CELL MEMBRANE AND CELL TRANSPORT NOTES

1. CELL MEMBRANE AND CELL TRANSPORT NOTES

2. Standard Cell Biology • 1. a. Students know cells are enclosed within semipermeable membranes that regulate their interaction with their surroundings. • https://www.youtube.com/watch?v=owEgqrq51zY

3. What is the cell membrane? The cell membrane regulates what enters and leaves the cell and also provides protection and support.

4. The structure of the cell membrane • The cell membrane consists of a lipid bilayer (lipid = fat; bi=2)plus proteins that straddle the bilayer. Attached to the proteins are carbohydrates. • Many of these proteins are channels and pumps that allow substances through or not!

5. Draw the cell membrane

6. Cell Membrane Video • https://www.youtube.com/watch?v=S7CJ7xZOjm0

7. You should be able to answer these questions: • Describe the structure of the cell membrane. • How do molecules get into and out of the cell? • What is selective permeability? • What is diffusion and how does it work? • What is facilitated diffusion and how does it work? • What is active transport and how does it work? • What is osmosis and how does it work? • What is the function of transport proteins?

8. Transport through the Cell Membrane

9. Cell membranes are selectively permeable (semipermeable). • Permeable- ability to pass through a membrane • Impermeable- can’t pass through • Selectively Permeable (semipermeable)- some things can pass through and some can’t

10. Copy the chart into your notes

11. Transport Through the Membrane Passive Transport: • Simple Diffusion • Facilitated Diffusion Active Transport

12. Simple Diffusion • No transport protein used • Movement WITH the concentration gradient (high to low) • No additional cell energy required • PASSIVE • Examples: water, carbon dioxide and oxygen

14. Solution- a liquid with one or more substances dissolved in it • Solvent- the liquid that the solute is dissolved in • Solute- the substance dissolved in a solution • Concentration- how strong it is  the solute/volume (percentage)

15. Think of living cells like little bags of solutions surrounded by a semipermeable membrane!For the cell to survive, the concentration of solutes must stay within a safe range to maintain homeostasis.

16. Concentration Gradient- when there is a difference in concentrations • High concentration: more particles • Low concentration: fewer particles • In diffusion, particles move from high to low concentration to reach an equal concentration (equilibrium) on each side.

19. Facilitated Diffusion • Transport protein used: carrier protein or channel protein • Movement WITH the concentration gradient (high to low) • No additional cell energy required • PASSIVE • Example: Glucose molecules

21. Carrier Proteins

22. Channel Proteins

23. Passive Transport: Facilitated Diffusion • https://www.youtube.com/watch?v=vKGN_Zhz8AY

24. Active Transport • Transport protein used: carrier protein • Movement AGAINST the concentration gradient (low to high) • Additional cell energy required • ACTIVE • Example: Sodium-Potassium Pump: pumps Na+ ions out of cell and K+ ions into cell

26. Active Transport

27. Active Transport • https://www.youtube.com/watch?v=yz7EHJFDEJs

29. Other Types of Active Transport • Endocytosis – the process of taking material into the cell by folding in pockets of the cell membrane into pouches called vesicles • Phagocytosis – endocytosis involving large solid particles • Pinocytosis – endocytosis involving liquid • Exocytosis – the process of removing material out of the cell where vesicles merge with the cell membrane to release contents

30. Endocytosis and Exocytosis • https://www.youtube.com/watch?v=qpw2p1x9Cic

31. Osmosis- the diffusion of water • No transport protein used • With the concentration gradient (high to low) • No additional cell energy required • Passive

32. Concentration Strength • Isotonic – the solution and the cell have the same concentration strength • Hypotonic – the solution has a lower concentration than the cell • Hypertonic – the solution has a higher concentration strength than the cell

33. Osmotic Pressure • Osmotic Pressure is the pressure that water exerts on the hypertonic side of a selectively permeable membrane. • It can be problematic for living cells because they can burst from over-inflation with water or shrivel up from loss of water.

35. Red Blood Cells in a Hypertonic Solution • https://www.youtube.com/watch?v=OYoaLzobQmk

37. Plants and Osmosis

38. Applications of Osmosis • Water overdose/intoxication • High concentration of fertilizer kills plants • Water enters the roots of plants • Why drinking salt water can kill you • Why putting salt on a slug or snail kills it • How dialysis machines work • The preservation of foods in salt brines (olives, fish vegetables)  kills bacteria • Refresh wilted salad greens by putting in water

39. Cell Quiz • What are two differences between prokaryotes and eukaryotes? • An animal cell is a prokaryotic/eukaryotic cell. (circle the correct answer) • When preparing a wet mount, the cover slip should be put on at an angle to avoid ______. • The ______ contains the DNA and controls the cell. • Diffusion is the movement of molecules from a ______ to a _______ concentration. • If a cell has 95% water and it is placed in a hypertonic solution, water will move out of/into the cell. (circle the correct answer) • _________ are where photosynthesis occurs in plant cells. • A bacteria is a prokaryotic/eukaryotic cell. (circle the correct answer) • On high power, more/less of the cell can be seen. circle the correct answer) • What two things happen to an image when viewed under a microscope? • Choose and explain one of the following: endocytosis, phagocytosis, pinocytosis, or exocytosis.