Chapter 4: Cells and Their Environment

1. Chapter 4:Cells and Their Environment

2. Diffusion • Cell membrane is composed of… • Phospholipid bi-layer • Proteins distributed • Selectively permeable… • Specific items are allowed to enter and exit the cell • These two items are very important for a cell to maintain its homeostasis • Why???

3. Section 4-1: Passive Transport(Random motion and concentration) • Controlling the movement of substances into and out of the cell • Passive Transport (break it down) • Movement of particles across cell membrane that does not require energy to do so • Items do not randomly enter or exit the cell membrane– • homeostasis would never be maintained in this case

4. Random motion and concentration continued • Concentration gradient (necessary) • A difference in concentration of a substance • High to low • Example: Room filled with balls • Does not require energy (goes with the flow) • Equilibrium • Concentration of substance is equal throughout a space

5. Movement of substances • Diffusion • Random motion of particles of a substance from high to low concentration • Example: Room full of balloons • Ions and molecules are small particles that break up and dissolve in cytoplasm and fluid outside of the cells • Can a molecule or ion pass across the cell membrane? • If yes, then what must be necessary for this to occur?

6. Brief Polarity Review • Polar vs. Non-Polar molecules • Polar = dissolves • Non-polar = does not dissolve • What about ions such as Cl- and Na+? • What about lipids such as waxes and fats? • Phospholipid bi-layer has a non polar interior • Repels ions and most polar molecules • Very small molecules, non polar molecules, and uncharged molecules diffuse

7. Helpers in the Cell Membrane Ions and polar molecules are necessary for life. Therefore we need them to be able to get into our cells. How are they going to get inside our cells if they can not diffuse through the cell membrane due to non-polar lipids repelling them?

9. Facilitated Diffusion • Similar to simple diffusion, but aided by integral proteins and electrochemical gradients • Ion Channel • Doughnut-shaped transport protein with a polar pore through which ions can pass • Neurons and Muscle cells • **Electrical gradient** • Carrier proteins • Bind to the ion or molecule that’s normally to large too diffuse through the membrane, then is transported through the membrane and released

11. Real Life Biology • Passive transport: carbon dioxide diffusion • Facilitated Transport

12. Question 1 What type of protein binds to the ion or molecule that’s normally too large to diffuse through the membrane, then transports it through the membrane to be released? • Ion Channel • Receptor • Carrier • Pump

13. Question 2 Facilitated transport is necessary when… • The molecule is too large, polar, or charged • The molecule is too large, non polar, or uncharged • The molecule is too small, polar, or uncharged • The molecule is too small, polar, or charged

14. Question 3: Diffusion is most accurately defined as _____________________. A. the active transport of materials across a cell membrane. B. the facilitated movement of molecules across a permeable membrane. C. the net movement of particles from where they are more concentrated to where they are less concentrated. D. molecules moving randomly in various directions. E. molecules moving in one direction only.

15. Question 4: Passive transport means that a. some particles enter the cell while others do not. b. proteins selectively allow certain small molecules out of the cell. c. oxygen and carbon dioxide diffuse through the plasma membrane in the presence of phosphates. d. no energy is expended by the cell as particles move in and out of the cell. e. proteins move water into the cell.

16. Question 5: Small polar molecules diffuse into and out of the cell through a process called a. facilitated transport. b. exocytosis. c. active transport. d. endocytosis. e. equilibrium.

