generalized vs specialized transduction

[MudPhud20XX]

---

Members don't see this ad.

A culture of bacteria is incubated with bacteriophages and then centrifuged to pellet the bacterial cells. The liquid above the cells is then added to new cultures of bacteria. In these new cultures, 5 clones of bacteria are seen to acquire 5 different new genetic traits. Which of the following best describes this phenomenon?

What do you guys think? pls with explanation.

 

[Nabin]

Generalized transduction?

In the first experiment, bacteriophages have inserted their DNA into the bacterial cells and the DNA of that bacteria has now broken down by the phage enzymes into many different portions. Phage DNA then synthesize new coat and carry the bacterial DNA portions. In the second experiment, when these bacteriophages bearing different bacterial DNA sequences infect new clones, they acquire different genetic trait all unique due to the different DNA portions that were formed in the first place by the lytic phage. Generalized transduction is a random event and any portion can be taken by the bacteriophages so I am thinking that is responsible for the different genetic traits acquired by the new colony bacteria.

 

[MudPhud20XX]

So if this was a specialized, could you give an example?

Generalized transduction?

In the first experiment, bacteriophages have inserted their DNA into the bacterial cells and the DNA of that bacteria has now broken down by the phage enzymes into many different portions. Phage DNA then synthesize new coat and carry the bacterial DNA portions. In the second experiment, when these bacteriophages bearing different bacterial DNA sequences infect new clones, they acquire different genetic trait all unique due to the different DNA portions that were formed in the first place by the lytic phage. Generalized transduction is a random event and any portion can be taken by the bacteriophages so I am thinking that is responsible for the different genetic traits acquired by the new colony bacteria.

 

[Nabin]

So if this was a specialized, could you give an example?

If this were a specialized transduction, then a bacteriophage would insert into a specific site on the bacterial DNA. And when induced, new defective viral particles would be produced each having the same flanking bacterial chromosome close to the point where bacteriophage DNA inserted in the first place. So, its specific, not random like in a generalized transduction. So, I guess when they infect new bacteria, the bacteria would acquire similar genetic properties contributed by the specific flanked bacterial DNA regions. That's what I think about this.

It'd be nice if someone else too shed their opinion on this. What is your analysis?

 

[aspiringmd1015]

in generalized, the bacteria which acquires a bacteriophage, does it get to express those genes in that bacteriophage?

 

[Nabin]

in generalized, the bacteria which acquires a bacteriophage, does it get to express those genes in that bacteriophage?

It depends whether the phage is undergoing a lysogenic cycle or the lytic cycle, which in turn depends on the characteristics of the phage. In the lytic cycle, after phage infects and replicates itself, the host cell is lysed when the number has reached too large to fit inside the host. In the lysogenic cycle, phage DNA gets inserted into the bacterial DNA (forming prophage) and when that bacteria replicates its daughters will carry the phage genes who will have the potential to form new phages.

 

[Dr Z AU]

I thought to bump this read rather rather than create a new one - hopefully this is OK.

I would like to ask if my information or thinking is correct as I've been somewhat confused with Specialized Transduction and the gaining of various toxins through this mechanism.

a) The bacteriophage infects a bacterial strain that produces the toxin and then transfers these genes over to another bacteria, greatly increasing the spread of this gene.
b) The bacteriophage itself is responsbile for coding the toxin and is incorporated into the chromosome of the bacteria and during the lysogenic phase will replicate along with the bacteria.

But now that I read this it's like 2 parts of the various viral cycles - (a) = lytic phase and (b) = lysogenic phase.

The main part I'm confused about is whether these toxins are transferred from bacterial strains that already carry the gene to produce the toxin or if the viral DNA itself codes for these toxins ?

EDIT: On 2nd thought it seems most logical that a virus will infect a toxin-producing strain, incorporate into the chromosome (lysogenic phase), and then when active will replicate + incorporate the toxin producing DNA and carry that on to other bacteria. (lytic phase).

Thank you

 

[tasar1898]

Yeah some viruses through excision mistakes somewhere in time incorporated the toxin DNA in their own Genome and are transcribing it even in their latent form in the subsequent bacteria they infect

 

[Phloston]

A culture of bacteria is incubated with bacteriophages and then centrifuged to pellet the bacterial cells. The liquid above the cells is then added to new cultures of bacteria. In these new cultures, 5 clones of bacteria are seen to acquire 5 different new genetic traits. Which of the following best describes this phenomenon?

What do you guys think? pls with explanation.

Generalized is just a lytic process without lysogeny. Specialized is lysogenic with accompanying flanking of bacterial genes upon reemergence.

Therefore I'd think specialized wouldn't happen that quickly (i.e., you need enzymes to do their magic) and in a quick centrifugation we'd be looking at a mere lytic process.

In both cases the phages will leave the bacterial cells with bacterial nucleic acid.

 

[AxiomaticTruth]

Correct me if I'm wrong, but to me this would be generalized because the bacterial DNA is cut into many different pieces hence why there are 5 different strains in 5 colonies in the second experiment. If this was specialized, then a the phage's DNA would be excised with only flanking bacterial DNA and replicated, thus in the second experiment there should only be 1 strain across the 5 colonies.

 

[tasar1898]

Just reading the words "bacteriophage" and "different traits" --> generalized transduction