Bio 204 CH4 Quiz
2) What is a liposome? How is a liposome made?
A liposome is an amphipathic molecule in the shape of a sphere with water trapped inside it. When an amphipathic molecule is added to turbulent water, it will spontaneously form itself into a liposome.
1) What are the characteristics of an amphipathic molecule? Name one.
An amphipathic molecule is a molecule that has a polar region that is hydrophilic and a nonpolar region that is hydrophobic. Triglyceride is an example of an amphipathic molecule. The three fatty acids make up the nonpolar, hydrophilic end and a glycerol molecule makes up the polar, hydrophobic end. Phosopholipids are another example of amphipathic molecules. The phosphate head makes up the polar, hydrophilic region and the two fatty acids make up the nonpolar, hydrophobic tails.
4) Name and describe the problem that the evolution of a membrane solved.
Due to diffusion, the RNA molecules and bases in the primordial soup had a net movement towards lower concentration, thereby causing them to be too spaced apart to replicate. By encasing RNA molecules in a liposome, RNA could replicate much faster.
5) Describe what is meant by the "osmosis crisis?" What, exactly, caused it?
Osmosis crisis refers to the problem that water will flow into a cell due to osmosis, causing it to swell and eventually lyse. This is because water will move to where there is a lower water concentration. Since there are a ton of replicating RNA molecules and other solutes in the cell, water will tend to flow into a cell.
6) What intracellular structure evolved to solve the osmosis crisis? How did it do that and what important energy molecule is also required for that solution?
The evolution of the proton pump solved the osmotic crisis of a cell. The proton pump evolved from a specific RNA molecule whose catalytic function was to pump protons. The energy for pumping protons out of the cell is supplied by ATP.
3) b) shrink a red blood cell
When the fluid outside the red blood cell is hyperosmotic, there are more solutes outside the cell than inside the cell, causing water to leave the cell towards the solutes outside the cell and shrink.
3) a) lyse a red blood cell
When the fluid outside the red blood cell is hypoosmotic, there are more solutes inside the cell, water will flow towards the solutes in the cell, causing the cell to swell and eventually burst (lyse).
3) c) make a red blood cell happy (neither shrink nor swell/lyse).
When the fluid outside the red blood cell is isosmotic to the fluid inside the cell, there is the same concentration of solutes inside and outside of the cell, there is no net flow of water, so cell remains the same size.
