a. You have a test tube containing 5 ml of a solution ofbacteriophages, and you would like to estimate thenumber of bacteriophages in the tube. Assuming thetube actually contains a total of 15 billion bacteriophages, design a serial dilution experiment thatwould allow you to estimate this number. Ideally,the final plaque-containing plates you count shouldcontain more than 10 and fewer than 1000 plaques.b. When you count bacteriophages by the serialdilution method as in part (a), you are assuming aplating efficiency of 100%; that is, the number ofplaques on the petri plate represents exactly thenumber of bacteriophages you mixed with the plating bacteria. Is there any way to test the possibilitythat only a certain percentage of bacteriophageparticles can form plaques (so that the plating efficiency would be less than 100%)? Why is it fair toassume that any plaques are initiated by one ratherthan multiple bacteriophage particles?
Genetic Recombination
Recombination is crucial to this process because it allows genes to be reassorted into diverse combinations. Genetic recombination is the process of combining genetic components from two different origins into a single unit. In prokaryotes, genetic recombination takes place by the unilateral transfer of deoxyribonucleic acid. It includes transduction, transformation, and conjugation. The genetic exchange occurring between homologous deoxyribonucleic acid sequences (DNA) from two different sources is termed general recombination. For this to happen, an identical sequence of the two recombining molecules is required. The process of genetic exchange which occurs in eukaryotes during sexual reproduction such as meiosis is an example of this type of genetic recombination.
Microbial Genetics
Genes are the functional units of heredity. They transfer characteristic information from parents to the offspring.
a. You have a test tube containing 5 ml of a solution of
bacteriophages, and you would like to estimate the
number of bacteriophages in the tube. Assuming the
tube actually contains a total of 15 billion bacteriophages, design a serial dilution experiment that
would allow you to estimate this number. Ideally,
the final plaque-containing plates you count should
contain more than 10 and fewer than 1000 plaques.
b. When you count bacteriophages by the serial
dilution method as in part (a), you are assuming a
plating efficiency of 100%; that is, the number of
plaques on the petri plate represents exactly the
number of bacteriophages you mixed with the plating bacteria. Is there any way to test the possibility
that only a certain percentage of bacteriophage
particles can form plaques (so that the plating efficiency would be less than 100%)? Why is it fair to
assume that any plaques are initiated by one rather
than multiple bacteriophage particles?
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