Drug resistance by HGT is happening between an E. coli strain and a pathogenic bacterium Klebsiella pneumoniae, which is causing post-operative infections. This transfer requires that living cells are in contact with one another. The most likely form of HGT is...

Question

Drug resistance by HGT is happening between an E. coli strain and a pathogenic bacterium Klebsiella pneumoniae, which is causing post-operative infections. This transfer requires that living cells are in contact with one another. The most likely form of HGT is...

BlackTom AI · Accepted Answer

Because the transfer requires living cells to be in direct contact, the mechanism is conjugation: plasmid-mediated DNA transfer through a mating pair (sex pilus) between bacteria.

1. Relevant knowledge points and concepts
- Horizontal gene transfer (HGT) in bacteria occurs primarily by three mechanisms: conjugation (cell-to-cell contact and plasmid transfer), transformation (uptake of free DNA from the environment), and transduction (phage-mediated DNA transfer).
- Conjugation commonly transfers plasmids carrying antibiotic-resistance genes (R plasmids), often between different species (e.g., E. coli to Klebsiella pneumoniae). This requires viable donor and recipient cells.
- Transformation requires extracellular DNA from lysed cells; transduction requires bacteriophages to package and deliver DNA.

2. Step-by-step reasoning process
- The stem explicitly states the transfer “requires that living cells are in contact with one another.” That condition matches conjugation, not transformation or transduction.
- Conjugation mechanism: donor cell with conjugative plasmid produces a pilus, forms a mating bridge, and transfers single-stranded plasmid DNA to the recipient. After transfer, both cells replicate complementary strands to reconstitute double-stranded plasmids.

3. Intermediate mechanistic steps (molecular detail)
- Donor (F+ or plasmid-bearing) synthesizes sex pilus and attaches to recipient (F−).
- Rolling-circle replication initiates at the plasmid origin of transfer (oriT).
- A single strand is nicked and transferred through the pilus into the recipient.
- Both cells synthesize the complementary strand; the recipient acquires resistance genes encoded on the plasmid.
- Mobile elements (transposons, integrons) on plasmids can mobilize diverse resistance determinants between species.

4. Why the correct answer is correct
- Only conjugation requires direct live cell-to-cell contact and efficiently moves plasmids carrying resistance determinants across species barriers such as E. coli → Klebsiella.

5. Why the other options are incorrect
- Transformation: requires extracellular DNA from lysed cells, not necessarily live-cell contact.
- Transduction: depends on bacteriophages to transfer DNA, not direct bacterial contact.

6. Conclusion
- Conjugation is the most likely form of HGT here; this matches the provided answer, Conjugation.

Drug resistance by HGT is happening between an E. coli strain and a pathogenic bacterium Klebsiella pneumoniae, which is causing post-operative infections. This transfer requires that living cells are in contact with one another. The most likely form of HGT is...单项选择题

类似问题

leu- bacteria are mixed in a flask with leu+ bacteria, and soon all bacteria are leu+. However, if the leu– cells are on one side of a U-tube and the leu+ cells are on the other, the leu– cells do not become prototrophic. This suggests which mechanism of gene transfer?

After performing a mating experiment, the agar plate has numerous transconjugants growing on it. What conclusion can be drawn from this observation?

Conjugation involves:

What is the function of the F-pilus?

Which of the following statements about Hfr cells and bacterial conjugation is false?

Which of the following statements is correct?

Which of the following statements correctly describes F- cells and F+ cells?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单