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genetic engineering- not understanding some concepts

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genetic engineering- not understanding some concepts

Postby radioinahole » Fri Oct 21, 2011 2:38 pm

I have a list of questions I have while studying for my course called Introduction to genetic engineering ad I have a couple of questions i hope I can get answered. Thank you :)

1. When making mRNA to DNA, we use reverse transcriptase. When the cDNA is made and we remove the mRNA by adding alkali. Is the complementary DNA strand now made using DNA Polymerase I or III?

2. In genetic engineering, when a recombinant dna enters a host cell, it either integrates, disintegrates or remains as an episome. Does the reason it disintegrates is because the host cell can detect it doesn't have the same methylation sequence and cuts it via host controlled restriction??

3. In genetic engineering, when we want to clone a gene, I have taken in class that we don't use PCR all the time because to use it, you have to know the sequence of the annealing sites. I don't understand this because when you want to cut a plasmid to use as a vector, should we know the sequence anyway, to make sure we dont cut a gene or insert the foreign dna between a gene hat is important for the plasmid to actually work? For example, M13 phage has 10 genes and we shouldnt cut any of those genes otherwise we cant use it as a vector, right? So dont we know the sequence, so why cant we always use PCR?

I have a quiz coming up in 5 days and I was wondering if there are any good sites for solving questions about ligation, restriction endonuclease, blunt and sticky ends and pUC8 plasmids and whatnot. If you know any sites that have answers as well as questions please let me know otherwise I wont be able to know if I did it right or wrong. It is ok if the questions are multiple choice. I am looking for mostly questions where they give you sticky ends or the RE enzyme ad tell you if you can ligate it or how would you use it blah blah
Thanks for your time :)
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Postby JackBean » Sun Oct 23, 2011 12:47 pm

It's usually some bacterial polymerase.

May be, but also naked DNA is something bad (usually naked DNA with free ends comes from virus or pathogenic bacteria;), so the cell controls it.

I don't get much the question. Is it related to gene expression or just searching the gene?

Cis or trans? That's what matters.
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Postby aptitude » Sun Oct 23, 2011 9:47 pm

1. Bacterial polymerase

2. Yes

3. Gene cloning can be used for other studies, such as studying gene expression, and making genomic libraries, which PCR cannot be used for.
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