The following table contains statements pertaining to Hfr, F+, F', and/or F- strains of bacteria. Indicate in respective boxes if the statements apply to each category by putting Hfr, F+, F', F- beside the statement.
a) Contains genes that regulate conjugation and the transfer of DNA from one cell to another
b) Always acts as the recipient in conjugation
c) F factor is integrated into the host chromosome
d) Cannot form a pilus
e) F factor is in the plasmid form carrying a segment of chromosomal DNA
The categorization of the F+ / F- and Hfr bacteria follows some pretty basic rules. Bacteria exchange some of their genetic material "horizontally" - they can pass genetic material from one bacterium to another via a process called conjugation. Only some bacteria can actually initiate this transfer however, and others tend to receive. The F-factor, or fertility factor, is a segment of genes which cumulatively give the bacterium the ability to initiate conjugation. This ...
The expert examines the contained genes of regulated conjugations.
Recombination in bacteria and in viruses that infect bacteria.
Four E. coli strains of genotype a+ b- are labeled 1,2,3 and 4. Four strains of genotype a- b+ are labeled 5,6,7, and 8. The two genotypes are mixed in all possible combinations and (after incubation) plated to determine the frequency of a+ b+ recombinants. The following results were obtained, where M = many recombinants, L = low numbers of recombinants, and O = no recombinants.
On the basis of these results, assign a sex type (either Hfr, F+, or F-) to each of the strains.View Full Posting Details