by van der waals forces between amino acids and lipids.
What is peripheral membrane proteins?
- Peripheral proteins associate with the membrane by weak electrostatic bonds.
- Have a dynamic relationship with the membrane, being recruited or released as needed.
What are lipid-anchored membrane proteins?
They are covalently bonded to a lipid group that reside within the membrane.
What are the two types of lipid-anchor and the surface they are exposed to?
- Proteins located on the external face linked to the membrane via a GPI-porteins.
- Proteins located on the cytoplasmic side of the plasma membrane and anchored by one more long hydrocarbon chain in the inner membrane.
What describes the physical state of membrane lipids?
By its fluidity or viscosity.
How do cells respond to fluctuating temperatures?
By altering phospholipid composition.
What catalyzes desaturation?
It is catalyzed by desaturases.
Function of lipid rafts:
They provide a favorable environment for cell-surface receptors.
What cell fusion?
It is a technique whereby two different types of cells, or cells
from two different species, can be fused to produce one cell.
