Cell membranes are fluid and thus proteins can diffuse laterally within the lipi
ID: 132099 • Letter: C
Question
Cell membranes are fluid and thus proteins can diffuse laterally within the lipid bilayer most likely accompanied by specific lipids. This association of protein and lipids is called
a) lipid graft.
b) phase diagram.
c) lipid raft.
d) protein raft.
------
Porin proteins form large, barrel-like channels in the membrane. Which of the following is not true about these channels?
a) They are made primarily of a-helices.
b)They are made primarily of b-pleated sheets.
c)Proteins cannot form narrow channels.
d)They have alternating hydrophobic and hydrophilic amino acids.
----------
You have a protein that is easily extracted from a cell membrane preparation, without any associated lipids, by washing with a buffer containing a salt (e.g. 2M NaBr) without the need to treat the membrane with detergents. What type of protein do you have?
a) Peripheral (extrinsic)
b) A protein covalently anchored to membrane fatty acids
c) Transmembrane
d) None of the above
Explanation / Answer
ANSWER 1
LIPID RAFT is correct answer.
Lipid rafts are combination of lipds and proteins. They form a functional structure by combinig lipds and proteins. They may be involved in cell signalling, can form receptor for extracellular signals etc.
ANSWER 2
They are made of a-helices is the correct answer.
Porins are made up of b-pleated sheets.
ANSWER 3
Peripheral (extrinsic) is correct answer.
Intrinsic proteins are not easy to extract and on extraction of intrinsic protein lipd bilayer is also dirupted. While extrinsic proteins can be easily isloated from plasma membrane because they are not inserted in the lipd bilayer and their extraction donot affect lipd bilayer.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.