Bacterial Conjugation
Summary
TLDRBacterial conjugation is a direct cell-to-cell genetic transfer process requiring contact, facilitated by the F factor, a fertility factor in bacteria. F+ cells, containing the F factor, form a pilus to connect with F- recipient cells. The F factor is cut at the origin of transfer, and the T DNA strand is transferred via a pilus-linked exporter. Once in the recipient, the T DNA replicates, and both cells become F+, capable of further conjugation.
Takeaways
- π Bacterial conjugation is a genetic transfer process between bacterial cells that requires direct cell-to-cell contact.
- π Conjugation can occur between cells of the same species or between different species.
- π΅ The F factor, a small DNA circle or plasmid, is essential for bacterial conjugation and is referred to as the fertility factor.
- π Bacteria containing the F factor are designated as F+ (donor cells), while those without it are F- (recipient cells).
- π The F+ cell produces a pilus, a structure that connects with a recipient cell to initiate conjugation.
- βοΈ The F factor is cut at the origin of transfer by a relaxer protein assembly, which associates with the T (transferred) DNA strand.
- π The relaxer protein complex, along with the T DNA strand, is recognized and transferred to the exporter complex in the F+ cell.
- π The exporter complex pumps the T DNA-relaxer complex into the recipient cell through the pilus.
- π During transfer, the T DNA is replicated in the donor cell, ensuring that both donor and recipient cells end up with a double-stranded copy of the F factor.
- π After the transfer, both the original and recipient cells become F+, capable of conjugating with other cells.
Q & A
What is bacterial conjugation?
-Bacterial conjugation is a process of genetic transfer between bacterial cells that requires direct contact between the cells.
Can conjugation occur between different species of bacteria?
-Yes, conjugation can occur between cells of the same species or even between cells of two different species.
What is the role of the F factor in bacterial conjugation?
-The F factor, or fertility factor, is a small DNA circle or plasmid required for conjugation.
How are bacteria with and without the F factor distinguished?
-Strain of bacteria containing the F factor are called F+, while those without it are called F-.
What structure does an F+ cell produce to initiate conjugation?
-An F+ cell produces a structure called a pilus to connect with another recipient cell to begin conjugation.
What is the origin of transfer and its role in conjugation?
-The origin of transfer is a specific region on the F factor where it is cut to initiate the transfer of genetic material.
What is the function of the relaxer protein complex in conjugation?
-The relaxer protein complex cuts the F factor at the origin of transfer and associates with the T DNA strand to be transferred.
How is the T DNA relaxase complex transferred to the recipient cell?
-The T DNA relaxase complex is recognized by a coupling factor and transferred to the exporter complex in the F+ cell, which pumps it into the recipient cell.
What happens to the T DNA once it is transferred to the recipient cell?
-Once the entire T DNA molecule is transferred to the recipient cell, the relaxase joins the ends to make a circular DNA molecule.
How does the F factor DNA become double-stranded in the donor and recipient cells?
-The F factor DNA is replicated to become double-stranded in the donor cell as the T DNA is being transferred to the recipient cell.
What is the outcome for the cells after the conjugation process?
-After the connection through the pilus is released, each cell, now containing a double-stranded copy of the F factor, becomes an F+ cell capable of conjugating with other cells.
Outlines
π¬ Bacterial Conjugation Process
Bacterial conjugation is a genetic transfer process that requires direct contact between bacterial cells. It can occur within the same species or between different species. The F factor, a small DNA circle or plasmid, is essential for this process. Bacteria with the F factor are termed F+ (donors), while those without are F- (recipients). Conjugation begins when an F+ cell produces a pilus to connect with an F- cell. The F factor is cut at the origin of transfer by a relaxer complex, which then transfers a single-stranded T DNA to the recipient cell via a coupling factor and exporter complex. Once in the recipient cell, the T DNA is replicated to become double-stranded, and both cells become F+, capable of further conjugation.
Mindmap
Keywords
π‘Bacterial Conjugation
π‘Fertility Factor (F Factor)
π‘Pilus
π‘Origin of Transfer
π‘Relaxer Cell
π‘T DNA Strand
π‘Coupling Factor
π‘Exporter Complex
π‘Double-Stranded DNA
π‘F+ Cell
Highlights
Bacterial conjugation is a process of genetic transfer between bacterial cells requiring direct contact.
Conjugation can occur within the same species or between different species of bacteria.
A small DNA circle or plasmid called the F factor is necessary for conjugation.
Bacteria containing the F factor are referred to as F+, while those without are F-.
An F+ cell, or donor, produces a pilus to connect with a recipient cell to initiate conjugation.
The F factor is cut at the origin of transfer by a protein assembly known as the relaxosome.
The relaxosome associates with the T DNA strand, which is to be transferred.
Accessory proteins of the relaxosome, called Lamar, are involved in the transfer process.
A portion of the relaxosome, called the relaxation complex, remains attached to the T DNA.
The T DNA-relaxosome complex is recognized by a coupling factor for transfer.
The exporter complex in the F+ cell, connected to the pilus, pumps the T DNA-relaxosome complex into the recipient cell.
Once the T DNA molecule is transferred, the relaxosome joins the ends to form a circular DNA molecule.
The T DNA is replicated to become double-stranded in the recipient cell.
In the donor cell, the F factor DNA is also replicated to become double-stranded during the transfer process.
After the transfer, both cells have a complete double-stranded copy of the F factor.
The cells disconnect from each other, and each becomes an F+ cell capable of conjugating with other cells.
Transcripts
bacterial conjugation is a process of
genetic transfer between bacterial cells
that requires direct contact between the
cells many but not all species of
bacteria can conjugate conjugation can
occur between cells of the same species
or even between cells of two different
species a small DNA circle or plasmid
called the F factor is required for
conjugation the F factor stands for
fertility factor strains of bacteria
containing the F factor are called
F plus those without it are called F
minus and F plus cell or a donor
produces a structure called a pilus to
connect with another recipient cell to
begin conjugation the F factor is cut at
a specific region called the origin of
transfer by a protein assembly called
the relaxer cell which associates with a
strand to be transferred or the T DNA
strand accessory proteins of the
relaxants Lamar released but a portion
of the relaxer zone called the
relaxation
remains attached to the T DNA this t DNA
relaxes complex is recognized by a
coupling factor and transferred to the
exporter a complex in the f+ cell that
is contiguous with the pilus the
exporter pumps the T DNA relaxes complex
into the recipient cell once the entire
T DNA molecule is transferred to the
recipient cell relaxes joins the ends to
make a circular DNA molecule as the T
DNA is transferred to the recipient cell
it is replicated to become double
stranded in the donor cell the F factor
DNA was also replicated to become double
stranded
this actually occurred as the T DNA was
being transferred to the recipient cell
in the end most cells wind up with a
complete double-stranded copy of the F
factor their connection through the
pilot is released and each is now an F+
cell that can go on to conjugate with
other cells
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