How Do We Get Oxygen From the Air Into Our Cells?

Transcription

1 Name: Per: Date How Do We Get Oxygen From the Air Into Our Cells? Diffusion, Osmosis and Active Transport DAY 1 Read and follow the steps below to get started: 1. Go to the following website to learn more about transport across a cell membrane: 2. Once you have opened the website by clicking on the link above, click on the orange box on the right side of the screen that says Download and Launch (keep pressing OK until it opens) 3. Check the box for Anonymous user and press OK 4. This is your home screen for the activity today. Day 1: 1. When you re at the home page, click on the Introduction under Day 1. This will take you to Diffusion, Osmosis, and Active Transport: Introduction. b. Press Run beneath the first simulation on the right. This is just to show you what it would be like if you attached a camera or GoPro to an oxygen gas molecule! c. Answer the following review questions to help set you up for the simulation: i. How do molecules enter and leave cells (name the process): ii. List two gas molecules that enter/leave our cells: iii. List at least one liquid molecule that enter/leave our cells: iv. List at least three solid molecules that enter/leave our cells: d. After you have read the Introduction to Diffusion, scroll down to the Simple Diffusion Example. Follow the instructions to run the simulation to the right.

2 i. Write down your answer from the question in the gray box: After looking at the path taken by several of the red dye molecules, how would you best describe their motion? ii. It is often stated that substances diffuse from areas of high concentration to areas of low concentration. Describe how this works if a molecule can't tell that it is in a region of high concentration and just diffuses randomly through collisions. 2. Go to the bottom of the page and select the demo number 2 in the index. This will take you to Diffusion, Osmosis, and Active Transport: Net Flow From High to Low. (Note that it says respiration which is short for cellular respiration ). c. What are the chances that a molecule will move into or out of the cell? d. Describe the flow of molecules when there is an area of high and low concentration. 3. Go to the bottom of the page and select the demo number 3 in the index. This will take you to Diffusion, Osmosis, and Active Transport: Dynamic Equilibrium.

3 c. What is true of the concentrations when equilibrium has been reached? Draw a snapshot picture at equilibrium and label the molecules and membrane. d. What is true of the rate at which molecules move into and out of the cell at equilibrium? Draw a snapshot picture at equilibrium and specify the rate of movement of the molecules. 4. Go to the bottom of the page and select the demo number 4 in the index. This will take you to Diffusion, Osmosis, and Active Transport: Concentration and Breathing. c. What happens to the oxygen concentration of the cell when you move it to a new environment? d. Explain how a red blood cell delivers oxygen from your lungs to the rest of your body.

4 5. Go to the bottom of the page and select the demo number 5 in the index. This will take you to Diffusion, Osmosis, and Active Transport: Evolving Efficient Breathing. c. Describe what happens when the red blood cell contains hemoglobin: d. Explain how hemoglobin helps transport more oxygen than could normally be done with simple diffusion: STOP: Debrief with class discussion of the following questions: 1. List three factors that affect the motion of molecule into and out of cells, the process known as diffusion? 2. When we sweat from exercise, our body is losing ions through the sweat. How does this affect the flow of ions back into the cells? 3. Using your knowledge of diffusion, explain why red blood cells absorb oxygen in our lungs and release it to the rest of our body? Why not the other way around?

5 Name: Per: Date How Do We Get Oxygen From the Air Into Our Cells? Diffusion, Osmosis and Active Transport DAY 2 Read and follow the steps below to get started: a. Go to the following website to learn more about transport across a cell membrane: b. Once you have opened the website by clicking on the link above, click on the orange box on the right side of the screen that says Download and Launch (keep pressing OK until it opens) c. Check the box for Anonymous user and press OK d. This is your home screen for the activity today. DAY 2: 1. Go to the bottom of the page and select the demo number 6 in the index. This will take you to Diffusion, Osmosis, and Active Transport: The Role of Surface Area. c. How does surface area affect diffusion rates? d. Single-celled organisms absorb everything they need directly through their "skin," their cell membrane. However, you could never get enough oxygen if oxygen could only diffuse through your skin. Explain why it is necessary to have lungs with large surface areas: 2. Go to the bottom of the page and select the demo number 7 in the index. This will take you to Diffusion, Osmosis, and Active Transport: The Porous Membrane.

6 c. Which are the only types of molecules that pass easily through the cell membrane without an aquapore? d. What is true of most naturally occurring pores? 3. Go to the bottom of the page and select the demo number 8 in the index. This will take you to Diffusion, Osmosis, and Active Transport: Osmosis. c. Osmotic pressure is related to salt concentrations (or other dissolved substances) in what way? d. If you want water to flow out of the cell faster than into the cell you should: e. Cells generally stay in equilibrium with their surroundings. What are two ways you know the cell has reached equilibrium? f. Describe the similarities and differences between diffusion and osmosis. 4. Go to the bottom of the page and select the demo number 9 in the index. This will take you to Diffusion, Osmosis, and Active Transport: Making an Electric Potential c. What must be done to get an electric potential (a voltage) across the membrane?

7 d. How can you get the maximum voltage across the cell membrane? 5. Go to the bottom of the page and select the demo number 10 in the index. This will take you to Diffusion, Osmosis, and Active Transport: Active Transport. c. What factor most affects how much chemical energy you start with? d. Describe how the chemical energy in ATP is converted into electric potential energy. 6. Go to the bottom of the page and select the demo number 11 in the index. This will take you to Diffusion, Osmosis, and Active Transport: Summary Questions a. Which best describes the motion of an INDIVIDUAL ion or molecule: b. Describe in as many ways as possible how you know when a system has reached equilibrium: c. Describe what will happen if a cell has an oxygen concentration that is higher outside of the cell compared with inside of the cell (see illustration to the right): d. Describe how surface area affects the speed at which diffusing ions or molecules reach equilibrium across both sides of the surface:

8 e. Which of the following can pass through a cell membrane without a specialized pore: f. If you were to drink salt water from the ocean which has a high concentration of dissolved ions, what would happen? g. Describe how you can make an electric potential occur across a membrane, and how you can maximize this potential energy: STOP: Debrief with class discussion of the following questions: 1. What role does surface area play in diffusion rates and why is the diffusion rate important? 2. Many molecules and even single atom ions can t diffuse easily through the cell membrane. How do they get into and out of cells? 3. All life requires water, and being able to regulate how much water moves into or out of a cell is crucial. What affects the flow of water into and out of cells? 4. Cells frequently need to keep high concentrations of some chemical inside, or they need to keep other chemicals out (low concentration inside). What happens when you actively move ions into or out of a cell? 5. What is the source of energy for actively transporting ions against their equilibrium concentrations