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Aim: How does the plasma Aim: How does the plasma membrane help to maintain a membrane help to maintain a cells’ homeostasis?cells’ homeostasis?

Do now: Do now:

why do buildings use gates? why do buildings use gates?

Gates…Gates…

Keep unwanted peopleKeep unwanted people

Let in wanted peopleLet in wanted people

They help us be selective They help us be selective on who can enter. on who can enter.

Gates…Gates…

Keep unwanted peopleKeep unwanted people

Let in wanted peopleLet in wanted people

They help us be selective They help us be selective on who can enter. on who can enter.

The Plasma Membrane works like a gate to the cell, it keeps unneeded substances out and allows needed

substances in.

What is the role of the What is the role of the plasma membrane?plasma membrane?

Activity- Close ReadingActivity- Close Reading

The Plasma The Plasma Membrane Membrane

And HomeostasisAnd Homeostasis

Homeostasis – Homeostasis – Maintaining a BalanceMaintaining a Balance

Cells must keep the Cells must keep the proper concentration proper concentration of nutrients and water of nutrients and water and eliminate wastes.and eliminate wastes.

Is selectively permeable(picks Is selectively permeable(picks and chooses) – it will allow some and chooses) – it will allow some things to pass through, while things to pass through, while blocking other things.blocking other things.

Plasma Membrane Plasma Membrane (Cell membrane)(Cell membrane)

Selectively PermeableSelectively Permeable

Structure of the Plasma Structure of the Plasma MembraneMembrane

The plasma membrane is composed The plasma membrane is composed of a phospholipid bilayer of a phospholipid bilayer

((2 layers2 layers of phospholipids) of phospholipids)

In your notebook draw the In your notebook draw the following picture of the following picture of the plasma membrane. plasma membrane.

Transport ProteinsTransport Proteins the channel for the channel for nutrients, water & waste to get into nutrients, water & waste to get into and out of the cell. and out of the cell.

No everything can get into the cell No everything can get into the cell The Plasma membrane lets in The Plasma membrane lets in small molecules (water, sugar)small molecules (water, sugar)

The Plasma membrane keeps out The Plasma membrane keeps out larger molecules (starch)larger molecules (starch)

The Plasma Membrane The Plasma Membrane Discriminates…Discriminates…

Plasma Plasma Membrane Membrane VisualVisual

http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio04.swf::Cotransport

DiffusionDiffusion

The movement of The movement of substances across the substances across the plasma membrane plasma membrane without the use of without the use of energy.energy.

{{Tomorrow we will Tomorrow we will learn more about learn more about

DiffusionDiffusion

Reading- Answer Reading- Answer QuestionsQuestions

HomeworkHomework

AssessmentAssessment