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Chapter 2: Microbiology

Chapter 2: Microbiology

Postby admin » Fri Aug 27, 2010 1:37 am

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Page Bio-26 - Bacteria replication

Postby GOFORMED » Fri Nov 04, 2011 12:08 pm

The paragraph writes that in transduction, phages act as a vctor transferring DNA between bacteria.

I would like to clarify some points.
1) Does the phage here mean a virus? Does a phage always mean a virus in any context?
2) Followed by Q(1), does a bacterium use a virus as the 'vector' to transfer genetic information to another bacterium?
3) Followed by Q(1) and (2), is the vector a virus or a bacterium? In any context, is a vector always a virus?
4) An overall question; without a virus, can a bacterium undergo genetic recombination?
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Postby goldstanda3269 » Sat Nov 05, 2011 8:56 am

1) Does the phage here mean a virus? Does a phage always mean a virus in any context?


As described in BIO 2.1, the definition of a phage (= bacteriophage) is a virus which infects bacteria. So yes, a phage is always a virus.

2) Followed by Q(1), does a bacterium use a virus as the 'vector' to transfer genetic information to another bacterium?


Yes, sometimes. (BIO 2.2)

3) Followed by Q(1) and (2), is the vector a virus or a bacterium? In any context, is a vector always a virus?


The book says "phages act as a vector" thus the virus (phage) is acting as a vector. The context is just that the vector is a carrier.

No, vector does not equal virus. This discussion is beyond the scope of the GAMSAT. A vector is a carrier (like a mosquito) that can transfer an infection (i.e. malaria) from one host to another (i.e. human).

4)
An overall question; without a virus, can a bacterium undergo genetic recombination?


Yes since recombination can also occur through transduction or conjugation under certain circumstances. Again, this is beyond the GAMSAT and certainly no a question type that they would ask.

Of the 4 ACER booklets, it would be of value to set aside 3 for when you are ready for timed testing. But take one of the half length booklets as early as possible, and work through all the biology questions. This will give you context to what you are learning and it will prevent you from looking for details. Also, of course, don't forget to do the chapter review questions available for free online with the book.
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Re: Chapter 2: Microbiology

Postby horbowiec.7527 » Wed Jun 30, 2021 11:32 am

This is regarding BIOLOGY Chapter 2 Worked solution for Q14:

The explanation mentions we need 2 trials (which is what answer choices are giving) but then further explanation suggests 4 trials:

2 in which the phage DNA is damaged
1 trial with no damage to bacterial DNA
1 trial with damage to bacterial DNA

I think I am reading it wrong...
Just to confirm Answer choice A is correct because to calculate relative magnitude of bacteria-mediated phage repair we need control group where bacteria was not irradiated (Trial III) & and experimental group were bacteria was irradiated (Trial IV) & in both of those trials the number for phage irradiation which is a variable should be kept the same?

Regards,
Ania
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Re: Chapter 2: Microbiology

Postby goldstanda3269 » Wed Jun 30, 2021 10:20 pm

horbowiec.7527 wrote:This is regarding BIOLOGY Chapter 2 Worked solution for Q14:

The explanation mentions we need 2 trials (which is what answer choices are giving) but then further explanation suggests 4 trials:

2 in which the phage DNA is damaged
1 trial with no damage to bacterial DNA
1 trial with damage to bacterial DNA

I think I am reading it wrong...
Just to confirm Answer choice A is correct because to calculate relative magnitude of bacteria-mediated phage repair we need control group where bacteria was not irradiated (Trial III) & and experimental group were bacteria was irradiated (Trial IV) & in both of those trials the number for phage irradiation which is a variable should be kept the same?


Yes!

You made an accurate summary.

But, to address the 4 vs 2 trial issue: it is only 2 trials (III and IV). As you can see from Table 1, Trial III is the control with non-irradiated bacteria AND radiated phage (this must be done together, otherwise we do not know the effect of one on the other). Trial IV has irradiated bacteria AND radiated phage. Now we can discover the degree to which bacteria are repairing phage DNA.
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