CELL MEMBRANE

Types of Movement Through Cells #1) Diffusion #2) Osmosis #3) Facilitated Diffusion #4) Active Transport

Learning Objective We are going to learn about: What diffusion is Everyday examples of diffusion What is meant by a concentration gradient and how this affects rate of diffusion Biological examples of diffusion

BUT FIRST!

Solute + Solvent = Solution

Solutions are made of solute and a solvent SOLUTE - substance that is dissolved or put into the solvent. Salt and sucrose are solutes. SOLVENT - the liquid into which the solute is poured and dissolved. We will use water as our solvent today. SOLUTIONS

WHICH ONE IS MORE CONCENTRATED? Demo.

What will eventually happen to these dyes? They will all blend together. The dyes will move through the water until an even distribution is achieved. The process of moving from areas of high amounts to areas of low amounts is called diffusion.

DIFFUSION

Diffusion in Action- In the Air Close your eyes. Your teacher will spray some fragrance at the front of the room. When you can smell it open your eyes and look around. What did you notice?

Maybe you can smell your dinner cooking when you get home... This is due to diffusion.

Diffusion & Life How can a shark find injured prey so quickly?

DIFFUSION Food, water, and other substances are made of different kinds of particles, such as molecules and ions.  Particles are always moving, like dancers on a crowded dance floor.

You can tell how particles will tend to move if you know how crowded they are. Concentration refers to how crowded particles are. A juice concentrate is a very strong form of juice. It has many more juice particles than regular juice does.

In a concentrate, the juice particles are very crowded.  When you mix the concentrate with water, the juice particles spread out in the water. They tend to move away from places where they are concentrated  Thus, the particles become less concentrated.

Particles will continue to move from areas of high concentration to areas of low concentration until they reach equilibrium. This process is called diffusion.

HIGH to LOW

DIFFUSION

Diffusion

Reflect back on the demonstration with food coloring in water, then answer the following:  Explain why the ink spreads out in the water. Use the words concentration and diffusion in your answer.

SO WHY AM I LEARNING THIS???? WHY is THIS important?? BECAUSE, Diffusion is an important process that allows a cell to get substances it needs.

Just as food coloring diffuses in water, some substances can diffuse into and out of a cell through its cell membrane.

Diffusion Through a Cell Membrane Cells also need food and water to live Substances move into and out of the cell through its cell membrane A cell membrane is like the cell’s skin.

Nutrients and oxygen pass from the mother to baby by DIFFUSION

Diffusion and Digestion Digestion breaks down large food molecules into smaller molecules such as glucose, amino acids and fatty acids that can be easily absorbed. Small food molecules are usually absorbed in the small intestine, diffusing across the intestine wall and into the bloodstream.

Oxygen moves into your body through DIFFUSION

Reviewing Vocabulary 1.Some substances move into and out of cells by D_____________. 2.The word C________________ refers to how crowded particles are. 3.Some particles diffuse into and out of cells through the C____ M_________. 4.Particles tend to move from a H___ concentration to a L____ concentration. 5.Give one example of diffusion in your home.

OSMOSIS Most of your body is made of water. This water can move into and out of your cells Water can enter and leave your cells by diffusion.  When water DIFFUSES through a CELL MEMBRANE, the process is called OSMOSIS.

 In the picture, water is diffusing through a cell membrane.  Why is the water moving INTO the cell in the picture? Water particles Outside of Cell Inside of Cell Cell Membrane

Because water has a lower concentration inside the cell than outside the cell. Water moves into the cell by OSMOSIS.

What happens to the raisin after sitting in the water for a while?  It becomes larger  Why does this happen?

Water molecules have a lower concentration inside the raisin. Outside the raisin, water molecules are crowded. Water molecules diffuse into the raisin by osmosis.

Cells do not use energy to move particles by osmosis or diffusion Particles move freely into and out of cells. This kind of movement is called PASSIVE TRANSPORT  Complete the Vocabulary Review. PASSIVE TRANSPORT Diffusion, Osmosis and facillitated diffusion are all types of passive transport

Vocabulary Review 1.One example of osmosis is water diffusing into a raisin. 2.Cells do not work to move molecules by passive transport. 3.Two forms of passive transport are osmosis and diffusion. 4.In diffusion and osmosis, particles move by themselves. 5.Water molecules tend to move to places where they have a low concentration. 6.Give one way that osmosis is similar to diffusion. Both move from high to low concentration.

Active vs. Passive Transport Passive Transport – does not require energy. Particles move from high to low concentration. Active Transport – does require energy because molecules are moving from low to high concentration

Endocytosis Some things the cells needs are too large to pass through the cell membrane. The cell membrane can surround a large particle located outside the cell.  The membrane forms a sac around the particle.  Then the sac opens inside the cell.

Large particle leave the cell in sacs too. Inside a cell, a sac forms around large waste particles. The sac moves to the membrane and then opens outside the cell. Waste particle move OUTSIDE the cell. This process of moving large particles OUT of the membrane is called EXOCYTOSIS.

Cells Maintain Balance The cell controls its food and water content by moving ions, molecules, and larger particles into or out of itself. This is how the cell maintains homeostasis. Homeostasis Simulation 17/hot_guy.html Complete the Vocabulary Review

Vocabulary Review 1.Cells use energy to move molecules by active transport. 2.Diffusion and osmosis are two kinds of passive transport. 3.Some molecules are too large to pass through the cell membrane. 4.Cells take in large molecules by endocytosis. 5.Cells must maintain a balance, called homeostasis.