Cell Bio Exam 2 Lecture 6 Flashcards
Water is important for its role in ordering the
________ ________ that form
________ ________
amphipathic phospholipids, membrane bilayers
Formation of _______
is energetically favored in aqueous environments
closed vesicles
Cholesterol is an amphipathic molecule T or F
True
Two of the major components of the lipid bilayer
Phospholipids, cholesterol
What are the 3 major phospholipds?
Phosphatidylcholine
Phosphatidylethanolamine
Phosphatidylserine
Which of the following movement(s) occurs least frequently for phospholipids in membrane bilayers:
Lateral movements within the plane of the same bilayer
Flexion along their long axis
Rotation about their long axis
Movement into the other leaflet of the bilayer
Movement into the other leaflet of the bilayer
Dynamics of phospholipids
Rotation, lateral diffusion, Flip-flop (rarely occurs)
Proteins that aid the movement of phospholipids from one leaflet of a membrane bilayer to another are known as:
Flippases
Membrane fluidity depends on
composition and length of the phospholipid hydrocarbon tails
An increase in cholesterol content will tend to make membranes:
Less permeable and less flexible
Cholesterol is also important to the formation of
lipid rafts
Cholesterol forming lipid rafts are….
enriched in signaling proteins whose diffusion is more limited
Membranes are more fluid in nature when hydrocarbon tails are ___ and ___.
unsaturated, short
Of the following choices regarding hydrocarbon tails, which would be the least fluid?
no double bonds and 16 carbons long
no double bonds and 20 carbons long
one double bond and 16 carbons long
one double bond and 20 carbons long
None of the above – only cholesterol determines fluidity
no double bonds and 20 carbons long
Where are membrane phospholipids first synthesized and inserted into membranes?
The cytosolic surface of the ER
