Cell Transport Notes Key PDF

# Unit 3: All Living Things Exchange Materials with their Environment ## How do Materials Cross the Cell Membrane? - Cells of all living things require molecules from their environment for survival. - Cells need macromolecules (like carbs, lipids, proteins). - Cells rely on digestion and enzyme-en...

# Unit 3: All Living Things Exchange Materials with their Environment ## How do Materials Cross the Cell Membrane? - Cells of all living things require molecules from their environment for survival. - Cells need macromolecules (like carbs, lipids, proteins). - Cells rely on digestion and enzyme-enhanced catabolic reactions to break down food into smaller components. - Cells produce molecules (waste, hormones, proteins, enzymes) that need to be transported outside of the cell. - Cells are designed to allow for the exchange of materials. - **Question:** What would happen if our cells could not exchange materials with their environment? ## I. FIRST - Discover: How do MOLECULES move? **Experiment:** 1. Fill 4 test tubes with 40mL of water each. 2. Complete each experiment below and write down your observations. **Part A:** - Place 1 drop of food dye in test tube #1. **Part B:** - Place 4 drops of food dye in test tube #2. **Part C:** - Place test tube #3 in ice water, wait 5 minutes, and add 1 drop of food dye. **Part D:** - Place test tube #4 in warm water, wait 5 minutes, and add 1 drop of food dye. **Observations:** 1. **Describe the difference between test tube #1 and #2.** Suggest a reason for this difference. - **Answer:** More food dye in test tube #2 represents a higher concentration of molecules. 2. **Describe the difference between test tube #3 and #4.** Suggest a reason for this difference. - **Answer:** Temperature of water to show how temperature changes diffusion. **Read This!** - When 1 or more substances are dissolved in water, a solution is created. - Solutions have 2 parts: - **Solvent:** the water - **Solute:** whatever is dissolved inside the water. **Examples:** | Solution | Solute | Solvent | |---|---|---| | Food Dye + Water | Food Dye | Water | | Sugar + Water | Sugar | Water | ## II. What is DIFFUSION? **Read This!** - All molecules in a liquid or gas are constantly randomly moving, which is maintained through constant collisions with other molecules and with the sides of the container. - **Concentration:** The measurement of the amount of solute in a solvent. - Adding 4 drops of food dye to water creates a solution with higher concentration than adding 1 drop of food dye to water. - Higher concentration means there are MORE solute molecules moving in an area and therefore the potential for more collisions between molecules. **Experiment:** 1. Go to explorelearning.com. 2. Click the Logins button at the top right of the page and then click GIZMOS in blue. 3. Type in your student username. 4. The purple molecule (X) is a solute dissolved in water. - **a. Where is the concentration of X the highest?** (Side A / Side B) - **b. Where is the concentration of X the lowest?** (Side A / Side B) 5. Click on 'bar chart' so your view looks like the image above. Click the PLAY button. 6. **Describe the movement of the solute X molecules - what happens over time?** 7. After about 200 seconds, what do you notice about the number of solute X molecules in region A compared to the number of particles in region B? 8. **Do the molecules ever stop moving? Why or why not?** **Read This!** - When there is a difference in concentration of molecules between 2 areas, diffusion occurs. - Diffusion occurs because as molecules collide, they move apart which makes the molecules spread out or move from an area of high concentration (region A) to an area of low concentration (region B). - **Equilibrium:** When there is NO difference in the concentration between 2 areas, equilibrium has been reached and therefore no more NET movement in any particular direction (the molecules move randomly in ALL directions) which means no more diffusion. - **Temperature is measured on the Kelvin scale.** - 0 K represents absolute zero, the coldest possible temperature. - Water freezes at 273.15 K (0 °C) - Water boils at 373.15 K (100 °C) **Experiment:** 1. Click PAUSE & RESET and TABLE. 