Structure(Plasma Membrane)

A lipid bilayer(2 layers of lipids) with a variety of proteins

Lipid molecule

Proteins

Identify the lipid molecules.Identify the protein molecules.

What is a ‘lipid bilayer’?

Function

-To be Selective Permeable: =control what passes in or out of the cell

(Plasma Membrane)

-Helps maintain Homeostasis: = maintain a stable internal environment

-Act as a lining, separates the chemicals of the cytoplasm from the surroundings

What the lipids do…

(Plasma Membrane)

. 1. Form a. open channels b. gated channels

c. active transport pathways,All to move molecules in & out

of the cell!

What the proteins do…

Open channels

Ex. 1 of channel proteins.

Gated channel

Ex. 2 of channel proteins.

(Plasma Membrane)

-Receptors that change cellular activity.

Protein Function #2

Receptor protein

Signal molecule

Change cellular activity

(Plasma Membrane)

-Create a molecular mark (signature) that identifies that specific, individual cell.

Protein Function #3

Recognition protein

LOOK!

Types of particle that might cross membranes.

Tiny molecules, like…

WaterOxygen& Carbon dioxide

Types of particle that might cross membranes.

Small molecules, like…

Glucose, amino acids, fatty acids and glycerol

Water Carbon Dioxide

Oxygen

Aminoacid

Glycerol GlucoseFatty Acid

Yet more types of particles that might cross

cell membranes!Yes, even large molecules,

such as…

PolysaccharidesLipids & proteins!

Lipid soluble molecules

Fats,Fatty acids

Charged particles

ions

Na+, K+, Cl+

Even Large Particles may sometimes cross the selectively

permeable cell membrane!

Such as…small organisms and Organic debris

DiffusionMovement of particles from an area of high

concentration to an area of lower concentration.

Diffusion requires a Concentration

gradientWhen the

concentration of particles is not the same throughout a

mixture.

Concentration Gradient

There is a region of high concentration and

a region of low concentration.

Go to page 7 in the note packet and

learn about the use of square brackets.

[ ]

Do the activity The Tea Cup

& The Swimming Pool

on page 8.

EquilibriumWhen the concentration

of particles is the same throughout a mixture.

EquilibriumThere is no region of high, nor a region of low concentration of

particles.

EquilibriumAll particle continue to

move.

Diffusion

Concentrationgradient

Equilibrium

TRANSPORTThe Movement of

Materials

Across Membranes

PassiveTransport

Materials move down the concentration

gradient and across a membrane.

What determines if a particle can go through a channel?

Dialysis Tubing

OsmosisThe passive

transport of water across a membrane.

Thistle Tube Demo

watermolasses

thistle tube

Selectively permeable membrane

Active TransportParticles move

•Across a SPM.•Against the concentration gradient.

•The cells must spend energy.

Active transport allows particles to move against the

concentration gradient.(from an area of _____

concentration to an area of ___ concentration)HIGH

LOW

An exampleof Active Transport:

All animal cells have a Sodium Potassium pump that pumps sodium (Na+) to the outside of cells and potassium (K+) to the inside of cells.

This ‘pump’ allows nerve cells to carry electrical messages through the

body!

+ + + + + + + + + - - - - - - - - - - - - - - - - -

Nerve cell

The Cell Membrane of a nerve cell

EndocytosisParticles move INTO the cell by folding a portion of the membrane around a particle, resulting in a vesicle.

There are two types of Endocytosis:

Pinocytosis - drinkingDissolved materials

Phagocytosis - eatingFood particles

Pinocytosis

The solute particles are too small to see but too big to pass through the membrane.

ExocytosisParticles move OUT OF a cell by fusing vesicles with the cell membrane.

Maintaining water balance

in Protists

Facilitated Transport(Facilitated Diffusion)

-Diffusion using protein channels

Transport protein

Gated channel

The End