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JenLivYoung
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#1981
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#1981
(Original post by marleyxd)
For part a (i) how will it make 2 fragments if its only digested at one site? Because its a plasmid surely it will only form one fragment?
There's already a restriction site in the plasmid, as seen in the diagram, so the DNA must also have one so there are two places where it's cut, sorry I didn't mention that bit
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JoshL123
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#1982
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#1982
Guys, do you think all of the old essays have a potential of coming up? It just feels that some of them are just too narrow :/
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F1's Finest
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#1983
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#1983
(Original post by JoshL123)
Guys, do you think all of the old essays have a potential of coming up? It just feels that some of them are just too narrow :/
I doubt the essays from the actual past papers (for the current spec) would come up. But don't count it out!
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JoshL123
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#1984
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#1984
(Original post by James A)
I doubt the essays from the actual past papers (for the current spec) would come up. But don't count it out!
I was thinking in relation to the old spec essays :/
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krane
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#1985
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#1985
Am i right in thinking that we only have 3 past papers and a specimen paper?

Also dreading the fact that this exam is on the same day as edexcel psychology, makes the whole thing a lot harder!
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F1's Finest
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#1986
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#1986
(Original post by JoshL123)
I was thinking in relation to the old spec essays :/
meh, it could be!

What sort of titles are you referring to? I just skim the papers for the questions, but I don't look at the essay questions.
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ilanagrand
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#1987
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#1987
anyone got an essay on the important of water?
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JoshL123
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#1988
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#1988
(Original post by James A)
meh, it could be!

What sort of titles are you referring to? I just skim the papers for the questions, but I don't look at the essay questions.
Stuff on, fore example, How amino acids get from protein to a persons food, and the role of pigments in organisms. I swear that these kind of essays hold little 'synoptic' elemnets :/
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F1's Finest
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#1989
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#1989
(Original post by JoshL123)
Stuff on, fore example, How amino acids get from protein to a persons food, and the role of pigments in organisms. I swear that these kind of essays hold little 'synoptic' elemnets :/
Damn

The thing with those questions is that you are a little restricted on what you can talk about.

The first one about amino acids you mentioned, we can only talk about:

polypeptides
digestion (processes involved)
Hydrolysis

That's about it.

IF you look at the current spec questions though, they have questions where there are many topics you can bring in. Like the recent one about shapes and fitting together, there's alot you can talk about from our spec (and of course, bring in some off topic stuff).

Also, remember that the old spec has different topics that the kids that sat the exams back then, had to learn.

So they will have to ask us a question, which has a common theme amongst the entire A-Level spec that we learnt.
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starfish232
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#1990
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#1990
Hi, could someone please just help me with some questions I have about muscle contraction:

1. Is the sliding filament theory to do with describing the process of muscle contraction or is to do with changes in the sarcomere when muscle contraction happens?
2. In Q2b of the June 2012 paper, the answer is between 29545-30455 but I got an answer of 25909 and I'm not exactly sure what the image measurement is suppose to be.
I got 114(mm) x 1000 / 4.4 which equaled to about 25909.

Thanks
http://filestore.aqa.org.uk/subjects...W-MS-JUN12.PDF
http://filestore.aqa.org.uk/subjects...5-QP-JUN12.PDF
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currydud
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#1991
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#1991
(Original post by starfish232)
Hi, could someone please just help me with some questions I have about muscle contraction:

1. Is the sliding filament theory to do with describing the process of muscle contraction or is to do with changes in the sarcomere when muscle contraction happens?
2. In Q2b of the June 2012 paper, the answer is between 29545-30455 but I got an answer of 25909 and I'm not exactly sure what the image measurement is suppose to be.
I got 114(mm) x 1000 / 4.4 which equaled to about 25909.

Thanks
http://filestore.aqa.org.uk/subjects...W-MS-JUN12.PDF
http://filestore.aqa.org.uk/subjects...5-QP-JUN12.PDF
1. its about the process of muscle contraction

2.I got the answer of 30455

magnification=image length/actual length
magnification=67000/2.2
=30454.545454..
=30455
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Tikara
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#1992
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#1992
guys, are there actin filaments inside a cell?
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currydud
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#1993
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#1993
(Original post by Tikara)
guys, are there actin filaments inside a cell?
yeah, a muscle cell
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Tikara
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#1994
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#1994
(Original post by currydud)
yeah, a muscle cell
I meant in non muscle cells sorry :rolleyes:
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samfreak
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#1995
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#1995
with regards to DNA sequencing and gel electrophoresis on page 268 it says "In this way the whole sequence of bases on the terminator nucleotides was found to be AGCTTGAC and this is the sequence on one of the strands of the newly formed DNA." i thought that it was the sequence of the DNA we we originally had that we were trying to find though and not the sequence of the terminator nucleotides. Therefore the sequence we would be trying to find would be the opposite bases to the terminator nucleotide sequence?
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Tikara
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#1996
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#1996
(Original post by currydud)
yeah, a muscle cell
I found out if anyones wondering - yeah they're found in non-muscle cells :P

Spoiler:
Show

from http://www.britannica.com/EBchecked/...ctin-filaments

Actin is also present in non-muscle cells, where it forms a meshwork of filaments responsible for many types of cellular movement. The meshwork consists of actin filaments that are attached to the cell membrane and to each other. The length of the filaments and the architecture of their attachments determine the shape and consistency of a cell. A large number of accessory proteins bind to actin, controlling the number, length, position, and attachments of the actin filaments. Different cells and tissues contain different accessory proteins, which accounts for the different shapes and movements of different cells. For example, in some cells, actin filaments are bundled by accessory proteins, and the bundle is attached to the cell membrane to form microvilli, stable protrusions that resemble tiny bristles. Microvilli on the surface of epithelial cells such as those lining the intestine increase the cell’s surface area and thus facilitate the absorption of ingested food and water molecules. Other types of microvilli are involved in the detection of sound in the ear, where their movement, caused by sound waves, sends an electrical signal to the brain.

Wait, microvilli are made up of actin filaments?!

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havana-affair
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#1997
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#1997
regarding gene therapy,

does both gene replacement and gene supplementation fall under somatic-cell gene therapy
and germ-line therapy is a separate thing just for fertilized eggs?
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starfish232
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#1998
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#1998
(Original post by currydud)
1. its about the process of muscle contraction

2.I got the answer of 30455

magnification=image length/actual length
magnification=67000/2.2
=30454.545454..
=30455
oh ok thanks.

I got confused since it said the whole diagram rather than just one sarcomere. Also, think my measuring is wrong because the question was in another pack rather in the exam paper it's originally from so size might be smaller of the diagram.
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starfish232
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#1999
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#1999
(Original post by havana-affair)
regarding gene therapy,

does both gene replacement and gene supplementation fall under somatic-cell gene therapy
and germ-line therapy is a separate thing just for fertilized eggs?
it should be since somatic-cells refers to any other cell other than the gametes.
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6274ward
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#2000
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#2000
Concerning essays, does anyone know were I should be looking to find relevant information? How much detail needs to go into these parts of the essay?
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