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DavidYorkshireFTW
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#2821
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#2821
(Original post by Mocking_bird)
So we dont have to know about it in terms of gene therapy? I'm confused

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I assumed it was used as an example for gene therapy, I don't think so; what i just said is out of the spec knowledge you can either use for inorganic/organic ions or causes of disease :L
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F1's Finest
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#2822
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#2822
(Original post by feelinginfinite)
Oh okay. So it's enough to simply say "the DNA is extracted from a sample of blood/hair", then "this DNA sample is then cut up by restriction endonucleases, where the enzymes cut near core sequences"? Okay got it, thanks

Any chance you can help with the other question in bold I had? I'm confused as to when the DNA probes are added; are they added after Southern blotting (Nelson thornes book pg 277 says they're added in "hybridisation", after southern blotting, "probes are now used to bind DNA sequences)... But I'm confused- why would probes be used after UV light fixes the DNA fragments on to the nylon membrane? Doesn't that imply that there are radioactive probes before southern blotting? :confused:

Edit: Ok I've + repped you too much/recently so I'll try again later. At least it proves you're being helpful enough to be +ve repped so much
Yeah, just saying that will be enough

The purpose of adding the DNA probes are so that you can identify the DNA bands on the nylon membrane/film.

Remember that you can't see DNA bands using the naked eye, therefore a mixture of DNA probes (which are fluorescently labelled) are used to bind to the DNA fragments on the nylon membrane/film. When we then add UV light, we can see the bands!

To confirm, the probes are added after the DNA fragments have moved, according to their size.
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rommy123
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#2823
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#2823
can someone please explain the Sanger method?
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pjanoo
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#2824
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#2824
(Original post by Anjna)
what is the function of the corpus luteum in the menstrual cycle? anyone?
The corpus luteum releases progesterone.

This will maintain the thickening of the uterus lining, so it's ready for implantation of the fertilised egg. Progesterone will also inhibit the secretion of FSH by the pit. gland, so no more follicles are released/eggs produced until the current egg has left the body via menstruation or birth.
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GinaS
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#2825
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#2825
Can somebody help me with the essay "the transfer of energy between different organisms and between those organisms and their environment" ? Or just a general transfer of energy one?


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aWildPidgey
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#2826
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#2826
Regulation of heart rate anyone? :3
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Hippokrates
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#2827
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#2827
(Original post by rommy123)
can someone please explain the Sanger method?
http://smcg.ccg.unam.mx/enp-unam/03-.../secuencia.swf
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Jono_S6
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#2828
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#2828
(Original post by mcollin1)
This may have been asked before, really haven't been up to date on this thread, but June 2012, Question 7.

its about root cells and IAA, my idea of hell...

Mark Scheme:
1. IAA/auxin moves to lower
side / more IAA/auxin on
lower side;
2. Lower side grows
less/slower / upper side
grows more /faster / inhibits
growth on lower side;

Problem is I always though IAA stimulated growth, not inhibited it? or is this different in root cells? :confused:


IAA promotes growth in stems by causing cells to elongate, and inhibits growth in root cells. This is why you end up with both positive phototropism in stems and positive geotropism in roots That's my understanding anyway!
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pjanoo
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#2829
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#2829
What have you lot found to be the most efficient way of preparing for the essay so far? Any methods that have left you feeling ready and confident, without having to read massive chunks of the AS + A2 textbook?
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Hippokrates
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#2830
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#2830
(Original post by aWildPidgey)
Regulation of heart rate anyone? :3
SAN → AVN → bundle of His /Purkyne fibres;
Impulses / electrical activity(over atria);
Atria contract;
Non-conducting tissue (between atria and ventricles);
Delay (at AVN) ensures atria empty/ ventricles fill before ventricles contract;
Ventricles contract from apex upwards;
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estudiante_numero1
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#2831
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#2831
Heyy guys!

I am also sitting this paper on Monday. Feeling okay about the BIOL5 content on the whole, just quite concerned about the essay haha! Praying we get a lovely broad title!

Just a quick question about the marking of the essay...I've looked at the past paper essay titles and mark schemes and wondered how many points you need to include from the list of suggested points in order to score 14/16 in the content section (I appreciate that the last two marks are for off-specification points)?

Any help would be much appreciated! Thanks.


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Hippokrates
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#2832
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#2832
(Original post by estudiante_numero1)
Heyy guys!

