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Material Flow in the Cell. Semipermeable Membrane. The Cell Membrane is a Semipermeable membrane – it keeps some things out and lets some things in. Protects contents of cell from outside world. Proteins are the bouncers. What Materials can Pass?. What can come into the cell?

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Semipermeable membrane
Semipermeable Membrane

  • The Cell Membrane is a Semipermeable membrane – it keeps some things out and lets some things in.

  • Protects contents

    of cell from outside

    world.

  • Proteins are the

    bouncers


What materials can pass
What Materials can Pass?

What can come into the cell?

Oxygen & food & proteins

What goes out of the cell?

Waste materials

What is not allowed in?

Poison and waste


Passive transport
PASSIVE TRANSPORT

  • PASSIVE TRANSPORT – ways to move material into and out of the cell without using any energy.

    2 Ways:

    • DIFFUSION

    • OSMOSIS – a type of diffusion


Diffusion
DIFFUSION

  • The main method by which small molecules move across the cell membrane.

  • The molecules move from an area of HIGHER CONCENTRATION to an area of LOWER CONCENTRATION.

  • Oxygen molecules commonly move into and out of the cell by Diffusion.

  • USES NO ENERGY (passive transport)


Diffusion demo
DIFFUSION DEMO

BEFORE

AFTER


Diffusion1
DIFFUSION

AFTER

BEFORE


What causes diffusion
What Causes Diffusion?

  • Molecules are always moving and they bump into each other.

  • When they bump into each other they push each other away and spread out.

  • Eventually they spread throughout the whole area.

  • NO ENERGY NEEDED by cell because the molecules have energy in their vibrations.


Osmosis
OSMOSIS

  • A special kind of diffusion

  • The diffusion of water molecules through the cell membrane.

  • Water still moves from HIGHER CONCENTRATION to LOWER CONCENTRATION.

  • USES NO ENERGY (passive transport)





POTATO FISH!!!!

  • Take out a sheet of paper!

  • Write down observations of both of your potato slices.

  • Put your name on both cups

  • Label one cup SALT and one cup FRESH

  • Put the same amount of water in each cup

  • Put salt in the cup that is labeled salt (amount does not matter, just make sure it dissolves!)

  • Put one potato slice in the FRESH cup and one in the SALT cup

  • We are going to leave the potatoes in their cups over night.

  • Write down your predictions. WHAT DO YOU THINK WILL HAPPEN TO EACH OF THE POTATOES?


Active transport
ACTIVE TRANSPORT

  • Active Transport – USES ENERGY to move materials into and out of the cell.

  • Often from LOW concentration to HIGH concentration

  • For small or large particles

  • This requires the cell to USE ENERGY.

    2 ways:

    • ENDOCYTOSIS

    • EXOCYTOSIS


Endocytosis
ENDOCYTOSIS

  • USES ENERGY (active transport)

  • Large particles are taken INTO THE CELL

  • Particles include PROTEIN and FOOD


Endocytosis draw these steps
ENDOCYTOSIS – draw these steps

energy

energy

A WANTED

MOLECULE

STEP 1:

The cell membrane

touches the wanted

molecule.

1


Endocytosis1
ENDOCYTOSIS

energy

energy

STEP 2:

The cell wraps

itself around

the molecule.

2


Endocytosis2
ENDOCYTOSIS

energy

STEP 3:

The molecule

forms a Vacuole.

3


Endocytosis3
ENDOCYTOSIS

energy

STEP 4:

The cell

membrane

closes.

4


Transport proteins
TRANSPORT PROTEINS

  • These are special Proteins called Transport Proteins that are attached to the cell membrane.

  • They “PICK UP” the wanted molecules inside or outside of the cell and carry them in or out using energy.

  • Common Materials transported this way:

    • Calcium, Potassium, and Sodium.


Transport proteins1

CYTOPLASM OUTSIDE THE

CELL

HIGH LOW

CONCENTRATION CONCENTRATION

TRANSPORT

PROTEIN

TRANSPORT PROTEINS

BEFORE


Transport proteins2
TRANSPORT PROTEINS

CYTOPLASM OUTSIDE THE

CELL

HIGH LOW

CONCENTRATION CONCENTRATION

USES ENERGY

AFTER


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