Question

which of the following statements is true about transfer of the f factor?

check all that apply

cells that contain an f factor produce a sex pilus.

cells that obtain an entire f factor become f+.

integration of the f factor into the chromosome makes cells f-.

hfr cells are unable to make a sex pilus.

transfer of an entire f factor takes about 100 minutes.

Explanation:

Analyze the biological characteristics of the F factor and conjugation

• Cells containing the F factor (\(\text{F}^+\) or \(\text{Hfr}\) cells) express genes to synthesize a sex pilus.
• Recipient cells (\(\text{F}^-\)) that receive a complete copy of the F plasmid during \(\text{F}^+ \times \text{F}^-\) conjugation are converted into \(\text{F}^+\) donor cells.
• Integration of the F plasmid into the bacterial chromosome results in an \(\text{Hfr}\) (high frequency of recombination) cell, not an \(\text{F}^-\) cell.
• \(\text{Hfr}\) cells retain the F factor genes and are fully capable of producing a sex pilus.
• Transfer of the entire chromosome from an \(\text{Hfr}\) cell takes approximately 100 minutes in E. coli, but transfer of the small, independent F plasmid itself during standard \(\text{F}^+ \times \text{F}^-\) conjugation takes only a few minutes.

Evaluate each statement

• Statement 1: "Cells that contain an F factor produce a sex pilus." -> True (Both \(\text{F}^+\) and \(\text{Hfr}\) cells produce a sex pilus).
• Statement 2: "Cells that obtain an entire F factor become F+." -> True (Receiving the complete F plasmid converts a recipient to \(\text{F}^+\)).
• Statement 3: "Integration of the F factor into the chromosome makes cells F-." -> False (It makes them \(\text{Hfr}\)).
• Statement 4: "Hfr cells are unable to make a sex pilus." -> False (They can and do make a sex pilus).
• Statement 5: "Transfer of an entire F factor takes about 100 minutes." -> False (Transfer of the F plasmid takes only a few minutes; 100 minutes is the time required to transfer the entire E. coli chromosome during \(\text{Hfr}\) conjugation).

Answer:

• Cells that contain an F factor produce a sex pilus. (Correct answer)
• Cells that obtain an entire F factor become F+. (Correct answer)
• Integration of the F factor into the chromosome makes cells F.
• Hfr cells are unable to make a sex pilus.
• Transfer of an entire F factor takes about 100 minutes.