bio 204 week 4
What is a liposome? How is a liposome made?
A liposome is a constraining agent. It is surrounded by a lipid bilayer with two lines of the amphipathic molecule. They are made in the laboratory by vigorously mixing a solution of amphipathic molecules in water. They can also be found in nature where any sort of energetic disturbance of a pool of water with amphipathic molecules can make liposomes.
What are the characteristics of an amphipathic molecule? Name one.
An amphipathic molecule has a polar region and a nonpolar region.
Name and describe the problem that the evolution of a membrane solved.
The evolution of a membrane solved the osmosis crisis. Membranes are selectively permeable, so they can replicate outside the cell.
What, specifically, is the "osmosis crisis?" What, exactly, caused it?
The osmosis crisis refers to the crisis involving the large RNA molecules which were trapped inside the fatty acid liposomes, meaning that they could not diffuse toward lower concentrations outside at all. RNA strands in the cell replicate, causing their concentration to increase and newly replicated polymers remain trapped inside the cells.
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 proton pump evolved to solve the osmosis crisis. The pump actively pumps hydrogen ions out of the cell, which reduces the concentration of protons inside. This equalizes the total number of solutes. Nucleoside triphosphate is the energy source for this.
Describe the circumstances (use the words, solute, inside, outside, hyperosmotic, hypoosmotic, flow of water) that would lyse a red blood cell, shrink a red blood cell, make a red blood cell happy (neither shrink nor swell/lyse),
When the outside solution is hypo-osmotic, water flows into the cell, causing it to swell and lyse. When the outside solution is hyperosmotic, water flows out of the cell, causing the cell to shrink. A iso-osmotic cell has an equal amount of solute and solution inside and outside, so there is no net flow of water. The cell remains the same size, so the cell is happy.
