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BiochemistryDVT 1094

Abdul Muhaimin b. Abd Wahab D11 A007

Azwan b. KamarudinD11 B038

Questions• Discuss the effect of abnormalities of cell

membrane fluidity. - Azwan Kamarudin -

• State example of disease and explain how the disease develop.

- Abdul Muhaimin Abd Wahab -

Membrane Fluidity• In biology, the membrane fluidity refers to the viscosity of

the lipid bilayer of a cell membrane.

• The membrane phospholipids incorporate fatty acids of

varying length and saturation. Shorter-chain fatty acids, and

ones with greater unsaturation, are less stiff, less viscous and

have lower melting points.

Factors Effecting Membrane FluidityFactor EffectTemperature Increasing temperature increases fluidity

Saturation Increased unsaturated fatty acid increases fluidity

Cholesterol Increasing the ratio of cholesterol to phospholipid decreases membrane fluidity

Steroids Both increases and decreases (depending on the steroids)

Phospholipid Head group determines the stability of the membrane

Pressure Higher pressure induces ordering of the membrane (less fluid)

Abnormalities of Membrane Fluidity Decreased erythrocyte membrane fluidity

• What causes ?• Due to what disease ?

Decreased lipids membrane fluidity• In what cell ?• What causes ?• What is Bassen-Kornzweig syndrome ?

1. Decreased erythrocyte membrane fluidity and altered lipid composition in human liver disease.

• Changes in erythrocyte membrane lipid composition associated with abnormal plasma lipoproteins in liver disease patient.

• Cholesterol/phospholipid and phosphatidylcholine/sphingomyeli molar ratios are increased.

• Phospholipid fatty acid composition is abnormal.– Proportion of arachidonic acid, stearic acid are

decreased while palmitic acid raised.


• Cause membrane fluidity in patient erythrocytes decrease and fluidity of lipid extracts from membranes patient erythrocytes also decrease.

• Decrease membrane fluidity is MAIN consequence of altered lipid composition rather than protein abnormalities.


• In liver disease, changes in composition of phospholipid bilayer matrix in erythrocytes membrane has little influence on its fluidity.

• Reduced fluidity predominantly result of increased in cholesterol relative to phospholipid.

2. Decreased Fluidity of Red Cell Membrane Lipids in Abetalipoproteinemia

• Acanthocytic red cells in patients with abetalipoproteinemia (Bassen-Kornzweig syndrom) are morphologically similar to red cells in spur cell anemia.

• Bassen-Kornzweig syndrome is a rare disease passed down through families in which a person is unable to fully absorb dietary fats through the intestines..

• Decrease in fluidity of membrane lipids is due to excess cholesterol content.

• Acanthocyte membranes have an increased content of sphingomyelin and a decreased content of lecithin.

2. Decreased Fluidity of Red Cell Membrane Lipids in Abetalipoproteinemia

• Increased sphingomyelin/lecithin ratio of acanthocytes is responsible for their decreased membrane fluidity.

• As in spur cells and in red cells enriched with cholesterol in vitro, this decrease in membrane fluidity occurs coincidentally with an abnormality in cell contour and an impairment in cell deformability.

Spiculated thorny RBCs (acanthocytes) in abetalipoproteinemia individual

Acanthocytes in individual with spur cell hemolytic anemia.

Summary

• Liver disease and Bassen-Kornzweig syndrome are the disease that cause decrease fluidity in cell membrane of RBCs.

• Due to increase of lipid composition.• Less permeability to water and other small

hydrophilic molecule .• Abnormalities in membrane fluidity lead to

many disadvantages.