Lecture 2/ Chapter 2 Flashcards Preview

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Flashcards in Lecture 2/ Chapter 2 Deck (40):

What is the function of lipid rafts?

They concentrate the ligand-receptor complexes into coated pit regions of the Plasma Membrane for RME (receptor mediated endocytosis) and are important for bringing together the components of signal transduction pathways


Why are lipids fluid?

Because of the flexibility of acyl chains, which are oriented toward the hydrophobic part of the bilayer. Head groups are oriented towards the aqueous phases of the cell.


Temperature increases or decreases membrane fluidity?



Increasing lipid chain length increases or decreases fluidity?



Describe how degree of unsaturation affected membrane fluidity?

Less saturation increases fluidity-- think increased # of kinks--> increases distance b/t the fatty acids and results in increased fluidity/flexibility


Describe how cholesterol affects fluidity?

It could increase or decrease fluidity; It depends upon other lipids present and temperature. Usually it will decrease fluidity (more rigid)


Describe the mechanism for Walking Pneumonia

Mycoplasma bacteria enters lungs-- travels to resp cilia cells and attaches to the base of the cilia; there it extracts the cholesterol from the plasma membrane surrounding the cilia, which causes the membrane to become very fluid. The cilia can't beat anymore-- mucous accumulates and provides a rich medium in which mycoplasma propagate. Secondary bacterial pneumonia often sets in


Name 4 types of transport across the plasma membrane

1- Passive -- i.e. ionic diffusion
2- Coupled transport- i.e. ionic exchange
3- Active transport- i.e. Na+ exchanger
4- Charged pores- i.e. channels and gates


Describe pathogenesis of HIV

HIV has a viral protein coat that is recognized by CD4 receptors on T-cells, macrophages, and other cell types. This causes a rapid fusion of the viral coat lipids w/ the host cell. Subsequently, the the viral capsid and nucleoproteins enter the host cell cytoplasm where replication of the viral genome ensues. The viral glycoprotein that is recognized by CD4 is inserted into the cell membrane-- now the infected cell can fuse w/ other CD4+ cells, even w/o the virus.


What is another example of a virus that utilizes fusogenic properties of phospholipids as a means of infecting cells?



What are the three components of phospholipids?

1) polar head group
2) phosphate group
3) glycerol group


If a cell cannot dispose of sphingolipids properly, what kind of disease may occur?

Lysosomal storage disease


Tay- Sachs Disease
1) Describe disease type
2) Describe mechanism
3) Describe potential symptoms/outcomes

1) Lysosomal storage disease
2) Enzyme deficiency of hexosaminidase A-- disrupts sphingolipid breakdown; GM2 ganglioside builds up.
3) Mental retardation, blindness, and early death


Fabry's Disease
1) Describe disease type
2) Describe mechanism
3) Describe symptoms
4) Treatment

Lysosomal storage disease
2) An alpha Galactosidase A deficiency results in the build up of ceramide in lysosomes
3) Rash on inner lip/tongue and kidney failure
4) Enzyme therapy


Gaucher's Disease

A type of lysosomal storage disease that is treated w/ enzyme therapy


Niemann-Pick Disease and GM1 Gangliosidosis are types of ?

Lysosomal storage diseases


What is the purpose of an eichosanoid?

They are made up from the phospholipids in the plasma membrane and are precursors for major regulatory functions in the cell


What are the three classes of eichosanoids?



Prostaglandins-- function? location?

Function: vasodilation, vasoconstriction, uterine contraction. Mast cells, kidneys, spleen and heart


Thromboxanes-- function?

induce platelet aggregation and function in clotting and vasoconstriction


Leukotrienes-- function? location

Increase WBC motility and play and role in asthma and anaphylaxis. Found in mast cells, leukocytes, basophils and epithelium


Integral Proteins

Embedded in PM and can only be removed w/ a detergent


What is the structure of integral proteins?

They are three domain proteins w/ extracellular , membrane spanning, and intracellular components-- the extracellular domain is glycosylated.


How many times may an integral protein span the membrane?

Once or more-- examples include glycophorin (1) and Band 3 Protein (14 times)


Structural rigidity for many cells is determined by interactions between?

The plasma membrane proteins and cytoskeletal proteins-- example is erythrocyte


Hereditary Spherocytosis
1) Describe mechanism
2) Describe genetics
3) Describe symptoms/outcomes

1) There is a defect in the linkage complex or spectrum protein (the flexibility and strength of the RBC is due to connection of integral membrane proteins w/ spectrum cables)
2) Autosomal dominant genetic disease
3) Misshapen erythrocyte causes splenomegaly bc it can't travel through the splenic sinuses-- splenomegaly and anemia (d/t macrophages attacking RBC in the spleen)


Peripheral proteins
What is association w/ PM
How are they removed?
How does this differ from integral proteins

They are loosely associated. Removed w/ simple treatments such as pH changes. Integral proteins must be removed w/ a detergent d/t more extensive involvement in the PM


Why are glycoproteins important?

They are associated w/ the plasma membrane; they play a role in the recognition of self that is critical to proper immune function-- Blood typing A, B, AB , O



Protozoans that can cause coccidiosis-- found in food/water in developing countries. Bind to cells of the GI tract. Evolved highly specific recognition proteins on their cell that can distinguish b/t the host cells in diff parts of GI tract



Pathogen found in cat feces that has the potential to cause severe birth defect in unborn children-- protozoan binds to certain cells in the body based on the glycoproteins expressed on these cells


What percentage of cell volume is comprised of membranes?



Plasma membrane takes up __% of volume



Chemical composition of membranes-- Protein/ Lipid/ Cab percentages

Less than 50 for protein/ lipids and small amount of carbs


Myelin sheath

18% protein and lipid 79%


Mito inner membrane

76% protein 24% lipid


Classes of membrane lipids in order of abundance

Phospholipids; Sphingolipids; Cholesterol; Eicosanoids


Which leaflet is more fluid?

The outer leaflet-- allow lipid rafts to rapidly concentrate ligand receptor pairs at specific sites on the membrane for internalization


Difference b/t sphingolipid and phospholipids

sphingo are not fusogenic because they are all saturated acyl groups.



enzyme def: Hexosaminidase A
accum subs: GM2 ganglioside
Symptoms: Mental retardation, blindness, early death



Enzyme def : -Galactosidase A
accum subs: Ceramide
Symptoms: Kid failure, skin rash

First treated successfully w/ enzyme replacement therapy