Satellite DNAs are highly repeated sequences of unknown function. The satellite DNA from the meal worm beetle is remarkable since it represents over 50% of this insects genome. In this exercise, students first isolate DNA from beetle larvae by a simple and safe procedure. They then digest the DNA with EcoR1 and examine the satellite DNA following electrophoresis as shown on the gel pictured below. Suffient materials are provided so that the experiment can be carried out twice by eight groups of students.
Each protein carries in its amino acid sequence information pertaining to its evolutionary history and origin, and provides clues to the evolutionary history of the organism in which it is found. Indeed, proteins existing today are in effect living fossils. This concept is illustrated in this exercise where eight groups of students examine the abilities of antibodies against cow gamma globulin to react with gamma globulins in the sera of cow, goat, sheep, horse, and chicken.
Microtubules are hollow cylinders made up of polymers of the protein tubulin. Microtubules are major components of cilia and flagella, which are tail like projections that are covered by a plasma membrane and extend outwards from the cell. Motile cilia are used for locomotion and food gathering by some protozoa and are found in the lining of the trachea, where their wave like motion propels mucus, dust and other foreign matter out of the lungs.