2. Perform each experiment below - Click PAUSE when x in A first reaches 55% or below. Record this time to reach equilibrium in the table below. RESET for each new experiment. | Starting Amount of X in side A | TEMPERATURE | TIME to reach EQUILIBRIUM | |---|---|---| | 50 | 300 K | | | 100 | 300 K | | | 50 | 100 K | | | 50 | 600 K | | **Analysis:** 12. **Compare #1 & #2:** Explain how increasing concentration of solute impacts the time to reach equilibrium. 13. **Compare #3 & #4:** Explain why increasing temperature impacts the time to reach equilibrium. 14. **Predict, with a reason:** How would changing the PARTICLE MASS impact the time to reach equilibrium? ## III. How do Materials DIFFUSE across the Cell Membrane? **Can all materials move easily across the membrane?** **Experiment A: Modeling Cell Membranes:** **"Cell 1"** - Tap water in cell - Food dye environment **"Cell 2"** - Glucose & water in cell - Tap water environment **"Cell 3"** - Starch & water in cell - Tap water environment **Observations:** - **"Cell 1":** - Originally the food dye molecules were only outside the cell. - Did the food dye molecules diffuse into the "cell"? **Yes!** - How do you know? **The solution turned blue.** - **"Cell 2":** - Use a glucose test strip to test the water in the test tube. - Originally glucose was only inside the cell - Did glucose diffuse out of the "cell"? **Yes!** - How do you know? **The glucose strip showed a positive result for glucose in the solution.** - **"Cell 3":** - Use a drop of iodine to test the water in the test tube. - Originally starch was only inside the cell - Did starch diffuse out of the "cell"? **No!** - How do you know? **The iodine did not turn purple/black outside of the "cell".** **Read This!** - The (plasma) membrane regulates what enters and leaves the cell. - This means the plasma membrane is selectively or semi-permeable. - When a solute is able to cross a membrane, we say the membrane is permeable to that solute. **Analysis:** 1. **a. The membrane in these experiments was permeable to which solute(s)?** - **Answer:** Food dye & glucose 2. **b. The membrane in these experiments was impermeable to which solute(s)?** - **Answer:** Starch 3. Starch & glucose are both carbohydrates. Knowing what you know about the molecular size of starch vs. glucose, explain the difference in ability to cross the "cell membrane". - **Answer:** Smaller molecule (glucose) could cross, but larger molecule (starch) could not. 4. Suggest why it would be BAD if our membranes were permeable to everything (instead of selective). ## IV. ZOOMING IN on the Plasma Membrane! - The plasma membrane is made up of phospholipids. **Image:** - Show an individual cell. - The cell membrane is labeled, showing the phospholipid bilayer. - Arrows indicate the movement of molecules into and out of the cell. - Arrows are passing in between the phospholipids AND through "proteins." **Analysis:** 1. **Suggest what the arrows in the diagram represent.** How do you know? - **Answer:** movement of molecules into or out of the cell. 2. **Most of the plasma membrane is made up of which macromolecule?** How do you know? - **Answer:** phospholipids 3. **a) What other macromolecule do you see in the membrane?** - **Answer:** proteins 4. **b) What do you see this macromolecule helping with?** - **Answer:** cell transport 5. **CHALLENGE:** Arrows are passing in between the phospholipids AND through "proteins. Suggest a reason why some materials might travel in between phospholipids and others might travel through proteins. What makes you say this?' ## V. Other Forms of Transport **Read This!** - Some molecules, such as glucose or ions, are too big to squeeze between the phospholipids (like the STARCH in our mini-experiment) and therefore need to travel through transport proteins. - **Passive transport:** Diffusion is called passive transport because it does NOT require the cell to use energy. - **Active transport:** Active transport requires the cell to use some ENERGY (ATP) because it is moving substances from low to high concentration. **A. Comparing Active and Passive Transport (use ✓ to fill in the table):** **Image:** - A cell. - Arrows indicate the movement of molecules into and out of the cell. - Different types of transport are labeled: diffusion, facilitated diffusion, active transport, passive transport. | | Active Transport | Passive Transport | Facilitated Diffusion | |---|---|---|---| | Requires energy (ATP) input from the cell | ✓ | | ✓ | | Solute molecules move from high to low concentration | ✓ | ✓ | ✓ | | Solute molecules move low to high concentration | ✓ | | | | Always uses transport proteins | ✓ | | ✓ | | Solute molecules pass between the phospholipids | ✓ | ✓ | | ## VI. Movement of VERY LARGE materials via vesicle formation **A. Exocytosis** - Movement of large/lots of molecules OUT of a cell by a vesicle merging with the membrane (exocytosis = exit). **B. Endocytosis** - Movement of large/lots of molecules INTO a cell by a `bubble` of membrane forming (vesicle) (endocytosis = enter). **Image:** - Different types of vesicles forming within a cell are shown. - Both exocytosis and phagocytosis are shown. **Read This!