CSB351Y1 Lecture Notes - Lecture 5: Phosphatidylcholine, Sphingomyelin, Phosphatidylserine

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grayhedgehog733

4 Apr 2011

School

UTSG

Department

Cell and Systems Biology

Course

CSB351Y1

Professor

Mounir Abou Haidar

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Lipids not synthesized by virus: simply taking a piece of membrane itself. Some viruses (paramyxoviruses e. g. measles) contain lipids and glycoproteins--> components form viral envelopes (glycoproteins form the spikes, which project from the virus particle. ) Enveloped viruses have lipids--> lipids are soluble to organic solvents (i. e. oil, alcohol), therefore, if wash hands with 70% alcohol, destroy viruses with envelopes. If destroy envelopes: virus dead--> glycoproteins on envelope is how virus attaches to the cell. But some viruses (hepatits a): no envelopes--> alcohol doesn"t affect them. Lipid containing viruses: usually released from infected cells by a budding process. Similarities between cell membrane and viral envelope--> viral membrane mostly originate from cell membrane. Viral lipids same as cell lipids: cholesterol, phospholipids (sphingomyelin, phosphatidylcholine, phosphatidylserine, etc)--> found in. Budding process: once you put sugar on protein --> = putting zip code on letter, straight to membrane of the cell. Cells have machinery that put sugar on protein, virus knows glycosylation signal.

Related Questions

The flu virus has a lipid envelope around its protein capsid(shell). The cold virus does not have an envelope. Which of thesetwo viruses is most quickly controlled by alcohol-based handsanitizers? Explain.

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What is the relationship of:

- glycerol and phospholipids

- heads and tail cartoon and membrane phospholipids

- condensation reactions and synthesis of membrane phospholipids

- membrane fluidity and cell function

- length of fatty acid chains in phospholipids and membrane fluidity

- saturation of fatty acid chains in phospholipids and membrane fluidity

- amphipathic nature of cholesterol and its ability to interact with membrane phospholipids

- lipid rafts and membrane fluidity

- ether linkages in phospholipids and response to acidic conditions

- ester linkages in phospholipids and response to acidic conditions

- strong detergent such as SDS and membrane proteins

- weak detergent such as Triton X-100 and membrane proteins

- detergents and their effect on lipid bilayers

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Cholesterol is transported in the bloodstream in lipoproteinparticles. There are several classes of lipoprotein particles, butone of the most important classes is called Low-densitylipoproteins (LDL). LDL particles are composed of a single moleculeof a large protein called apolipoprotein, as well as thousands ofcholesterols molecules and phospholipids. Part of theapolipoprotein forms the surface of the particles and faces theaqueous phase, while other parts face the hydrophobic interior ofthe particle where they interact with cholesterol and thehydrophobic tails of the phospholipids. When cells need additionalcholesterol, they produce a receptor protein on the surface oftheir plasma membrane that binds to the apolipoprotein andinitiates the uptake of LDL particles into the cell via a processcalled endocytosis.

1. What is the likely reason that LDL particles are used totransport cholesterol in the blood stream?

a. Cholesterol in LDL particles easily inserts into lipidbilayers

b. Cholesterol id largely insoluble in aqueous solutions

c. Cholesterol is synthesized within LDL particles

d. LDL particles can form lipid rafts in the lipid bilayer

2. What is the most likely location of phospholipids in LDLparticles?

a. Bound to the hydrophilic domain of apolipoprotein

b. In the lipid bilayer that surrounds LDL particles

c. On the surface interacting with the aqueous environment aswell as interacting with the hydrophobic core of the particle

d. Within the hydrophobic core of the particle

3. What best describes the class of protein that apolipoproteinbelongs to?

a. Amphipathic proteins

b. Cell surface proteins

c. Membrane associated protein

d. Multipass membrane proteins

4. What kind of molecule on the surface of the cell would bemost likely to serve as a receptor for LDL particles?

a. a cholesterol binding protein

b. a glycolipid

c. a phospholipid

d. trans membrane protein

5. What conditions would be most likely to trigger increaseduptake of LDL particles by cells?

a. increased glycolipid synthesis

b. increased plasma membrane growth

c. increased protein secretion

d. increase protein synthesis

CSB351Y1 Lecture Notes - Lecture 5: Phosphatidylcholine, Sphingomyelin, Phosphatidylserine

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