AP Biology Unit 2

• What is passive transport?

  The transport of materials across the membrane that requires no energy input. The molecules go with the concentration gradient.
• How would a large, polar/charged molecule transport across the membrane (ions)?

  active transport
• What is required for active transport?

  An input of energy in the form of ATP
• Identify two examples of active transport.

  1) Sodium potassium pump pumping sodium ions and potassium ions against the gradient

  2) Amino acids moving in and out of the cell

  3) Glucose moving in or out of the cell against the concentration.
• What is active transport?


  The transport of materials across the membrane that requires energy input. The molecules go against the concentration gradient.
• How would a small non-polar molecule pass the plasma membrane (CO2/O2)?

  diffusion
• How do SMALL quantities of H2O pass the plasma membrane?

  diffusion - osmosis
• Why would large polar molecules travel through facilitated diffusion?

  They can't freely pass through the membrane. They are hydrophilic.
• What type of molecules would you expect to pass via facilitated diffusion?

  large polar molecules
• What is the difference between diffusion and facilitated diffusion?

  facilitated diffusion requires the use of a protein
• Identify two examples of passive transport.

  1) Simple diffusion: where the molecules move from high concentration to low concentration over time.

  2) Facilitated diffusion: where protein channels help move the ions for examples from high to low concentration. Osmosis is the diffusion of water

  
• What is a concentration gradient?


  It is the area where there is a difference of concentration of a substance between one area and the other
• What composes the cell wall of a prokaryote

  They are made primarily of peptidoglycan.
• What composes the cell wall of fungi?

  They are made primarily of chitin.
• What composes the cell wall of a plant?

  They are made primarily of cellulose.
• How do materials pass through the cell wall?


  There are small holes in the cell wall between plant cells called plasmodesmata that allow material in and out.
• What is the role of the cell wall?

  Gives the cell structure and support
• How does the cell wall protect the cell from hypotonic solutions?

  It takes up all the water by osmosis and starts to swell but then the cell wall stops it from exploding. This is called turgor pressure.

  
• How does the cell wall maintain cell structure?


  It is more rigid than just a cell membrane.
• What types of cells have a cell wall?

  Plants and fungi, and bacteria.
• How does H20 pass the plasma membrane quickly?

  protein
• Which type of protein can span the entire plasma membrane?

  Integral proteins- hydrophobic membrane; spanning regions interact with the hydrophobic region of the phospholipid bilayer
• Why are the fatty acids found on the inside of the plasma membrane?

  They are hydrophobic - water fearing
• Where are plasma membranes found in a cell?

  They are found on the edge surrounding the cell. And if it is in a plant it is inside the cell wall.
• Why does this type of material require bulk transport?

  They are too big to fit through channels and require a bunch of energy.
• Give two examples of materials that require a vesicle for export or a food vacuole for import.

  Large proteins or enzymes and starch for example.
• What types of materials require a vesicle for export or a food vacuole for import?

  Molecules like proteins and polysaccharides need to be transported through vesicles.
• True or False? Any molecule can use any transport protein.

  False some transport proteins are ion or molecule specific. Some molecules are too big to fit through certain proteins.
• Why does this type of material require a protein to pass through the membrane?

  Because the hydrophobic core would block their entryway through.
• Name two examples of materials that require a protein to pass through the membrane.

  1) Salt ions, K+ ions, water (travel through aquaporins) water can go through in class amounts without channels but not as much as needed.

  2) Glucose
• What types of materials require a protein to pass through the membrane?

  Polar and charged molecules, and large compounds
• Why does this type of material easily pass through the membrane?

  Since they are small they can pass through the pores of the membrane easily.
• Identify two examples of materials that can easily pass through the membrane.

  1) oxygen gas

  2) carbon dioxide gas
• What types of materials can easily pass through the membrane?

  Small nonpolar, uncharged molecules pass easily through the membrane.
• What is the function of glycolipids in the plasma membrane?

  The lipids help to increase cell stability and are involved in cell interactions.
• What is the function of glycoproteins in the plasma membrane?

  Glycoproteins have carbohydrate chains on them and they help with cell signaling and stability of the cell structure.
• What is the function of steroids in the plasma membrane?

  They alter the fluidity in the membrane and help with signaling in the cell and between cells.
• Define the fluid mosaic model.

  This model is a way of explaining how the components of a membrane like the proteins and glycolipids and cholesterol move in the fluid like environments.

  
• How does the membrane protein maintain the internal environment of a cell?

  It helps keep materials out of the cell that shouldn't be there and if there is a balance of say salt ions it will open protein channels to allow salt through to make it balanced. It does this for other molecules such as water, sugars, enzymes etcetera.
• How does the polarity of the membrane protein affect its orientation in the membrane?

  Hydrophobic parts of the secondary and tertiary structure of the protein will be found on the inside of the membrane to interact with hydrophobic portions of the cell membrane while the hydrophilic R groups will point to the outside and interact with the cell surrounding and inside the cell. The N-terminus end of the polypeptide chains that make up protein will be pointing to the extracellular side of the membrane while the c terminus end will pointing in toward the cytoplasm of the cell.