** - Diffusion of OXYGEN & CARBON DIOXIDE in the body. - These are just a few places in the body where diffusion occurs. - The first picture shows exchange of gases between the lungs and our blood.. - The 2nd picture shows the exchange of gases between the blood and our cells. **Images:** 1. **Image 1:** Shows the gas exchange within the lungs with the blood. 2. **Image 2:** Shows the gas exchange between the blood and the cells. **Additional Images:** 1. **Active Transport of GLUCOSE from intestines into blood:** - Shows the movement of glucose from the intestines to the blood. - The intestinal cell is labeled, along with the blood vessel. - An arrow indicates the direction of movement, with the words "active transport" placed below. 2. **Endocytosis of bacteria by white blood cells:** - Shows a white blood cell engulfing bacteria via endocytosis. - The white blood cell is labeled, along with the bacterial cell. - An arrow indicates the direction of movement, with the words "endocytosis" placed below. ## VIII. Discovering how WATER moves in & out of cells **Sketch & DESCRIBE what you SEE in each scenario.** **Image:** - **4 different scenarios are shown:** - Potato slices in salt water = HYPERTONIC environment - Potato slices in fresh water = HYPOTONIC environment - Egg in corn syrup = HYPERTONIC environment - Egg in fresh water = HYPOTONIC environment - **Labels:** - "Potato slice is 'wiggly'" - "Potato slice is rigid" - "Egg is smaller + wrinkly" - "Egg is larger + 'bouncy'" **Analysis:** **HYPERTONIC ENVIRONMENTS** contain a relatively HIGH amount of solute. 1. **Suggest - Did the potato & egg slice LOSE or GAIN water when placed in hypertonic solutions?** What makes you say that? - **Answer:** Lose water - they are smaller & wrinklier/floppier than the hypotonic egg + potato 2. Think of a situation in your everyday life where adding lots of salt or sugar causes the result you saw with the potatoes & egg placed in hypertonic solutions. Write it here: - **Answer:** If you eat lots of salty food you may feel very thirsty as your cells lose water. **HYPOTONIC ENVIRONMENTS** contain a relatively LOW amount of solute. 1. **Suggest - Did the potato & egg slice LOSE or GAIN water when placed in hypotonic solutions?** What makes you say that? - **Answer:** Gain water - they are larger/more rigid than the hyper tonic counterparts 2. Think of a situation in your everyday life where adding lots of pure water causes the result you saw with the potatoes & egg placed in hypotonic solutions. Write it here: - **Answer:** Water on produce in the grocery store to make it look (juicy & delicious!). **Osmosis:** - The net diffusion of WATER across a membrane. - Water molecules move from an area of relatively *(low/high)* concentration of solute to an area of relatively *(low/high)* high concentration of solute. ## Model 5: **Image:** - 3 cells are shown: - 1 in hypotonic solution, with the label **Lysis** - 1 in isotonic solution, with the label **Normal** - 1 in hypertonic solution, with the label **Shriveled**. - Arrows indicate the movement of water into or out of the cells. **Analysis:** 1. **Consider the cell that is in HYPERTONIC solution (with a HIGH concentration of solute & low amount of water):** - **a. When a cell is placed in a hypertonic environment, the cell will mostly (lose / gain) water.** - **Answer:** lose - **b. Describe what is happening to the animal cell shape when placed in hypertonic solution.** - **Answer:** Animal cell becomes shriveled (smaller + wrinkly) when placed in hypertonic solutions. 2. **Consider cell that is in HYPOTONIC solution (with a LOW concentration of solute & high among of water):** - **a. When a cell is placed in a hypotonic environment, the cell will mostly (lose / gain) water.** - **Answer:** gain - **b. Describe what is happening to the animal cell when placed in hypotonic solution.