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23 Cards in this Set

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List some (7) common membrane lipids.
•phospholipids - most abundant membrane lipids
•phosphatidylcholine - most common phospholipids
•phosphatidylserine - negatively charged
•phosphatidylethanolamine
•sphingomyelin
•cholesterol
•glycolipids
List some (4) attributes of mobile lipids.
• rotate
• diffuse laterally
• flex fatty acid tails
• flip-flop from one side to the other (rare event)
What is membrane flexibility?
Flexibility - ability of the membrane to bend and withstand other deformations.
What is the purpose for always having Phosphatidylinositol in the cytosolic half of the lipid bilayer?
Because of its role in cell signaling.
What is the name of the carbohydrate coat surrounding the lipid bilayer?
Glycocalyx.
List some (4) functions of membrane proteins.
•Transport of molecules across bilayer
•Anchoring
•Receptors
•Enzymes
Give an example of a single-pass transmembrane protein.
Receptor.
Give an example of a multi-pass transmembrane protein.
Aqueous pores.

*Cross the bilayer as curved beta sheets - form a beta barrel with aqueous interior (e.g. porins in mitochondrial membrane and in bacteria).
Name the general solvent that can be used to disrupt a bilayer.
Detergent.
T/F?
"Protein-attached proteins" are attached through covalent interactions with transmembrane proteins
False. Non-covalent.
Name a method used to remove protein attached proteins.
Salt wash or enzymes.
T/F?
Lipid-linked proteins are attached through covalent bonds with membrane lipids.
True.
What is one of the best studied transmembrane proteins?
Bacteriorhodopsin.
*A light-activated proton pump extracted from Halobacterium halobium.
What is a chromophore?
A chromophore is a part (or moiety) of a molecule responsible for detecting color.
T/F?
Phosphatidyl serine is concentrated in the inner (cytoplasmic) half of the bilayer.
True.
T/F?
Phosphatidyl choline is concentrated in the outer (extracellular) half of the bilayer.
True.
T/F?
Glycolipids are concentrated on the intracellular surface of the bilayer.
False: Extracellular.
What is the cell cortex?
The plasma membrane is supported by a scaffolding composed of a network of filamentous proteins (the cell cortex) attached to the cytoplasmic face of the membrane.

Functions:
•physically supports and stabilizes the membrane
•determines the shape of the cell
What is the RBC cortex composed of?
*Spectrin (240 & 220 kd fibrillar protein) forms 3-dimensional network associated with the inner surface of the plasma membrane
*Ankyrin (210 kd protein) attaches spectrin to the membrane
*Actin (43 kd protein) forms filaments attached to spectrin via an attachment protein
What are proteoglycans?
Glycoproteins that are heavily glycosylated.
What are lectins?
Lectins are sugar-binding proteins that are highly specific for their sugar moieties.
What are Selectins?
Selectins are a family of cell adhesion molecules (or CAMs).
What is FRAP?
Fluorescence recovery after photo-bleaching (FRAP):
1. Labeling of membrane proteins with a fluorescent dye
2. Bleaching of label in a spot with laser light
3. Diffusion of unbleached label into the area
4. Recovery of fluorescence