Chapter 5 Chapter 5

Membrane Structure and Function Membrane Structure and Function part Ipart I

Page ref. 84-86Page ref. 84-86

Memorize these words!!!Memorize these words!!!

inter – within ie. Hilo to Honoluluinter – within ie. Hilo to Honolulu intra – between, among ie. Hilo to Konaintra – between, among ie. Hilo to Kona extra – outside of (extracellular would be extra – outside of (extracellular would be

outside the cell)outside the cell) glyco – containing sugar/carbohydrates glyco – containing sugar/carbohydrates

(sugar-coated)(sugar-coated)

The fluid-mosaic model of The fluid-mosaic model of the plasma membranethe plasma membrane

The cell membrane is The cell membrane is a fluid, phospholipid a fluid, phospholipid bilayer in which bilayer in which protein molecules protein molecules are either fully or are either fully or partially embedded. partially embedded. (see fig. 5.1 and 5.2) (see fig. 5.1 and 5.2)

Plasma membrane Plasma membrane functionsfunctions

to separate the internal from external to separate the internal from external environment of the cellenvironment of the cell

Regulates materials entering and leaving Regulates materials entering and leaving the cell.the cell.

Helps the cell, in turn the organism, Helps the cell, in turn the organism, maintain homeostasismaintain homeostasis

Plasma membrane Plasma membrane structurestructure

Made up of a Made up of a phospholipid bilayerphospholipid bilayer PhospholipidPhospholipid: a : a

molecule with a molecule with a hydrophilic (water-hydrophilic (water-loving) head and a loving) head and a hydrophobic (water-hydrophobic (water-fearing) tailfearing) tail

Plasma Membrane Plasma Membrane ComponentsComponents

Cholesterol: a lipid found in bilayer, for strength Cholesterol: a lipid found in bilayer, for strength of membraneof membrane

Proteins: peripheral (inside surface of Proteins: peripheral (inside surface of membrane) or integral (embedded in membrane) or integral (embedded in membrane)membrane) Some integral proteins protrude from one surface of Some integral proteins protrude from one surface of

bilayer, some protrude from both (transmembrane)bilayer, some protrude from both (transmembrane)

Phospholipids and proteins can have attached Phospholipids and proteins can have attached carbohydrate (sugar) chains. These are called carbohydrate (sugar) chains. These are called glycolipids, and glycoproteins, respectivelyglycolipids, and glycoproteins, respectively

Carbohydrate ChainsCarbohydrate Chains

Carbohydrate chains of proteins in Carbohydrate chains of proteins in animal cell give cell a “sugar coat” called animal cell give cell a “sugar coat” called the glycocalyx.the glycocalyx.

Functions of the glycocalyx include Functions of the glycocalyx include protection of the cell, enables cells to protection of the cell, enables cells to adhere to one another, reception of adhere to one another, reception of signal molecules, and for cell-to-cell signal molecules, and for cell-to-cell recognitionrecognition

Fluidity of Plasma Fluidity of Plasma MembraneMembrane

Membrane fluidity critical to it’s Membrane fluidity critical to it’s functioningfunctioning

At body temperature, it has the At body temperature, it has the consistency of olive oilconsistency of olive oil

This allows the cell to do all it needs to This allows the cell to do all it needs to do – it makes the cell pliabledo – it makes the cell pliable

HomeworkHomework

Due ThursdayDue Thursday All vocab ANDAll vocab AND Reviewing chapter - #1-3Reviewing chapter - #1-3 Testing yourself 2,3,11,12,13,14Testing yourself 2,3,11,12,13,14