586 Discussion Questions — Part F 



DISCUSSION QUESTIONS— PART F 



1. An alternative to rapid flow systems for observing spectrophotometric 

 changes during reaction is to introduce a sudden pulse of heat, thereby raising 

 the temperature, and to measure the spectrophotometric changes as the 

 reaction mixture approaches a new equilibrium. This method is sometimes 

 called a relaxation method. ' Describe suitable apparatus for such measurements 

 on myoglobin. 



2. The technique of neutron activation is used to locate spots on a chromat- 

 ogram containing phosphorus. For this purpose, the chromatogram is 

 placed in the neutron flux of a reactor. Afterward, the chromatogram is 

 autoradiographed. Discuss the details, advantages, and disadvantages of 

 this technique. 



3. One of the advantages of phase microscopy is that one can measure 

 quantitatively the thickness of parts of cells. Develop the necessary symbolic 

 expressions to describe quantitatively how this is done. 



4. The ultraviolet microscope can be made more useful by translating a 

 given ultraviolet wavelength to a visible one on a television tube screen. 

 RCA has developed a three-color scheme using three ultraviolet wavelengths. 

 Describe the equipment briefly. What are its advantages? Its dis- 

 advantages ? 



5. Certain absorption bands of cytochromes can be intensified by reducing 

 the temperature to that of liquid nitrogen. Describe briefly the necessary 

 equipment and the type of results obtained. In so far as possible, explain 

 these on a theoretical basis. 



6. Electrophoresis refers to the motion of charged ions in an electrical 

 field. It is used to separate different types of molecules, including very 

 similar proteins. Develop the theory of electrophoretic separation. 



7. Two frequently used types of electrophoresis are paper and Tiselius. 

 Describe the necessary equipment for each and the advantages and dis- 

 advantages of each. 



8. Some laboratories labeled "biophysics" owe their existence and unique 

 character to measurements made with the analytical ultracentrifuge. Des- 

 cribe this apparatus and outline the theory necessary to interpret ultra- 

 centrifuge data. Cite specific examples of its use. 



9. Some persons labeled " biophysicists " have worked with equipment 

 measuring oxygen concentrations in terms of the current through a platinum 

 electrode. Describe the necessary apparatus and indicate how it operates. 

 What is the advantage of having the electrode rotating or vibrating? Why 

 are the electrodes often covered with a plastic film? 



10. One technique mentioned in the text for the preparation of electron 

 microscope samples involved replacing the H 2 with CO s and then going 





