Cell transport
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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. Hypertonic11. Hypotonic 12. Isotonic.

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CELL TRANSPORT

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Cell transport

CELL TRANSPORT


Define these terms

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. Hypertonic11. Hypotonic

12. Isotonic


How do molecules get into the cell

How do molecules get into the cell?

  • By crossing the Cell Membrane!


What is a key property of 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

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

First type Passive Transport-Diffusion

  • What is it?

    • Random movement of moleculesdown a concentrationgradientfrom an area of highconcentrationto an area of lowconcentration.

  • NOenergy is expended.

  • ALWAYS high concentration to low concentration!


Diffusion

Diffusion


Watch this animation

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

2nd type Passive Transport-Osmosis

  • The diffusion of water across selectively permeable membranes.

  • Watermoves from a high water concentrationto low water concentration.

  • NO energy expended by cell


Cell transport

3nd type passive transportFacilitatedDiffusion

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

Always high concentration to Low concentration

!


Question what s in a solution

Question:What’s in a Solution?

Answer:

  • solute+solventsolution

  • NaCl+H20saltwater


Hypertonic

solution

3% NaCl

5% NaCl

97% H2O

95% H2O

Red Blood Cell

Hypertonic

  • A solution with greater solute concentration (less water) compared to inside the cell.


Hypotonic

3% Na

solution

97% H2O

1% Na

99% H2O

Red Blood Cell

Hypotonic

  • A solution with lower solute concentration (more water) compared to inside the cell.


Isotonic

solution

3% Na

97% H2O

3% Na

97% H2O

Red Blood Cell

Isotonic

  • A solution with an equal solute concentrationcompared to inside the cell.

  • This solution is said to be in Dynamic equilibrium.


Movement of h 2 o osmosis

Movement of H2O = OSMOSIS!

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

    ALWAYS REMEMBER- water moves from

  • HYPOTONICHYPERTONIC


Animal cells

Red

Blood

Cell

Animal Cells

  • Animal cells placed into a hypotonic solution will EXPLODE.

Hypotonic


Animal cells1

Red

Blood

Cell

Animal Cells

  • Animal cells placed into a hypertonic solutionwill SHRIVEL.

Hypertonic


Plant cells

Water

Water

Central

Vacuole

Cell

Wall

Water

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.


Plant cells1

Water

Water

plasma membrane

Cell

Wall

Water

Plant Cells

  • In a hypertonic environment(loss of water), the plasma membrane pulls away from the cell wall(vacuole empty).


Active transport

Active Transport

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


Examples of active transport

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

Protein pumps

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

  • Sodium potassium pump animation.


Cell transport

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

  • Endocytosis and Exocytosis (BOTH are active transport!)


En docytosis

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!!


En docytosis cont

Endocytosis, cont.

Different names for type macromolecules endocytosed:

  • Pinocytosis: endocytosis of liquids

  • Phagocytosis: endocytosis of particles

  • http://www.stolaf.edu/people/giannini/flashanimat/cellstructures/phagocitosis.swf


Endocytosis cont

Endocytosis, cont.

  • Amoeba feeding


Ex ocytosis

Exocytosis:

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

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


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:

baggies

Starch suspension in H2O

Iodine solution

Beakers

MODELLING A CELL MEMBRANE


Wrap up of transport across a semipermeable membrane

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

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?


Cell transport

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

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 up1

Wrap-up!

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


Do now

DO Now!

  • Sheet 3.5

    • Complete and we will discuss it


Concentration problems in each problem below the membrane is permeable to water only

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 ________.


Cell transport

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!)


Cell transport

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 transport

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

Cell

0.45 M

solute

0.35 M solute

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


Cell transport

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?


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