BIOS 260 Final Exam with Verified Solutions
What is transformation? Correct Ans-a form of horizontal gene transfer; the bacterial DNA
is transferred as "naked" DNA when a recipient cell takes up this naked DNA from the
environment.
SInce DNA is naked, transformation is the only horizontal gene transfer process that is
sensitive to DNase.
What is transduction? Correct Ans-a form of horizontal gene transfer; the transfer of
bacterial DNA inside of a phage coat. The transducing particle is formed when a fragment of
Bacterial DNA mistakenly enters the protein coat. This tranducing particle (NOTE: not a
bacteriaphage because the DNA inside belongs to a bacteria and not a bacteriaphage) then
will invade a different cell after the protein coat attaches to the new cell, where it may
become integrated into the recipient genome via homologous recombination.
What is conjugation? Correct Ans-a form of horizontal gene transfer; the donor cell must
physically contact the recipient cell.
What does transformation, transduction, and conjugation have in common? Correct Ans-
All processes of horizontal gene transfer, where a fragment of ssDNA is moved from a donor
, BIOS 260 Final Exam with Verified Solutions
cell to a recipient cell. It is always DNA being transferred. Recipient cells are called
recombinants after this transfer.
What are the differences between transformation, transduction, and conjugation? Correct
Ans-Transformation transfers 'naked' DNA that is uptaken from the environment surrounding
the recipient cell. This is the only process that is sensitive to DNase.
Transduction transfers DNA that is enveloped by a phage protein coat. This DNA is a fragment
of the donor chromosome.
Conjugation is the only transfer that requires Cell-to-Cell contact between donor and
recipient. Conjugation uses a specialized structure called a pilus (present only on the donor
cell) to transfer the DNA from cell-to-cell.
Describe conjugation between an F+ and F- cell Correct Ans-1) Cells make contact: F pilus
of F+ cell contacts recipient F- cell.
2) Initiation of transfer: One strand of F plasmid is cut at the origin of transfer, meanwhile the
pilus retracts to bring the recipient cell closer.
, BIOS 260 Final Exam with Verified Solutions
3)Transfer: single strand of F plasmid moves into recipient cell. The complement is made as it
enters the recipient cell.
4)Transfer is complete: both cells are F+
Which cell types can participate in conjugation? Correct Ans-both gram + and gram -. Both
donor and recipient cells:
F+ --> F- resulting in F+
HFR--> F- resulting in F'
Define Hfr cell Correct Ans-
Define F+ cell Correct Ans-cell that contains the F plasmid, capable of producing the sex
pilus.
Define F- cell Correct Ans-a cell lacking F plasmid, is unable to form sex pilus.
Define F' cell Correct Ans-HFR cell makes contact with F- cell.
What is transformation? Correct Ans-a form of horizontal gene transfer; the bacterial DNA
is transferred as "naked" DNA when a recipient cell takes up this naked DNA from the
environment.
SInce DNA is naked, transformation is the only horizontal gene transfer process that is
sensitive to DNase.
What is transduction? Correct Ans-a form of horizontal gene transfer; the transfer of
bacterial DNA inside of a phage coat. The transducing particle is formed when a fragment of
Bacterial DNA mistakenly enters the protein coat. This tranducing particle (NOTE: not a
bacteriaphage because the DNA inside belongs to a bacteria and not a bacteriaphage) then
will invade a different cell after the protein coat attaches to the new cell, where it may
become integrated into the recipient genome via homologous recombination.
What is conjugation? Correct Ans-a form of horizontal gene transfer; the donor cell must
physically contact the recipient cell.
What does transformation, transduction, and conjugation have in common? Correct Ans-
All processes of horizontal gene transfer, where a fragment of ssDNA is moved from a donor
, BIOS 260 Final Exam with Verified Solutions
cell to a recipient cell. It is always DNA being transferred. Recipient cells are called
recombinants after this transfer.
What are the differences between transformation, transduction, and conjugation? Correct
Ans-Transformation transfers 'naked' DNA that is uptaken from the environment surrounding
the recipient cell. This is the only process that is sensitive to DNase.
Transduction transfers DNA that is enveloped by a phage protein coat. This DNA is a fragment
of the donor chromosome.
Conjugation is the only transfer that requires Cell-to-Cell contact between donor and
recipient. Conjugation uses a specialized structure called a pilus (present only on the donor
cell) to transfer the DNA from cell-to-cell.
Describe conjugation between an F+ and F- cell Correct Ans-1) Cells make contact: F pilus
of F+ cell contacts recipient F- cell.
2) Initiation of transfer: One strand of F plasmid is cut at the origin of transfer, meanwhile the
pilus retracts to bring the recipient cell closer.
, BIOS 260 Final Exam with Verified Solutions
3)Transfer: single strand of F plasmid moves into recipient cell. The complement is made as it
enters the recipient cell.
4)Transfer is complete: both cells are F+
Which cell types can participate in conjugation? Correct Ans-both gram + and gram -. Both
donor and recipient cells:
F+ --> F- resulting in F+
HFR--> F- resulting in F'
Define Hfr cell Correct Ans-
Define F+ cell Correct Ans-cell that contains the F plasmid, capable of producing the sex
pilus.
Define F- cell Correct Ans-a cell lacking F plasmid, is unable to form sex pilus.
Define F' cell Correct Ans-HFR cell makes contact with F- cell.
