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Bacterial conjugation, mediated mainly by conjugative plasmids such as F, represents a potential health threat through the sharing of genes for pathogenicity or antibiotic resistance. Given that more than 400 different species of bacteria coinhabit a healthy human gut and more than 200 coinhabit human skin, Francisco Dionisio [(2002) Genetics 162:1525–1532] investigated the ability of plasmids to undergo between-species conjugal transfer. The following data are presented for various species of the enterobacterial genus Escherichia. The data are presented as “log base 10” values; for example, –2.0 would be equivalent to 10–2 as a rate of transfer. Assume that all differences between values presented are statistically significant.
- (a) What general conclusion(s) can be drawn from these data?
- (b) In what species is within-species transfer most likely? In what species pair is between-species transfer most likely?
- (c) What is the significance of these findings in terms of human health?
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Concepts of Genetics (12th Edition)
- Assume that there are horizontal gene transfers between two completely different bacterial species. In one case it is a plasmid that is transmitted via conjugation, in the other case it is it is a part of the bacterial chromosome that is transferred via transformation. In which of the two cases is it likely that the transferred DNA will be present? left and can function in the recipient cells? Explain the biological background to your answerarrow_forwardWhat is horizontal gene transfer? What are the three mechanisms for this to occur in bacteria? What are the components needed for the processes of transformation, conjugation, and transduction? How does each process occur? What genes are involved in each process? How do generalized and specialized transduction differ? What is the end result of each? What is recombination? What is the importance to bacteria & archaea? What are the two types of recombination? What are the details of each type? What components are needed for each type?arrow_forwardIn a P1 transduction experiment, the P1 lysate contains phages thatcarry pieces of the host chromosomal DNA, but the lysate also containsbroken pieces of chromosomal DNA. If a P1 lysate is used to transfer chromosomal DNA to another bacterium, how could you show experimentally that the recombinant bacterium has been transduced (i.e., has taken up a P1 phage with a piece of chromosomal DNA inside) versus transformed (i.e., has taken up a piece of chromosomal DNA that is not within a P1 phage coat)?arrow_forward
- Briefly discuss the following questions in 3 to 5 sentences. What is horizontal gene transfer? What are the three mechanisms for this to occur in bacteria? What are the components needed for the processes of transformation, conjugation, and transduction? How does each process occur? What genes are involved in each process? How do generalized and specialized transduction differ? What is the end result of each? What is recombination? What is the importance to bacteria & archaea? What are the two types of recombination? What are the details of each type? What components are needed for each type?arrow_forwardDescribe the 3 ways in which bacteria can transfer genetic material to each other via horizontal gene transfer. Be sure to explain the following: How is DNA transferred between bacteria, is there direct contact between bacteria and whether a plasmid is involved or not.arrow_forwardNine rII− mutants of bacteriophage T4 were used inpairwise infections of E. coli K(λ) hosts. Six of themutations in these phages are point mutations; theother three are deletions. The ability of the doubly infected cells to produce progeny phages in large numbers is scored in the following chart.1 2 3 4 5 6 7 8 91 − − + + − − − + +2 − + + − − − + +3 − − + − + − −4 − + − + − −5 − − − + +6 − − − −7 − + +8 − −9 −The same nine mutants were then used in pairwise infections of E. coli B hosts. The production of progenyphages that can subsequently lyse E. coli K(λ) hosts isnow scored. In the table, 0 means the progeny do notproduce any plaques on E. coli K(λ) cells; − meansthat only a very few progeny phages produce plaques;and + means that many progeny produce plaques(more than 10 times as many as in the − cases).1 2 3 4 5 6 7 8 91 − + + + + − − + +2 − + + + + − + +3 0 − + 0 + + −4 − + − + + +5 − + − + +6 0 0 − +7 0 + +8 − +9 −a. Which of the mutants are the three deletions? Whatcriteria did…arrow_forward
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