Cell Membrane and Transport

PHYSIOLOGY

CELL MEMBRANE AND TRANSPORT (1st Lec)

DR. MILAGROS B. RABE

OBJECTIVES

1.

2.

3.

4.

5.

6.

I.

• In 1972, J. Singer and G. Nicolson proposed that the

membrane is a mosaic of proteins dispersed within the bilayer

Give the functions of the cell membrane

Describe the Fluid-Mosaic model of the plasma

membrane.

Give the composition of the plasma membrane

-Identify the different lipids and their roles

-Enumerate the types of proteins and their functions

-Give the roles of carbohydrates in the membrane.

Describe the membrane transport systems.

Describe the transmembrane transport.

-Explain Fick’s Law of Diffusion.

-Differentiate active and passive transport.

-Give examples of each type of transport systems

Describe transport across the cell membrane.

-Classify the types of endocytosis.

-Describe exocytosis.

JUNE

 18

 2014

Cell

FLUID MOSAIC MODEL

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Fluid Mosaic Model – cellular membranes are fluid

structures

o

o

Lipids and Proteins may move freely in the

6/18/2014

membrane but they go from one

phospholipid to another (“flip-flop”) at a slow

rate.

Not all membrane components can be

diffused through the membrane.

B. MEMBRANE STRUCTURE

The most abundant constituents of the cellular

membrane are the proteins and phospholipids.

II.

CELL MEMBRANE

A. FUNCTIONS OF CELL MEMBRANE

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regulate TRANSPORT of molecules into and out of

cell (selective permeability)

cell RECOGNITION (surface antigens)

cell COMMUNICATION (neurotransmitters,

hormones, signal transduction)

TISSUE ORGANIZATION – temporary and

permanent cell junctions; cell adhesion molecules

ENZYMATIC ACTIVITY – when external  internal

Determination of cell SHAPE – link to cytoskeleton

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1. Phospholipids

Consists of a polar head group and two nonpolar,

hydrophobic fatty acyl chains

Tends to orient with their hydrophobic fatty acyl

chains away from contact with...