Modal membrane of the plasma membrane, part one comprising of introduction, functions, composistion lipids of the plasma membrane, biosynthesis of membrane lipids, assemly of newly synthesized lipids,modal membranes. Part 2 of the slides will updated soon.

1. Modal Membranes: Structure
and function(Part one)
Ekeh Chukwuemeka Obinna

2. Introduction
● Types of biological cells eg Prokaryotic cells and Eukaryotic
cells
● Prokaryotic cells: They are unicellular cells eg Eubacteria
and Archaea.

3. ● Eukaryotic cells: They are multicellular eg plant and animal
cell.

4. Functions of plasma membrane
● They maintain cellular integrity by controlling the
transport of substances into and outside the cell
● They mediate cellular interaction with extracellular cells
or matrix. The receptors are responsible for signal
transduction.
● They are involved in specialized functions in some cells

5. ● Plasma membranes are amphipathic in nature. They have
hydrophobic and hydrophilic ends.
● Constituents of the plasma membrane are mostly lipids,
protein, carbohydrates.
● Lipids of the plasma membrane are phospholipids,
glycolipids, sterol, lipopolysaccharide, sphingolipids.
● Membrane protein are responsible for cell adhesion, energy
transduction, signaling, transport and cell recognition.

6. Lipids of plasma membrane
● Phospholipids:They are the abundant lipids in the membrane eg
phosphatidylcholine, phosphatidic acid, phosphatidylethanolamine,
phosphatidylglycerol, phosphatidylinositol.

7. ● Sphingolipids eg phosphosphingolipids and
glycosphingolipids. They found mainly of membrane
of sphingomyelin cells.
● Glycolipids eg monogalactosyl diglyceride and
digalactosyl diglycerides
● Sterols eg cholesterol, ergosterol, sitosterol,
lanosterol.

9. ● Biosynthesis of membrane lipids

10. Assembly of new synthesized lipids into
membranes
● They are incorporated into existing membrane
● The active site of enzymes involved in lipid synthesis mediates the
asymmetry distribution of lipids
● Protein ATP pump unidirectionally pump lipids maintaining
asymmetry distribution
● Membrane curvature, disruption of plasma membrane by
fusion/fission .

11. ● Detergents disrupt membranes by disaggregating and solubilizing
nonpolar lipids, bilayers, proteins. The enable digestion of fats.
● Non ionic detergents have polar head group that carry no charge eg
beta-D-glucopyranoside, digitonin. They are widely used in the lab.
● Ionic detergents have net charge on polar head group. They destroy
proteins. Eg sodium dodecyl sulfate, sodium cholate.
● Properties of detergents: They are amphipathic, have difficulty filling
the interior of lipid bilayer thereby forming spherical micelle.

12. Membrane Models
● Green and perdue model: Lipid-protein complex with proteins buried
in lipid bilayer.
● Singer Nicolson Model(fluid mosaic model: Membranes are fluid and
diffuse laterally in the lipid bilayer. They propose two classes of
membrane protein( integral and peripheral proteins)