Thinking and Reading Questions for Chapter 5
1. The first experimental evidence for the membrane structure model – the
“phospholipids double layered, fluid mosaic, and semi permeable” model,
involved chemical analysis of the cell membrane components. What were the
major components they found that suggested the chemical make up of the
membrane?
2. The composition analysis was followed by the Overton experiment that analyzed
the solubility and the size of the molecules that cell surface made up with.
According to his finding, which substance is easier to penetrate through
membrane: Hydrophilic and polar molecules or hydrophobic and non-polar
molecules?
What was the other factor that determines the rate of diffusion?
3. In 1925, E. Gorter and F. Grendel used red blood cells that are “unnucleus” and
can be made into “ghost cells” to test lipid contents against total surface area of
the lipid layer of a cell. By their calculation, how many times were there enough
lipid molecules with which to cover cell surface?
4. In 1930, James Danielli and Hugh Davson measured the surface tension of oil
droplets and that of the cells. The finding agrees with the Gorter and Grendel
experiments. What was their finding?
5. In 1959, what instrument that was not available previously did J. David Robertson
use to make the finding that agreed with the bi-layer model? How did he explain
the way proteins must exists in the bi-layer?
6. In 1966, J. Lenard and S. J. Singer observed that light properties (reflection,
penetration etc) data did not agree with the single layered protein model. If the
natural state of protein is a folded up one such as helix, would spreading out of
the protein needs energy be thermodynamically favorable?
7. In 1972, Singer and Garth Nicholson proposed the Singer – Nicholson model.
What was this model like?
8. What is the name of the EM technique that enables us to “see” the surface of the
cell membrane?
9. In Sidney and Sighild Tamm experiment using protozoans living in the guts of the
termites, it was observed that part of the membrane was able to rotate rapidly.
What membrane property did it suggest?
10. What did the results of the David Frye and Michael Edidin’s mouse – human
“super cell” experiment suggest?
11. Is the “capping” phenomenon an active process? How to prove that it is an energy
consuming process?
12. Are the proteins in the membrane distributed evenly or unevenly according to L.L.
Van Deenen’s digestion experiments?
12. Fashion of Exchange
Diffusion
Active
Transport
Pinocytosis
Phagocytosis Recepter
Mediated
Endocytosis
Does it have
to be from
high
concentration
to low
concentration?
Need energy?
What material
does this
process
transport?
Does it
involve
membrane
movement?
13. Refer to page 98 (Extracellular Matrix) and page 89 (How cells talk to one another),
summarize briefly how important it is for cell surface molecules to mediate cell
communication. (One paragraph)