In a generalized-transduction experiment, phages arecollected from an E. coli donor strain of genotype cys+leu+ thr+ and used to transduce a recipient of genotypecys- leu- thr-. Initially, the treated recipient populationis plated on a minimal medium supplemented with leucine and threonine. Many colonies are obtained.a. What are the possible genotypes of these colonies?b. These colonies are then replica plated onto threedifferent media: (1) minimal plus threonine only, (2)minimal plus leucine only, and (3) minimal. Whatgenotypes could, in theory, grow on these three media?c. Of the original colonies, 56 percent are observed togrow on medium 1, 5 percent on medium 2, and nocolonies on medium 3. What are the actual genotypes ofthe colonies on media 1, 2, and 3?d. Draw a map showing the order of the three genes andwhich of the two outer genes is closer to the middle gene
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.
In a generalized-transduction experiment, phages are
collected from an E. coli donor strain of genotype cys
+
leu
+ thr
+ and used to transduce a recipient of genotype
cys- leu- thr
-. Initially, the treated recipient population
is plated on a minimal medium supplemented with leucine and threonine. Many colonies are obtained.
a. What are the possible genotypes of these colonies?
b. These colonies are then replica plated onto three
different media: (1) minimal plus threonine only, (2)
minimal plus leucine only, and (3) minimal. What
genotypes could, in theory, grow on these three media?
c. Of the original colonies, 56 percent are observed to
grow on medium 1, 5 percent on medium 2, and no
colonies on medium 3. What are the actual genotypes of
the colonies on media 1, 2, and 3?
d. Draw a map showing the order of the three genes and
which of the two outer genes is closer to the middle gene
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