Transport
- Created by: lucyholly16
- Created on: 01-02-15 19:59
View mindmap
- Transport
- Facilitated Diffusion
- Doesn't require energy
- Uses transport proteins to move from high to low concentration
- Examples - Glucose or amino acids moving from blood into a cell
- Some carrier proteins do not extend through the membrane
- They bod and drag molecules through the lipid bilayer and release them on the opposite side
- Other carrier proteins change shape to move materials across the cell membrane
- Active Transport
- Requires energy of ATP
- Moves materials from low to high concentration
- Against concentration gradient
- Examples - Pumping Na+ out and K+ in against strong concentration gradient
- Called Na+-K+ pump
- 3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential
- Large molecules move into the cell by one of those two forms of endocytosis
- Pinocytosis - most common form of endocytosis. Takes in dissolved molecules as a vesicle
- Exocytosis - molecules are moved out of the cell by vesicles that fuse with the plasma mebrane
- This is how many hormones are secreted out and has nerve cells communicate with one another
- The opposite of endocytosis is exocytosis
- Exocytosis - molecules are moved out of the cell by vesicles that fuse with the plasma mebrane
- Small molecules and larger hydrophobic lipid soluble molecules move through easily e.g. O2, H2O, CO2
- Cholesterol = Stablity
- Less fluid at high temperatures
- More fluid at low temperatures
- Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own
- Proteins are critical to membrane function:
- Structural support - cholesterol
- Recognition - glycolipid
- Communication - glycoprotein
- Transport - channel protein
- Channel proteins are embedded in the cell membrane have a pore for materials to cross
- Carrier proteins can change shape to move material from one side of the membrane to the other
- Facilitated Diffusion
Comments
No comments have yet been made