LABS 16 AND 17 REVIEW SHEET Cell Membranes Name: Ella Pledge: I hereby pledge my honor I have neither given nor reicieved any unauthorized aid on this assignment AUTHORIZED AID: You may discuss questions with classmates or other knowledgeable persons before composing your OWN answer or you may use a source and cite it appropriately. Review the following links and use them to answer the questions that follow. If these links don’t immediately open for you, then copy and paste the URL into your browser. Cell Membranes https://www.wiley.com/legacy/college/bo yer/0470003790/animations/membrane_ transport/membrane_transport.htm Membrane Interactive Video https://www.wiley.com/college/pratt/047 1393878/student/animations/membrane_ transport/index.htm Review the following videos and use them to answer the questions that follow: How Diffusion Works How Facilitated Diffusion Works How Osmosis Works Phagocytosis & Lysosomes Use the Biology Online Dictionary to help you answer the following questions. Again, you may need to paste the URL into your browser. Type each of the blue underlined words below into the dictionary search field to help you understand the content. http://www.biology-online.org/dictionary/ 1. Why is the cell membrane called a phospholipids bilayer? because it is 2 layers made up of phopholipids Fluid Mosaic model? because the fluid mosaic model is a model of the membrane 2. What 3 parts is the phospholipid bilayer made of? What is the purpose of each? a. proteins purpose: transporting substances across cell membrane b. 'head' purpose: to protect the sensitive parts inside c. 'tail' purpose: transport 3. Knowing that hydro means water, philic means loving, and phobic means hating, which part of the phospholipid is hydrophilic? headWhich part is hydrophobic? tail a. If all cells are in water and all cells have cytoplasm (mainly composed of water), explain why the membrane must be composed of two layers of phospholipids. the head is only on one end of the phospholipid and the tail is on the other so if there was only one layer than the tail would be exposed to water. there needs to be two layers of phospholipids because the heads have to face outward on both ends because they are not hydrophobic 4. Define Passive Transport: when substances move down their concentration gradients 5. Define diffusion a type of Passive transport: substance moving from a higher concentration to a lower concentraion 6. What three factors affect the movement of molecules by diffusion? a. temperature b. size of molecules c. blockage 7. What is equilibrium (use isotonic in your answer)? equilibrium is the state of molecules being fairly equal on both sides of the cell. an isostonic solution is an example of equilibrium 8. Define Facilitated Diffusion a type of Passive transport: the transport of substances across a membrane from an area of higher concentration to an area of lower concentration with the help of a transport molecule a. Is energy required for facilitated diffusion? no explain substances move along the direction of their concentration gradient b. Are proteins required? yes explain they are required for transport in the phospholipid bilayer c. Do molecules move with or against the concentration gradient? with d. Look at the different types of proteins: channel, antiport, symport. 9. Define Osmosis a type of Passive transport: osmosis is a type of diffusion where water molecules moves from a higher concentration to a lower concentration over a membrane a. Knowing the definitions of hypertonic and hypotonic, which way will water move from hypertonic to hypotonic or hypotonic to hypertonic? hypertonic - hypotonic 10. Define Active transport: when substances move against a concentration gradient a. Why is it necessary? esstional in many biological processes b. Is energy required? yes c. Is a protein? yes d. Do molecules move with or against the concentration gradient? against 11. Define vesicle mediated transport: A cellular transport process in which transported substances are moved in membrane-bounded vesicles a. What is endocytosis? the cell membrane forms a pocket around the target particle b. Give an example of endocytosis. engulfing a bacteria c. What is exocytosis? the cell membrane expells a target particle using a pocket d. Give an example of exocytosis. secretion of enzymes or other substances 12. What is homeostasis? the ability to maintain a internal temperature with an ever changing external enviorment 13. What are some examples of how an organism might maintain homeostasis? human ternal body temperature 14. How would the phospholipid bilayer be involved in maintaining homeostasis? it transports things in and out of the cell so it probaly repells somethings of a higher temperature 15. What are some (at least three) specific types of molecules that are transported across the cell membrane? a. water b. carbon dioxide c. oxygen 16. How are these (at least three) molecules important for maintaining homeostasis in an organism? a. water takes a long time to heat up and cool down b. gas exchange- lungs eliminating CO2 c. gas exchange- oxygen needed for cellular respiration Citation:
