1. The Cell Membrane & Cellular Transport Function of cell membrane Structure of cell membrane Cellular transport

2. All living cells must maintain a balanced environment regardless of internal and external conditions. This process of maintaining the cell’s environment (balance) is called homeostasis. Survival depends on the cell’s ability to maintain the proper conditions within itself. Introduction

3. Functions of the cell Membrane (1). Controls what goes in and out of the cell. * Selective permeability (Semipermeable) describes the cell membrane’s ability to allow some molecules into the cell while keeping others out. Water Cell Membrane

4. allow waste and other products to leave the cell. remove excess amounts of these nutrients when levels get so high that they are harmful. a)allow a steady supply of water, glucose, amino acids, and lipids to come into the cell no matter what the external conditions are. (2). Maintain homeostasis

5. Structure of the Cell Membrane A.The cell membrane is composed of 2 layers of phospholipids back- to-back. Phospholipids are lipids with a phosphate attached to them. The two layers are referred to as the phospholipid bilayer.

6. B.The lipid units that make up the plasma membrane have a: 1.glycerol backbone 2.two fatty acid chains 3.A phosphate group. Glycerol Backbone Two Fatty Acid Chains Phosphate Group

7. Which of the following best describes the cell membrane's mechanism in maintaining homeostasis? A protein synthesis B selective permeability C fluid composition D structural protein attachment Question 1

8. The answer is B. Selective permeability is the process in which the membrane allows some molecules to pass through, while keeping others out.

9. Cellular Transport 2 Types Passive Transport Active Transport

10. Passive Transport cell DOES NOT use energy - molecules are being moved from high concentration to low concentration Three Types of Passive Transport: 1.Diffusion 2.Facilitated Diffusion 3.Osmosis high low Weeee! !!

11. 3 Types of Passive Transport 1.Diffusion – movement of most molecules (such as sugar, oxygen etc.) across the cell membrane from high to low. 2.Facilitated Diffusion – diffusion of larger molecules with the help of transport proteins but NOT requiring energy from the cell. 3.Osmosis (diffusion) movement of water across the cell membrane from high to low.

13. Animation : How Diffusion Works

14. Importance of Diffusion to Cells and Humans: Cellular Respiration Alveoli of Lungs Capillaries Red blood cells Time-released medications

15. Rate of diffusion - depends on temperature and size of molecules. -molecules diffuse faster at higher temperatures then lower temperatures. -- small molecules diffuse faster than large molecules

16. 2.Facilitated Diffusion type of passive transport which uses the help of transport proteins. Protein Channels assist (help) molecules such as glucose, amino acids, ions, etc. across the cell membrane WITHOUT the use of the cell’s ENERGY

17. Animation - How Facilitated Diffusion Works

18. Importance of Facilitated Diffusion to Cells and Humans: Cells obtain food to carry out cellular respiration Neurons can communicate Small intestines cells transport food to the blood stream Muscle cells contract

19. 3.Osmosis Osmosis water a)The diffusion of water across selectively permeable membranes. b)The water moves from a [high]  [low] concentration. http://www.bbc.co.uk/education/asguru/biology/01cellbiology/05pathways/10osmosis/index.shtml

20. Animation: How Osmosis Works

21. Importance of Osmosis on Cells and Humans: Cells remove water produced by cellular respiration Large intestines cells transport water to the bloodstream Kidney cells form urine

22. What makes up a Solution? * Solvent – it is what does the dissolving (usually water) * Solute – it is what is being dissolved (sugar, salt etc.) In the solution below, which is the solute? Which is the solvent? NaCl (salt)+ H 2 0  saltwater Solute SolventSolution

23. 1)Hypertonic solution A solution with a greater solute concentration compared to another solution. 5% NaCl 95% H 2 O solution 3% NaCl 97% H 2 O Red Blood Cell c)Osmosis c)Osmosis occurs in 3 types of solutions. Water moves OUT!

24. 2)Hypotonic solution A solution with a lower solute concentration compared to another solution. 3% Na 97% H 2 O Red Blood Cell 1% Na 99% H 2 O solution c)Osmosis c)Osmosis occurs in 3 types of solutions. Water moves IN!

25. 3)Isotonic solution A solution with an equal solute concentration compared to another solution. 3% Na 97% H 2 O Red Blood Cell 3% Na 97% H 2 O solution c)Osmosis c)Osmosis occurs in 3 types of solutions. Water moves IN & OUT @ same rate!

26. Hypotonic  Hypertonic What happens to blood cells placed in various solutions? Swell & burst Stay the same Shrivel

27. f.Osmosis in Plant Cells

28. Active Transport Cell DOES use energy that is stored in ATP (energy storing molecule) to transport substances across the cell membrane from an area of LOW concentration to an area of HIGH concentration by using one of the following methods: 1.Protein Pumps 2.Endocytosis 3.Exocytosis high low This is gonna be hard work!! ACTIVE TRANSPORT

29. Importance of Active Transport Gets rid of unwanted molecules such as sodium from urine in the kidneys Maintains internal conditions that are different from the environment Controls cellular pH levels

30. Types of Active Transport 1. Protein Pumps - transport proteins that require energy to do work Example: Sodium / Potassium Pumps are important in nerve responses. Sodium Potassium Pumps Sodium Potassium Pumps (Active Transport using proteins) Protein changes shape to move molecules: this requires energy!

31. Animation How the Sodium-Potassium Pump Works

32. 2. Endocytosis: “cell eating” the taking of bulky material into a cell – Uses energy – Cell membrane surrounds food particle to engulf. – forms food vacuole & digests food – Ex: This is how white blood cells eat bacteria!

33. 3. Exocytosis: Forces material out of cell in bulk – membrane surrounds the material and fuses with cell membrane – Cell changes shape – requires energy – EX: Hormones or wastes released from cell Endocytosis & Exocytosis Endocytosis & Exocytosis animations

34. Pinocytosis “Cellular Drinking” – engulfing liquids and small molecules dissolved in liquids; unspecific what enters. Ex. Intestinal cells, Kidney cells, Plant root cells