What do channel proteins do?
Key Terms
What do channel proteins do?
Form pores in membrane for charged particles to diffuse through (down their concentration gradient)
Related Flashcard Decks
| Term | Definition |
|---|---|
What do channel proteins do? | Form pores in membrane for charged particles to diffuse through (down their concentration gradient) |
What is facilitated diffusion? | When large/charged particles diffuse through carrier proteins or channel proteins down a concentration gradient |
Name 3 factors that affect the rate of simple diffusion | Concentration gradient (Higher it is = faster rate of diffusion) Thickness of exchange surface Surface area |
What are microvilli? | Projections formed by cell-surface membrane folding up on itself |
How do microvilli increase the rate of diffusion? | Give cell a larger surface area ∴ more particles can be exchanged in same amount of time = increasing rate of diffusion |
Name 2 factors that affect the rate of facilitated diffusion | Concentration gradient Number of channel/carrier proteins |
Describe how the number of channel/carrier proteins affects the rate of facilitated diffusion | Once all proteins in membrane are in use = facilitated diffusion can't happen any faster (even if concentration gradient is increased) Greater no. of carrier/channel proteins = faster rate of facilitated diffusion |
Why can water diffuse directly through the membrane even though it's polar? | ∵ it's relatively small |
Define osmosis | Diffusion of water molecules across a partially permeable membrane from an area of higher water potential to an area of lower water potential |
What is water potential? | Tendency of water molecules to diffuse out of or into a solution |
What has the highest water potential? | Pure water |
All solutions have ____ water potential than pure water | lower |
If 2 solutions have same water potential, they are said to be ____ | isotonic |
Name 3 factors that affect the rate of osmosis | Water potential gradient (Higher water potential gradient = faster rate of osmosis) Thickness of exchange surface Surface area of exchange surface |
Red Blood Cell Fill in the blanks | |
Plant Cell Fill in the blanks | Label Function Cell Wall Rigid outer layer that provides structure and protection to the plant cell. Cell Membrane Semi-permeable layer that controls what enters and exits the cell. Cytoplasm Jelly-like substance where cell activities occur; holds organelles in place. Nucleus Control center of the cell; contains DNA and regulates cell functions. Vacuole Large central sac that stores water, nutrients, and waste; helps maintain shape. Chloroplast Site of photosynthesis; converts sunlight into energy using chlorophyll. Mitochondria Powerhouse of the cell; produces energy through cellular respiration. |
Describe what happens when a plant cell is placed in a very concentrated solution (i.e. how it becomes plasmolysed) | Water moves out of cell by osmosis Cell has greater water potential Water moves down water potential gradient |
Make a 15 cm3 solution of 0.4 M sucrose solution using 1 M sucrose solution | |
What technique do you use to make several solutions of different, known concentrations? | Serial dilution technique |
Investigating water potential using serial dilutions Describe how you would make 5 serial dilutions of sucrose solutions, starting with initial sucrose solutions of 2 M | Dilute each solution by factor of e.g. 2 Line up 5 test tubes in rack Add 10 cm3 of initial 2 M sucrose solution to test 1st test tube & 5 cm3 of distilled water to other 4 test tubes Using pipette, draw 5 cm3 of solution from 1st test tube & add it to distilled water in 2nd test tube Mix solution thoroughly Now have 10 cm3 of solution that's half concentrated as solution in 1st test tube (it's 1 M) Repeat process 3 more times to create solutions of 0.5 M, 0.25 M and 0.125 M |