Chapter 7.3 Cell Transport - PowerPoint Presentation

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Chapter 7.3

Cell Transport

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Warm-Up

What do you know so far about the cell membrane?

What do you want to know about the cell membrane?

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Cell Membrane Structure & Function

Phospholipid

Bi-layer

(hydrophilic heads, hydrophobic tails)

Fluid-Mosaic ModelProteins & cholesterol embedded within the phospholipid bi-layerSelectively Permeable – controls was enters and exits the cell

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Fluid-Mosaic Model

Channel Proteins:

Allow molecules,

such

as water, to pass through the cell membrane

Recognition/ID Protein:Has carbohydrate chains attached that are used as ID markersAllow cells to communicate with eachother and identify foreign invaders (other blood type, virus)

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Protein Pump:

Use ATP (energy) to pump substance across the membrane

Fluid-Mosaic Model

Cholesterol:

Lipid that controls the

fluidity of the cell membrane

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Cell membrane transport

There are 2 types of cell membrane transport:

Passive Transport

Things flow from

High to lowActive TransportThings flow from Low to high

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Another perspective on passive and active transport

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Passive Transport

Diffusion

The movement of particles from areas of high concentration to low concentration

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

http://www.biosci.ohiou.edu/introbioslab/Bios170/diffusion/Diffusion.html

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Equilibrium

When is equilibrium reached when discussing cell membrane transport?

When the concentrations of particles are the same on both sides

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Facilitated Diffusion

Particles flow from high concentration to low concentration but this time they need the help of proteins to get through the cell membrane.

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Facilitated diffusion

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Passive transport

Osmosis

The diffusion of water across a selectively permeable membrane

Important in maintaining cell homeostasis

Water flows to side of membrane where the water concentration is lower until equilibrium is reached

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Osmosis

Osmosis is controlled by the amount of solutes on either side of a membrane

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Osmosis – Types of Solutions

When dealing with osmosis, water can either move into the cell or out of it.

The solute can not move to equal out the solution so the water has to.

We describe the solutions that cells are in as either hypotonic, isotonic, or hypertonic.

What are the concentrations?

90%40%

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Isotonic Solution

Isotonic solution – Concentration of solute is the same in the cell and the area around the cell.

Give me an example of an isotonic solution that some of you use everyday

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Isotonic solution

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Hypotonic Solution

Hypotonic Solution – Concentration of solute is lower in the solution than in the cell.

Where is water going to move in order to reach equilibrium (Equal concentrations)?

Inside the cell

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Hypotonic solutions

Since water moves into the cell the cell can explode

http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

So, Hypotonic solution, low concentration of solute, cell can explode

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Plant and animal cells in a hypotonic solution

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Hypertonic Solution

Hypertonic solution – concentration of solute is higher in the solution than in the cell.

Where is water going to move in order to reach equilibrium (Equal concentrations)?

Outside the cell

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Hypertonic solutions

Since water moves out of the cell the cell will shrink

http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

So, Hypertonic solution, high concentration of solute, cell will shrink

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Plant and animals cells in a Hypertonic Solution

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Osmosis

http://www2.nl.edu/jste/osmosis.htm

http://www.coolschool.ca/lor/BI12/unit4/U04L06/rbc.html

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Active Transport

Molecules move from low concentration to high concentration

Requires energy….why?

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Active Transport

Molecular Transport –

Protein Pumps

Small molecules and ions carried across the cell membrane by proteins in the membrane that act like pumps

Bulk TransportEndocytosis – in!Exocytosis – out!

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Other membrane transport activities that require energy

Endocytosis

Engulfing of large particles or liquids from outside the cell

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2 types of Endocytosis

Phagocytosis

Engulfing of large particles

from outside the cell

PinocytosisEngulfing of liquids from outside the cell

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Other membrane transport activities that require energy

Exocytosis

Release of large particles or liquids from inside the cell

Inside the cell

Outside the cell