4 parts of the plasma membrane
- phospholipids
- proteins
- carbohydrates
- cholesterol
Define fluid
Movement - components are floating around, not static
Define mosaic
Many small pieces come together to make a larger component
Function of the plasma membrane
Separates the inside from the outside of the cell
Structure of phospholipids
- Hydrophilic head
- a phosphate group (polar)
- a glycerol molecule - Hydrophobic tails
- 2 fatty acid chains (nonpolar)
How does the phospholipid layer select what passes through it?
Selects by size and charge
- small, nonpolar particles
What effects membrane fluidity?
- temperature
- higher temp, increased fluidity
- lower temp, decreased fluidity, more rigid - phospholipid type
- unsaturated fatty acid tails, more fluid
- saturated fatty acid tails, less fluid, more rigid
- Unsaturated phospholipids will stay fluid at lower temperatures
Function of proteins in the membrane
Cross membrane transport and cell communication
Two types of proteins in membrane
- integral proteins
- peripheral proteins
What are integral proteins?
Proteins integrated completely into/through the bilayer
Allow for cross membrane transport
a) Facilitated diffusion (passive, no energy required)
i) Protein transport through tubes/tunnels call protein channels
b) Active transport (requires energy (ATP) to proceed)
i) Pump ions out to create electrical impulses, creates ATP
- Pump can be used to pump Na out, K out
What is facilitated diffusion?
Protein transport through tubes/tunnels call protein channels; passive, no energy required
What is active transport?
Pump ions out to create electrical impulses, creates ATP; requires energy
What are peripheral proteins?
Occur only on the exterior of the membrane (on the edges)
1) Act as enzymes, helps hold cell shape, attached to carbohydrates
a) Ones on the outer edge have carbohydrates attached to them
b) Inner ones act as enzymes, help hold cell shape
What is the function of carbohydrates in the membrane?
Adhesion, cell recognition and cell signaling
1. Helps communication, regulate themselves, and maintain and develop tissues
2. Allows immune cells to differentiate between body cells and foreign cells (destroy)
c. Sometimes the sugars make the cell sticky and it sticks to another cell - adhesion d. Can also detect particles, if it's food it'll bring it into the cell
*they are only present on the outer surface of the membrane
What is a glycoprotein?
Polysaccharide attached to a peripheral protein
What is a glycolipid?
Polysaccharide attached to a phospholipid
What is the function of cholesterol in the membrane?
Helps minimize effect of temperature on fluidity
- Low temps: increases fluidity, keeps phospholipids from packing too tightly by disrupting packing
- High temps: reduces fluidity, holds phospholipid together, reduces movement
What is a solution?
When something is dissolved in something else
What is a solute?
The dissolved particles in a solution
What is a solvent?
The dissolving medium in a solution
What does like dissolves like mean?
Polar solvents dissolve polar solutes, non-polar solvents dissolve non-polar solutes
What is tonicity?
Relative solute concentration
What does hypertonic mean?
The solution with the higher solute concentration
What does hypotonic mean?
The solution with the lower solute concentration
