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A2 Biology OCR June 2015 Revision Thread

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Has anyone done the evaluative task for maggots/lice/invertebrates? If so please could you give me some guidance? :-(
Original post by TheLegalDealer
The ratio is 1:2:1


Yep, Yua's right. Use the ratio they give you in the question.
Anyone got the 2014 F215 paper and MS, not on OCR website
For the production of the insulin gene would I have to state the role of Reverse transriptase to produce cDNA or can I say that restrictive enzymes are used to extract the insulin gene etc .
Original post by TheLegalDealer
For the production of the insulin gene would I have to state the role of Reverse transriptase to produce cDNA or can I say that restrictive enzymes are used to extract the insulin gene etc .


Yes you do need to state that reverse transcriptase is used. *Restriction enzymes are used on the plasmid, but sticky ends are added to the cDNA as far as I know.
Lactose permease and co. Are known as inducible enzymes; only synthesised when required
Original post by AnnekaChan173
Yes you do need to state that reverse transcriptase is used. *Restriction enzymes are used on the plasmid, but sticky ends are added to the cDNA as far as I know.


I thought you could use either/or method or am I being a noob?

So if we use restriction enzymes, we can isolate the fragment for insulin and the sticky end will be complementary to the plasmid. Is that correct? Am I righe in thinking we don't need reverse transcriptase in this context?

Because I thought using reverse transcriptase is just making cDNA from mRNA, treating it with DNA polymerase to get both strands and you'll have the isolated insulin gene? But then I suppose you'll need to use endonucleases to insert the gene inot the plasmid... hmm
Original post by ChoccyPhilly
I thought you could use either/or method or am I being a noob?

So if we use restriction enzymes, we can isolate the fragment for insulin and the sticky end will be complementary to the plasmid. Is that correct? Am I righe in thinking we don't need reverse transcriptase in this context?

Because I thought using reverse transcriptase is just making cDNA from mRNA, treating it with DNA polymerase to get both strands and you'll have the isolated insulin gene? But then I suppose you'll need to use endonucleases to insert the gene inot the plasmid... hmm


Ok I've just woken up from a nap so if I've written something stupid I'm sorry. The textbook states the mRNA to cDNA option for insulin specifically, but if it were another gene, I would state the other version when you cut using restriction enzymes unless otherwise stated. Because it's difficult to extract the DNA from the beta cells in the Islets of Langerhans, we use reverse transcriptase. I think the idea is, because so much insulin is being produced so that it can be secreted, there must be a lot of mRNA readily available. When you treat it with DNA polymerase, you're just adding the sticky ends (the enzyme makes phosphodiester bonds between the cDNA and free nucleotides).
Original post by AnnekaChan173
Ok I've just woken up from a nap so if I've written something stupid I'm sorry. The textbook states the mRNA to cDNA option for insulin specifically, but if it were another gene, I would state the other version when you cut using restriction enzymes unless otherwise stated. Because it's difficult to extract the DNA from the beta cells in the Islets of Langerhans, we use reverse transcriptase. I think the idea is, because so much insulin is being produced so that it can be secreted, there must be a lot of mRNA readily available. When you treat it with DNA polymerase, you're just adding the sticky ends (the enzyme makes phosphodiester bonds between the cDNA and free nucleotides).


Oh, I'm not denying that but what im wondering is if insulin extraction specifically requires reverse transcriptase because my book is quite vague and just suggests using reverse transcriptase and/or restriction enzymes as two different techniques. From my point of view, it seems you could extract the insulin gene using just restriction enzymes but I'd hate to miss out on a lot of marks because I didnt go on about cDNA but maybe that relates to the sheer quantity of mRNA strands for insulin
Original post by ChoccyPhilly
Oh, I'm not denying that but what im wondering is if insulin extraction specifically requires reverse transcriptase because my book is quite vague and just suggests using reverse transcriptase and/or restriction enzymes as two different techniques. From my point of view, it seems you could extract the insulin gene using just restriction enzymes but I'd hate to miss out on a lot of marks because I didnt go on about cDNA but maybe that relates to the sheer quantity of mRNA strands for insulin


It says it in the Purple textbook.

I've done a question and it has given marks for saying reverse transcriptase is used, making cDNA from RNA etc, so I personally wouldn't leave it out.
Original post by ChoccyPhilly
Oh, I'm not denying that but what im wondering is if insulin extraction specifically requires reverse transcriptase because my book is quite vague and just suggests using reverse transcriptase and/or restriction enzymes as two different techniques. From my point of view, it seems you could extract the insulin gene using just restriction enzymes but I'd hate to miss out on a lot of marks because I didnt go on about cDNA but maybe that relates to the sheer quantity of mRNA strands for insulin


Wow I have no clue what you guys are on about! YOU GUYS ARE TOoo CLEVER! share your tips loooool
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Original post by games211
Wow I have no clue what you guys are on about! YOU GUYS ARE TOoo CLEVER! share your tips loooool

you need to revise
Original post by Yua
you need to revise


I forget everything the next day/........
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Original post by games211
I forget everything the next day/........

then revise again
Original post by games211
Wow I have no clue what you guys are on about! YOU GUYS ARE TOoo CLEVER! share your tips loooool


It's biotech haha, None of us get it :') Listen in class hahahaha, ask questions, learn content before attempting questions etcetc, you have time though since it's all unit 5
Original post by games211
Wow I have no clue what you guys are on about! YOU GUYS ARE TOoo CLEVER! share your tips loooool


No other way about it, just gotta sit down and grit it out but actually engage yourself, like reading the textbook and thinking about it rather than having your mind elsewhere and telling yourself that tire working hard when you're not. You remember it better that way
Reply 696
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can anyone explain linkage to me
If anybody need the June 2014 f214/f215 paper pm me


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Original post by cheeky 12
If anybody need the June 2014 f214/f215 paper pm me


Posted from TSR Mobile


http://www.thebiotutor.com/past-papers3.html
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Original post by bbadonde2

and the MS?

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