** - **Answer:** Animal cell swells/grows & can even "pop" (lysis) - **c. What structure on the plant cell do you think would prevent lysis from occurring in a hypotonic solution?** - **Answer:** Cell Wall! Provides structure & helps prevent lysis. 3. **Consider cell that is in ISOTONIC solution:** - **a. What is happening to the animal cell in terms of water loss/gain?** - **Answer:** water is both entering and exiting the cell; no net movement in one direction, only random molecular movement - **b. Define the term ISOTONIC solution.** - **Answer:** Has the same concentration as the cell ## Cell Transport Test Review/Study Guide 1. **Label the structures A & B on the cell membrane diagram at the right.** - **Terms to use:** Lipid bilayer, Transport protein 2. **What is the function of the structures labeled B?** **Match the term with its correct description:** a. energy b. facilitated diffusion c. endocytosis d. selectively permeable e. active transport f. exocytosis g. passive transport h. diffusion i. osmosis j. transport protein 1. __j__ Protein that provides a channel-like opening in the plasma membrane through which molecules / materials can diffuse 2. __a__ Is used during active transport but not passive transport 3. __c__ Process by which a cell takes IN large material by forming a vesicle (or pocket) around it 4. __g/h__ Solute movement from an area of higher concentration to an area of lower concentration 5. __f__ A vesicle (pocket) fuses (becomes a part of) the cell membrane and the contents are released out of the cell 6. __b__ A form of passive transport that uses transport proteins 7. __e__ Solute movement from an area of lower concentration to an area of higher concentration 8. __i__ The diffusion of water through a cell membrane 9. __g/h__ The movement of substances through the cell membrane without the use of energy 10. __d__ Cell membranes are _______ because they allow only some materials to pass through the lipid bilayer, but not others. ## Image: - Shows a cell membrane. - Labels include: - Lipid Bilayer - Transport Protein - Extracellular fluid - Cytoplasm - Time **Analysis:** 11. **Explain what is happening in the picture at the right.** USE these terms in your explanation: High concentration, low concentration, diffusion, permeable, net movement. - **Answer:** In image #1, solute molecules have a high concentration outside of the cell (extracellular) and a low concentration inside the cell (in cytoplasm). As the lipid bilayer/membrane is permeable to the solute, there is net movement into the cell. By image #3 the concentration of solute inside and outside are at equilibrium. This net movement of solute from high to low is diffusion. 12. **Describe equilibrium.** - **Answer:** Concentration of solute is equally distributed (no concentration gradient/regions of high or low). 13. What are the THREE types of PASSIVE transport (don't require energy)? - **Answer:** 1. Simple Diffusion 2. Facilitated Diffusion 3. Osmosis 14. **Identify which type of transport is shown in each image below. Explain how you know.** **Images:** **A.** A cell is surrounded by water molecules. - **Answer:** Osmosis! Water (H2O) is exiting this cell. **B.** A cell with labeled phospholipids. - **Answer:** (Simple) Diffusion! Solute molecules are moving high to low through phospholipids. **C.** A cell surrounded by labeled solute molecules. - **Answer:** Active transport! Energy (ATP) required, + going low to high **D.** A cell with labeled transport protein and solute molecules. - **Answer:** Facilitated diffusion! Solute moving high to low through transport proteins **E.** A cell with labeled plasma membrane and vesicle. - **Answer:** Exocytosis! Movement out of the cell via a vesicle. 15. **Compare and Contrast facilitated diffusion and active transport.** - **Answer:** Both facilitated diffusion and active transport require transport. proteins. Both move solute molecules. Facilitated diffusion is passive while active transport requires ATP. Facilitated diffusion moves with the concentration gradient (high to low) and Active transport moves against (low to high) 16. **Compare and Contrast diffusion and facilitated diffusion.** - **Answer:** Both diffusion & Facilitated diffusion move solutes passively with the concentration gradient (high to low). In diffusion, molecules move directly through phospholipids, while in facilitated diffusion, they move through transport proteins. 17. **Compare and Contrast osmosis and simple diffusion.