Briefly describe the experiment carried out to demonstrate that proteins are capable of lateral movement in cell membranes.

In the early days of ribosome research, before the exact role of ribosomes was clear, a researcher made the following observation. She could find, in sedimentation experiments on bacterial lysates, not only 3OS, 50S, and 70S particles, but also some particles that sedimented at about 100S and 130S. When she treated such a mixture with EDTA, everything dissociated to 30S and 50S particles. Upon adding divalent ions, she could regain 70S particles, but never 100S or 130S particles. (a) Suggest what the 10oS and 130S particles might represent, in light of cur- rent knowledge of protein synthesis. What important discovery did the researcher miss? (b) Why do you think reassociation to 100S and 130S particles did not work?

Explain (using the correct terminology and drawing an image) what happens to the cells in the following environments: A human blood cell (0.9% salt) is placed in a saltwater tank (27.5% salt). - A bacterial cell with 35% organic material in their cytoplasm is living in a tank filled with 35% sulfur. - A freshwater plant cell (75% water) is living in a pond that floods over.

If you did a classic Pulse-Chase experiment to follow the path of a secreted protein, and you forgot to do the Chase, which of the following would you observe?     No radioactivity would be seen in any of the structures.     Radioactivity would increase first in rough ER, then Golgi Complex, then secretory vesicles, but it would remain high in all, never decreasing.     Nothing would change     Radioactivity would increase in all 3 structures simultaneously and stay high.