17. Question of the Day • Name and describe the two types of passive transport we went over in yesterday’s class.

18. Active transport • The transport of a substance across the cell membrane against its concentration gradient which requires __________ • Some molecules our cells need might lack a _______ concentration outside of the cell and force the molecules out even though they are necessary • Energy currency used in cells _________ Energy High ATP

19. Sodium Potassium Pump 3 • Transports ____ sodium ions (Na+) out of a cell and ____ potassium ions (K+) into the cell • Normal concentrations of each: • Na+ = outside cell = needs to move out of the cell • K+ = Inside cell = needs to move in the cell • Against concentration gradient therefore it requires ___________ in the form of ATP 2 Energy

20. 4 Step Process: • Step 1 • Three sodium ions inside the cell bind to the sodium potassium pump. ______________ group is removed from ATP and also binds to the pump • Step 2 • Pump changes shape, transporting the three sodium ions cross the cell membrane and __________ outside of the cell phosphate release

21. 4 Steps continued • Step 3 • The __________ is now exposed on the surface of the cell. Two potassium ions outside the cell bind to the pump. The ___________ group is released changing the _________ of the pump. • Step 4 • The pump is exposed to the inside of the cell. Two ____________ ions are transported across the cell membrane and are released ____________ the cell. The pump is ready to bind more sodium ions pump phosphate shape potassium inside

24. Vesicle movement carrier • Substances exist that are larger than will fit through even our _______ proteins • In this case the __________ will deposit theses polysaccharides or proteins using the following two processes. • Endocytosis • Movement of substance _____ a cell by a vesicle • Exocytosis • The movement of a substance by a vesicle ______ of a cell • Nerve cells, proteins, glandular cells vesicle into out

27. Real Life Biology • Endocytosis: white blood cells, ameoba1and 2 • Exocytosis: paramecium • Receptor proteins: neurotransmitters • Second messenger: Hormones are a type of steroid. Steroids are classified as Lipids. All regulate the endocrine system.

28. Question 1: Which of the following functions does active transport perform in a cell? A. packaging proteins for export from the cell  B. distributing enzymes throughout the cytoplasm C. moving substances against a concentration gradient  D. equalizing the concentration of water inside and outside the cell

29. Question 2: The diagram below illustrates how plant root cells take in mineral ions from the surrounding soil. Which of the following processes is illustrated? A. active transport  B. diffusion  C. osmosis  D. passive filtration

30. Receptor Proteins signal • A protein that binds to a specific ________ molecule, enabling the cell to respond to the __________ molecule • Communication • 3 functions • _______________  permeability (open/close) • Second Messengers • Act as signal molecule in the cytoplasm • Amplification • Trigger • Enzyme action signal Controls

31. Activator 11/19/13: • Pass in your diffusion lab and Osmosis graphic organizer to the homework bin on Ms. Resendes desk • Pass in any late homework due last Friday that you did with a teacher after school to the homework bin. • Answer the following 3 questions on scrap paper 1. Why are fresh vegetables sprinkled with water at markets? 2. Roads are sometimes salted to melt ice. What does this salting do to the plants along roadsides & why? 3. How does the food you absorb in your microvilli get to each and every cell in your body? • Organize any work passed out into your binder.

32. Water Diffusion • The diffusion of water is different than that of molecules and ions • Keep in mind when a substance such as salt dissolves in water the water molecules “cling or grab onto” the ions (such as salt’s Na and Cl) and are not free to grab onto anything else • Osmosis • Diffusion of water through a selectively permeable membrane • If no gradient, which way will it move….

33. Osmosis Chart

36. Question 1 If outside the cell there is a higher free water molecule concentration than in the cytoplasm the cell will swell, which of the following words explains the type of situation. • Osmosis • Hypotonic • Hypertonic • Isotonic

37. Question 2 The diffusion of water through a selectively permeable membrane is known as… • Diffusion • Active Transport • Hypertonic • Osmosis

38. Question 3 If there is the same free water molecule concentration outside the cell as inside the cytoplasm, this situation is called… • Osmosis • Hypotonic • Hypertonic • Isotonic

39. Question 4: If an animal cell is placed in distilled water, it will swell and burst. The bursting of the cell is a result of which biological process? A. active transport  B. enzyme activity C. osmosis  D. respiration

40. Question 5: Which of the diagrams below best represents the net movement of molecules in osmosis? A.  B. C. D.