7.3 Cell Transport✓ How do membranes help cells react with other

cells? ✓ What are the different methods cells use to

transport material? ✓ Why is active transport so important?

∗ All organisms must achieve homeostasis, relatively constant internal physical and chemical conditions.

Passive Transport

∗ Passive transport - movement of materials across the cell membrane without using energy.

Passive Transport

∗ Diffusion - The process by which particles move from an area of high concentration to an area of lower concentration.

Diffusion

∗ Facilitated Diffusion - Molecules that cannot directly diffuse across the membrane pass through special protein channels. ∗ Aquaporins allow water to pass right

through the lipid bilayer. Without aquaporins, water would diffuse in and out of cells very slowly.

Osmosis: Facilitated Diffusion

∗ Osmosis is the diffusion of water through a selectively permeable membrane.

∗ Osmosis involves the movement of water molecules from an area of higher concentration to an area of lower concentration.

Osmosis: An Example of Facilitated Diffusion

∗ Isotonic - When the concentration is the same on both sides of the membrane.

How Osmosis Works

∗ Hypertonic - a more concentrated solution (above strength).

∗ Hypotonic = a dilute solution (below strength).

Osmosis http://youtu.be/SrON0nEEWmo

Osmotic Pressure - The net movement of water out of or into a cell exerts a force known as osmotic pressure.

Active Transport - The movement of materials against a concentration difference.

Active Transport

Low concentration of solute particles (stuff) outside of the cell

High concentration of solute particles inside the cell

Potassium

Sodium

Calcium

∗ Endocytosis is the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane.

Endocytosis

∗ Phagocytosis, extensions of cytoplasm surround a particle and package it within a food vacuole. The cell then engulfs it.

Phagocytosis real: http://www.youtube.com/watch?v=BDr44vLNnPY

Endocytosis

Pinocytosis - cells take up liquid from the surrounding environment by forming tiny pockets along the cell membrane.

Endocytosis

Exocytosis - the membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents out of the cell.

Exocytosis

1. Explain the structures involved in cell movement. 2. Which organisms contain a cell wall?3. How does diffusion work? 4. What is homeostasis? 5. How is a tissue defined? 6. Explain the cell theory? 7. What are electron microscopes used for?8. Explain the difference between a prokaryote and a eukaryote.9. What organelles do you find in plant but not in animal cells?

10. What is osmotic pressure? Why is it important?11. Explain the difference between hypotonic, isotonic, and

hypertonic. 12. Be able to locate all of the organelles in a plant and animal cell.

Biology Quiz Review

1. Why are light microscopes important? What about electron microscopes?2. Explain what microtubules and microfilaments used for?3. List the organisms that contain a cell wall.4. How does diffusion effect the concentration of solute particles?5. What is homeostasis? What is a tissue?6. Explain the three main points of the cell theory. 7. Compare and contrast prokaryotes and eukaryotes. 8. Plant organelles vs. animal cell organelles. 9. How does osmotic pressure work with animal cells and plant cells?

10. List and locate all of the plant, animal and prokaryotic cell structures. 11. Define hypotonic, hypertonic, and isotonic. How do cells reaction in these solutions? 12. Compare and contrast active transport, diffusion, and facilitative diffusion. 13. What is a lipid bilayer made up of? Why is it considered semi-permeable?

Test Review

∗ Biology Corner: http://www.biologycorner.com/quizzes/∗ Complete the following sections:∗ Cell Membrane, Cell Parts, Cell Quiz, Cell theory, and

Diffusion & Osmosis.

∗ For each section you complete, provide your score (seen at the end of each quiz).

∗ In addition, for each section copy two multiple choice questions.

Online Quiz Review

● Log in to a computer and click on this box! ● Today’s quiz is titled “Bio_U02_USA_FY17”