** - **Answer:** Osmosis & simple diffusion are both passive processes where molecules move directly across phospholipids. Osmosis is the movement of water (solvent) while diffusion is the movement of solute. 18. **Complete the table by placing a ✓ in the correct column for each statement:** | Statement | Isotonic solution AROUND the cell | Hypotonic solution (lower solute) AROUND the cell | Hypertonic solution (higher solute) AROUND | |---|---|---|---| | Causes a cell to swell / get bigger | | ✓ | | | Doesn't change the shape of a cell | ✓ | | | | Causes osmosis | | | ✓ | | Causes a cell to shrink / get smaller | | | ✓ | 19. **If a cell is placed in a hypertonic solution, where would the water move?** **Out** __WHY?__ - **Answer:** Higher concentration of solute outside of the cell. 20. **If a cell is placed in a hypotonic solution, where would the water move?** **In** __WHY?__ - **Answer:** Higher concentration of solute inside of the cell, will be diluted by water (a solvent) ## Extension Questions about Osmosis **Use VOCAB words: hypotonic, hypertonic, and isotonic where applicable.** 21. Using the concept of osmosis, explain why water is sprayed over produce in a grocery store. How might this change the appearance of the produce, and why would this change be desirable? (Circle the correct words in the sentence to help guide you in HOW the answers to these questions should be written) - **Answer:** Water sprayed on the veggies is **(hypertonic / hypotonic)** and therefore the cells **(gain/lose)** water, making them appear very plump and juicy. The pure water sprayed on the produce is **hypotonic** compared to plant cells (which are full of solute). Water will enter the cells via osmosis to attempt to reach **equilibrium**. 22. If you were stranded on the ocean, why would drinking the salty ocean water NOT be a good idea? - **Answer:** Salt water has a very high concentration of solute. This makes salt water **hypertonic** compared to our cells, so if we drank it, water would leave our cells (travel from lower solute concentration to higher solute concentration). 23. A common technique for getting rid of slugs in your garden is to add salt water to your soil. Using your knowledge of osmosis, explain why adding salt water to the soil kills the slugs. - **Answer:** Adding salt to slugs makes the surface of their body **hypertonic**, and therefore water leaves their cells via osmosis. 24. Using your knowledge of osmosis, explain why the egg placed in corn syrup has these results. - **Answer:** The corn syrup egg decreased in mass because it was in a **hypertonic** solution. This caused water to exit the egg and therefore a decrease in mass was observed. 25. Using your knowledge of osmosis, explain why the egg placed in water has these results. - **Answer:** The water egg gained mass because it was in a **hypotonic** solution, so water entered via osmosis. ## Graph Interpretation Practice: **Image:** - A graph with two lines: - One labeled "Facilitated Diffusion" - One labeled "Simple diffusion" - The x-axis is labeled "*Solute Conc Concentration outside cell*" - The y-axis is labeled "*Rate of Transport*" **Analysis:** 1. **Describe how increasing solute concentration outside a cell changes the rate of facilitated diffusion.** - **Answer:** Increasing solute concentration results in **logarithmic increase** in the rate of facilitated diffusion. 2. **Compare and contrast the rate of diffusion for facilitated diffusion vs. simple diffusion.** - **Answer:** Both show an increase in the rate of solute movement as concentration increases. Facilitated increases quickly and then levels out, while simple increases linearly. 3. **Based on your knowledge of diffusion vs. facilitated diffusion, suggest why there is a difference between the rate of transport for these two types of diffusion.** - **Answer:** Because facilitated diffusion uses transport proteins, molecules can move more quickly across the membrane. ## What to expect on the cell transport test: - 20 points - 11 pts. matching & multiple choice/rest is short answer - **Topics:** - Terminology (solute, solvent, diffusion, hypertonic, diffusion, active transport, etc.) - Membrane structure (lipids & proteins) - Pictures of processes - be able to recognize and explain what is happening in a picture of diffusion, facilitated diffusion, active transport, endocytosis, exocytosis - Osmosis "story problem" - Compare and contrast different types of transport - Graph interpretation