Study Guide: Membranes
To-Do Date: Jan 30 at 12:00pmCartoon
In the comic, a phospholipid points a water gun at the other phospholipids in a cell membrane. The fatty acid tails of those phospholipids bend away from the water gun. The phospholipid says "Hey guys! Look I have a water gun!" The comic is titled "membrane pranks."
What are the two parts of a phospholipid? Which part would not mix well with water? If that part did mix well with water, how would the drawing in the comic change?
Learning Objectives
By the end of this week you should be able to
- Draw and label the parts of a cell membrane: phospholipids, fatty acid tails, phosphate heads, transport proteins, cytoskeleton
- Explain how the phospholipid bilayer (structure) determines which molecules can cross directly through the membrane and which need to be transported across via proteins or endo/exocytosis (function).
- Define diffusion, osmosis, facilitated diffusion, active transport, endocytosis and exocytosis.
- Identify and describe the method of transport for each of the following categories of molecules: water, carbon dioxide, oxygen, small nonpolar molecules, subunits, ions, macromolecules.
- Explain cell signaling- What are cell signals, how are they received by cells.
- Explain signal transduction
- Give examples of cellular and nuclear responses
- Apply this information to the insulin signaling pathway.
Study guide questions
1. Draw and label parts of cell membrane:(see list above in Learning Objectives). Identify which parts are polar and which are nonpolar.
2. Fill in this chart
| Type of molecule | Method of crossing the membrane | What about the membrane structure allows them to cross in this manner? |
| small non-polar molecules (O2, CO2, H2O) | ||
| medium sized non-polar molecules (fatty acids) | ||
| medium sized polar molecules ( sugar, amino acids, ions like Calcium) | ||
| very large molecules (proteins, carbohydrates) |
3. How would a cell secrete a protein that it had made? (ie how does the protein get from inside the cell to outside the cell). An example would be the cells that line your small intestine secrete digestive enzymes. Make sure to use the following vocabulary: endocytosis, vesicles, cytoskeleton, fusion of vesicle with the membrane.
4. How would a cell secrete H+? (ie how do these ions get from inside the cell to outside the cell) An example of this is what happens in your stomach-cells secrete H+ to keep the stomach acidic. Make sure to use the following vocabulary: high concentration, low concentration, concentration gradient, facilitated diffusion, transport proteins,
5. Cells receive signals that tell them what to do. Explain how signal transduction works so that small amounts of a signal can cause a large response in a targeted cell.