Vocab Word list 1. Diffusion2. Osmosis3. Selectively

permeable4. Equilibrium5. Solution6. Facilitated

Diffusion7. Hypertonic8. Hypotonic9. Isotonic10.Contractile

Vacuole

11. Passive Transport12. Active Transport13. Endocytosis14. Phagocytosis15. Pinocytosis16. Exocytosis17. Protein Pump

Know all of these words for the test

Transport Across the Cell Membrane

Silent video- cell membrane and how it works https://www.youtube.com/watch?v=QQgXfuFyKM4

Fluid Mosaic Model Video clip https://www.youtube.com/watch?v=Qqsf_UJcfBchttp://www.youtube.com/watch?v=moPJkCbKjBs&feature=relmfu

Cell MembraneStructure•Bi-layer of phospholipids with proteins imbedded

• Philic heads = water loving

• Phobic tails= water fearing

• This helps the cell interact in its aqueous environment.

FUNCTIONS1. Gatekeeper2. Protects and controls the substances going in and out

of the cell3. Selectively permeable - Only certain substances

can pass through the membrane.

Think …..How does this picture show selective permeability?

Think…..How does the gate act like a cell membrane?

•Things they want to let in:

•Things they want to let out:

•Things they DO NOT want to let in:

•The cell tries to let in good things and keep out bad

things. Often based on size…small things are allowed in and larger things are kept out or have to be pumped in.

sugar, oxygen, water

carbon dioxide, waste

viruses, bacteria

4. Recognize and respond to signals by using cell receptors (receptor molecules)•Allows cell to communicate and maintain homeostasis•Are protein molecules on the surface of the membrane with a specific shape.

Advanced video Click on image

• Cell receptors receive information from chemical messengers (i.e. hormone) by matching up with its shape signaling the target cell to respond and produce a desired product

Protein(cell)

Receptor

CellMembran

e

Insulin

TYPES OF TRANSPORT http://www.youtube.com/watch?v=kfy92hdaAH0

No energy required Energy required

1. Passive Transport

• Requires NO energy• Diffusion & Osmosis and Facilitated

Diffusion – carrier proteins “help” molecules across the membrane

http://www.brainpop.com/science/cellularlifeandgenetics/passivetransport/zoom.weml

Diffusion• molecules move from an area of

high concentration to an area of low concentration

• Molecules tend to “spread out”• Requires NO energy• Substances that may diffuse:

• Oxygen, carbon dioxide, glucose, amino acids, water

Click on image

Equilibrium• When molecules are evenly spread

throughout a space

Osmosis• Diffusion of

water molecules.

Cells in different osmotic solutions

• Cells behave differently when placed in different solutions!

• This is due to OSMOSIS!– Most cells are ~ 98% water!

• Three types of osmotic pressure:– Isotonic– Hypotonic– Hypertonic

Watch How osmosis works:https://www.youtube.com/watch?v=w3_8FSrqc-I

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.htm l

Basic Rule for Determining types of Osmostic conditions…..

If the area outside the cell has more salt – then water will be “pulled” out of the cell

•Watch the animation

U - Tubes

Isotonic - "ISO" means the same

Let’s see….Isotonic ConditionLet’s see….Isotonic Condition

• Cell is placed in 98% water– Solution outside of cell has SAME water,

same amount of other materials (i.e., salt)• Therefore, solution is equal strength (iso)

Water moves equally; Equilibrium exists

98%

98%

CELLSTAYSTHE SAME!

Hypotonic (Hypo = less)• Water moves in the cell • Cell may burst, or organelles called

“contractile vacuoles” remove excess water

Let’s see…Hypotonic ConditionLet’s see…Hypotonic Condition

• Cell is placed in 100% water– Solution outside of cell has MORE water,

less of other materials (i.e., salt)• Therefore, solution is below strength (hypo)

98%

Water ENTERS cell100%

CELLSWELLS!

Why is it dangerous to drink sea water?

Why does pouring salt on a slug kill it?

• Water moves out of cell • Cell will shrink (Plasmolysis) or die,

plants wilt

HYPERTONIC – “Hyper = above”

Let’s see… Hypertonic ConditionLet’s see… Hypertonic Condition

• Cell is placed in 95% water– Solution outside of cell has LESS water, more

of other materials (i.e., salt)• Therefore, solution is above strength (hyper)

Water LEAVES cell

98%

95%

CELL SHRINKS!

Gummy Bear Osmosis Lab

WATER RELATIONS AND CELL SHAPE IN CELLS

HYPERTONICHYPOTONIC HYPOTONIC HYPERTONIC

Animal cell: RBC Plant Cell

Facilitated Diffusion• Facilitate- to guide or

help.• Protein channels help

guide some molecules through the cell membrane.

• Watch animation

Let’s see!

2. Active Transport • Watch video: https://www.youtube.com/watch?v=2-icEADP0J4

• Movement of molecules from areas of low concentration to areas of high concentration.

• Requires ATP (energy).

• Against the concentration gradient

http://www.brainpop.com/science/cellularlifeandgenetics/activetransport/

Molecule tobe carried

LowConcentration

CellMembrane

HighConcentration

Moleculebeing carried

LowConcentration

CellMembrane

HighConcentration

EnergyEnergy

Figure7-20 Active Transport

Go to Section:

Active Transport

Examples of Active Transport :1. Endocytosis- bring into the cell.

2. Exocytosis- move out of the cell.

endo=within exo=outside cyt=cell osis = process of

Endocytosis and Exocytosis

Phagocytosis• Cytoplasm extends out and engulfs

material to be brought into the cell.

• White blood cells and amoeba.

Watch animation: http://www2.sluh.org/bioweb/bi100/tutorials/thecell/phago_4.html

Watch Summary video• Active & passive transport

-http://www.youtube.com/watch?v=kfy92hdaAH0