I am also sitting this paper on Monday. Feeling okay about the BIOL5 content on the whole, just quite concerned about the essay haha! Praying we get a lovely broad title!

Just a quick question about the marking of the essay...I've looked at the past paper essay titles and mark schemes and wondered how many points you need to include from the list of suggested points in order to score 14/16 in the content section (I appreciate that the last two marks are for off-specification points)?

Any help would be much appreciated! Thanks.


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If you do 4 up to 6 mark question standard you're good
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stoppy123
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#2833
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#2833
(Original post by rommy123)
can someone please explain the Sanger method?
4 tubes containing DNA polymerase, the required fragment, free nucleotides and a terminator base, whether it be A, G, T or C.

Let's say the dna fragment you want is CGAATCGTTA.

In the first tube, using terminator A, you'll get fragments CGA, CGAA, CGAATCGTTA.
In the second tube, using terminator G, you'll get fragments CG CGAATCG
In the third tube, using terminator T, you'll get fragments CGAAT CGAATCGT CGAATCGTT
In the fourth tube, using terminator C, you'll get fragments C CGAATC

When these fragments are seperated on a gel, it will show the order in which the bases go, as you can read from the bottom up.
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aWildPidgey
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#2834
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#2834
(Original post by Hippokrates)
SAN → AVN → bundle of His /Purkyne fibres;
Impulses / electrical activity(over atria);
Atria contract;
Non-conducting tissue (between atria and ventricles);
Delay (at AVN) ensures atria empty/ ventricles fill before ventricles contract;
Ventricles contract from apex upwards;
Thanks but I mean the whole medulla oblongata thing
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Hippokrates
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#2835
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#2835
(Original post by stoppy123)
4 tubes containing DNA polymerase, the required fragment, free nucleotides and a terminator base, whether it be A, G, T or C.

Let's say the dna fragment you want is CGAATCGTTA.

In the first tube, using terminator A, you'll get fragments CGA, CGAA, CGAATCGTTA.
In the second tube, using terminator G, you'll get fragments CG CGAATCG
In the third tube, using terminator T, you'll get fragments CGAAT CGAATCGT CGAATCGTT
In the fourth tube, using terminator C, you'll get fragments C CGAATC

When these fragments are seperated on a gel, it will show the order in which the bases go, as you can read from the bottom up.
The terminator sequences should be complimentary shouldn't they?
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lucy3003
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#2836
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#2836
Hey, does anyone know some general answers to questions that often come up in exams, where there's a specific wording they always look for? As there's only 4 papers on AQA website, it's hard to find!
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stoppy123
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#2837
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#2837
(Original post by Hippokrates)
The terminator sequences should be complimentary shouldn't they?
What do you mean?
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Med_me
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#2838
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#2838
(Original post by Hippokrates)
Thanks!
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ameelia22
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#2839
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#2839
(Original post by rommy123)
can someone please explain the Sanger method?
4 test tubes.
Each have:
  1. Lots of single stranded DNA fragments (from the DNA that your trying to sequence)
  2. DNA polymerase
  3. Lots of other nucleotide bases, A G C T
  4. and a primer


In addition to this, each of the 4 test tubes, have a different terminator nucleotide.

So, Test Tube 1 will have the above list, and several terminator nucleotide bases of A.
Test Tube 2 will have all of the above list, and and several terminator nucleotide bases of G and so on.

Now, these are all merrily happy in each of their respective test tubes. Like "Ingredients" if you must.

The primer is able to start the DNA synthesis by binding onto the ends of the sequence, and is also radioactively labeled.
The DNA polymerase is then able to continue the synthesis, attaching the complimentary nucleotides.

Whether or not a terminator nucleotide or a normal nucleotide is attached is completely random. So you might end up with a DNA fragment which goes,

Primer - A, G, G, Terminator C. No other nucleotides can be attached after the terminator nucleotide. The terminator nucleotide could be the first nucleotide or the last. It's entirely random.

This means that in each of the 4 test tubes, you will have DNA fragments of varying lengths. But, in each test tube, they will all end in the same nucleotide.

Then using gel electrophoresis you separate each of them out.

Your then left with something that looks like this:
Name:  47672-004-4E16B61F.jpg
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Size:  25.1 KB

Now looking at that, the sequence is: CAAGTAGTGGCAA

Does that help?
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stoppy123
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#2840
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#2840
(Original post by Hippokrates)
The terminator sequences should be complimentary shouldn't they?
OH, hahahaha massive mistake, yeah they should be :facepalm: haah
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