CELL TRANSPORT

Define these terms:

1. Solute * 2. Solvent *

3. Semipermeable Membrane*

4. Passive Transport* 5.Active Transport*

6. Diffusion* 7. Osmosis*

8. Concentration Gradient

9. Facilitated Diffusion

10. Hypertonic 11. Hypotonic

12. Isotonic

Research the Following

How do molecules get into the cell?

•By crossing the Cell Membrane!

What is a key property of the Cell Membrane?

• Selective Permeability!!• This property of biological

membranes allows some substances to cross more easily than others.

How much energy will it cost the cell to MOVE molecules in

or out? • It depends on HOW it enters the cell!

• Which do you think does NOT “cost” the cell energy- Passive Transport or ActiveTransport?

PASSIVE TRANSPORT

First type Passive Transport- Diffusion

• What is it?

–Random movement of molecules down a concentration gradient from an area of high concentration to an area of low concentration.

• NO energy is expended.

Diffusion

Watch this animation!

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

• http://www.indiana.edu/~phys215/lecture/lecnotes/diff.html

2nd type Passive Transport- Osmosis

• The diffusion of water across selectively permeable membranes.

• Water moves from a high water concentration to low water concentration.

• NO energy expended by cell

3nd type passive transport Facilitated Diffusion

Type which uses transport proteins to move molecules across the membrane WITHOUT any energy expended by cell!

Question:What’s in a Solution?

Answer:

• solute + solvent solution

• NaCl + H20 saltwater

Hypertonic• A solution with greater solute concentration

(less water) compared to another solution.

3% NaCl97% H2O

Red Blood Cell

5% NaCl

95% H2O

solution

Hypotonic

• A solution with lower solute concentration (more water) compared to another solution.

3% Na97% H2O

Red Blood Cell

1% Na99% H2O

solution

Isotonic

• A solution with an equal solute concentration compared to another solution.

• This solution is said to be in equilibrium.

3% Na97% H2O

Red Blood Cell

3% Na97% H2O

solution

Movement of H2O = OSMOSIS!

• Water will “ALWAYS” diffuse down a concentration gradient from a HYPOTONIC solution (more water, less solute) to a HYPERTONIC solution (less water, more solute).

ALWAYS REMEMBER- water moves from• HYPOTONIC HYPERTONIC

Animal Cells

• Animal cells placed into a hypotonic solution will EXPLODE.

Hypotonic

RedBloodCell

Animal Cells

• Animal cells placed into a hypertonic solution will SHRIVEL.

Hypertonic

RedBloodCell

Plant Cells• In a hypotonic environment, the vacuole is full

of water (cell gains water), and the cell membrane is pushed against the cell wall. The cell wall helps the plant cell retain its shape under the tension.

WaterWater

CellWall Water

CentralVacuole

Plant Cells• In a hypertonic environment (loss of water),

the plasma membrane pulls away from the cell wall (vacuole empty).

Water Water

CellWall Water

plasma membrane

Active Transport

• The movement of molecules (small or large) across the plasma membrane using energy (ATP).

Examples of Active Transport:

Active transport using a carrier molecule in the membrane

- many times, this involves moving molecules from a low to high concentration (OPPOSITE the direction during diffusion!).

- Requires ATP (ENERGY!!) to move it across!

Protein pumps

• Some membrane proteins use energy to pump substances in and out of the cell.

• Sodium potassium pump animation.

• How are large molecules transported into and out of the cell?

• Endocytosis and Exocytosis (BOTH are active transport!)

Endocytosis• ENTRY into cell

• Portion of the membrane surrounds or engulfs a macromolecule (large molecule) outside cell. The membrane pinches off to form a vesicle in the cytoplasm

• Requires Energy!!

Endocytosis, cont.Different names for type macromolecules

endocytosed:

–Pinocytosis: endocytosis of liquids–Phagocytosis: endocytosis of

particles – http://www.stolaf.edu/people/giannini/flashanimat/cellstructures/phagocitos

is.swf

Endocytosis, cont.

• Amoeba feeding

Exocytosis:

• EXPORT of materials OUT of the cell (wastes, cell products)

- Also a type of Active Transport (energy required!!)

Quick Quiz• 1. Which type of transport REQUIRES

energy? • 2. Which type of transport does NOT

require energy?• 3. In a Hypertonic solution, the amount of

solute is _________ in the solution than the solute concentration inside the cell.

• 4. In an Isotonic solution, the amount of solute is __________ the solute concentration inside the cell.

Quick Quiz, cont.

• 5. Movement of macromolecules OUT of the cell is called __________. Does this require energy?

• 6. Endocytosis that involves movement of liquids into the cell is called ______________. Does this require energy?

MODELLING A CELL MEMBRANE

Plastic baggies are a lot like cell membranes; they are semipermeable.

• Do baggies allow any of the following - water, starch, or iodine - to move through them?

• Materials:1.baggies2.Starch suspension

in H2O3.Iodine solution4.Beakers

DO Now!

• Sheet 3.5–Complete and we will discuss it

Concentration ProblemsIn each problem below, the membrane is

permeable to water only!

1. Which way will water move – into or out of the body cell? (draw an arrow!)

2. The solution is ________.

3. Which way will water move – into or out of the sphere? (draw an arrow!)

4. Is the solution in the beaker hypotonic, isotonic, or hypertonic compared to the cell? (Circle one!)

5. Which way will water move – into or out of the sphere? (draw an

arrow!)

6. What will happen to the shape / size of the sphere? What is the solution outside the cell?

Cell

0.45 M

solute

7. Which way will water move – into or out of the body cell? (draw

an arrow!)

8. What is the cell’s solute concentration after dynamic equilibrium is reached?

0.35 M solute

9. Which way will water move – into or out of the body cell? (draw an

arrow!)

cell

10. What is the cell’s water concentration after dynamic equilibrium is reached?

Wrap up of Transport across a Semipermeable membrane!

• BEFORE you get your beaker, write down what you EXPECTED to happen? (Who moved across the plastic membrane?)

How did your experiment work? • Did the liquid in the beaker or the

baggie change color? What does it indicate?

• Decide WHICH molecules were transported- water, iodine, or starch?

• Did your experiment test all 3 components?

Cont….• Things to think about:

–Size of atoms/ molecules–Set-up of experiment- could you

detect movement of ALL molecules?–Validity/ reliability

• How is the baggy LIKE a cell membrane?

• How is it NOT LIKE a cell membrane?

Wrap-up!• Standard 10.1: FUNDAMENTAL life

processes depend on the physical and chemical activities of the cell.–D30. Explain the role of the cell

membrane in supporting cell functions.• What ARE the roles of the cell

membrane?

Wrap-up!

How is the cell membrane structured to ensure efficiency and survival?