BMSC 200 Module 9 Exam Questions
and Answers
membrane composition - ANSWER-- Membranes are primarily composed of lipids
and proteins.
- More active membranes have a higher ratio of protein to lipid.
fluid mosaic model - ANSWER-- Lipids and proteins freely diffuse in the plane of the
membrane.
- Movement is restricted and lateral movement is very rapid.
transbilayer movement - ANSWER-- Requires polar head group catalysis to pass
through a hydrophobic environment.
- Translocation of lipids from 1 side to the other is catalyzed by enzymes called
flippases.
- Flip flop (uncatalyzed transverse) is very SLOW.
membrane fluidity - ANSWER-- Membranes undergo temp- dependent phase
transition.
- Below the phase transition, membranes are too solid.
- Above the phase transition, membranes are too fluid.
- At the phase transition, hydrocarbons are partially ordered but lateral diffusion is
possible.
composition and distribution - ANSWER-- Varies across species and cell types.
- Includes dynamic changes to comp and/or positioning to regulate biological events.
Ex: in phosphatidylserine, if they sense that their about to die, they "commit suicide"
(apoptosis) and they remove themselves out.
lipid rafts - ANSWER-- Arise from spontaneous association of lipid molecules where
the hydrocarbon tails are of similar length.
- Sphingolipids with longer tails, form clusters that exclude glycerophospholipids.
- The lipid rafts can split off or fuse together as well.
membrane proteins - ANSWER-- Active roles are performed by receptors and
transporters.
- There are 3 types: peripheral (c&d), lipid- anchored (e), and integral membrane
proteins (a&b).
peripheral proteins - ANSWER-- Associate through electrostatic or hydrogen bonding
interactions.
- Docks to membrane lipids or proteins.
- Usually in cytosol or extracellular space.
and Answers
membrane composition - ANSWER-- Membranes are primarily composed of lipids
and proteins.
- More active membranes have a higher ratio of protein to lipid.
fluid mosaic model - ANSWER-- Lipids and proteins freely diffuse in the plane of the
membrane.
- Movement is restricted and lateral movement is very rapid.
transbilayer movement - ANSWER-- Requires polar head group catalysis to pass
through a hydrophobic environment.
- Translocation of lipids from 1 side to the other is catalyzed by enzymes called
flippases.
- Flip flop (uncatalyzed transverse) is very SLOW.
membrane fluidity - ANSWER-- Membranes undergo temp- dependent phase
transition.
- Below the phase transition, membranes are too solid.
- Above the phase transition, membranes are too fluid.
- At the phase transition, hydrocarbons are partially ordered but lateral diffusion is
possible.
composition and distribution - ANSWER-- Varies across species and cell types.
- Includes dynamic changes to comp and/or positioning to regulate biological events.
Ex: in phosphatidylserine, if they sense that their about to die, they "commit suicide"
(apoptosis) and they remove themselves out.
lipid rafts - ANSWER-- Arise from spontaneous association of lipid molecules where
the hydrocarbon tails are of similar length.
- Sphingolipids with longer tails, form clusters that exclude glycerophospholipids.
- The lipid rafts can split off or fuse together as well.
membrane proteins - ANSWER-- Active roles are performed by receptors and
transporters.
- There are 3 types: peripheral (c&d), lipid- anchored (e), and integral membrane
proteins (a&b).
peripheral proteins - ANSWER-- Associate through electrostatic or hydrogen bonding
interactions.
- Docks to membrane lipids or proteins.
- Usually in cytosol or extracellular space.
