Edexcel A2 Biology Unit 5 (6BIO5) - 22/06/2011- OFFICIAL THREAD !

I can't believe I skipped this objective!!!

Explain how genes can be switched on and off by DNA transcription factors including hormones

Can someone please explain the key points to me? CGP mentioned homeostasis and temperature regulation with genes and Edexcel SNAB Revision guide mentioned drugs and genes!? WTFFF

yh me two I talked about stretch receptors first...and just chemo was mentioned

just always say x-receptors in the carotid body as they have every type lol

Just remember that hormones can cause increased production of proteins that can act as transcription factors. Transcription factors form a 'transcription initiation complex' which binds to the promoter region and allows the DNA to be transcribed. Without all the necessary factors, the DNA can't be transcribed. Obviously proteins can also act as repressor molecules, inhibiting transcription. And that's pretty much all you really have to know, there's that tiny bit in CGP about it, but there's no real detail anywhere..

Ahem.. Female

I think the main bits are you mention that all the transcription factors must combine in order to form a TIN (Transcription Initation Complex)

I think there's an example of Thyroxine or something which is involved in regulating temperature?

I can't believe I skipped this objective!!!

Explain how genes can be switched on and off by DNA transcription factors including hormones

Can someone please explain the key points to me? CGP mentioned homeostasis and temperature regulation with genes and Edexcel SNAB Revision guide mentioned drugs and genes!? WTFFF

beat me to it!

And also, do you have the mark scheme for the Jan 2010 paper

Heroine?!? or superwoman?!?

basically referring to how anabolic steroids and erythropoietin switch genes on and off.

in the case of anabolic steroids, it passes through cell surface membrane, binds with a receptor molecule within the cell and this complex becomes the transcription factor, switches on particular genes that changes the RNA, affecting the types and numbers of proteins produced. somehow linked to the build up of a massively muscular and honed physique.

erythropoietin, however, binds to receptor ON the cell surface membrane, activating a second messenger in the cytoplasm, triggering a protein kinase cascade (activation of several different proteins). its final product enters the nucleus and acts as a transcription factor, switches on genes linked to protein synthesis of enzymes needed for production of more RBC..

hope this helped! correct me if i'm wrong, anyone..

Don't know if this has been asked before but do we need to know all the growth factors and what they do : giberellin,cytokinins,ethene and abscisic acid?

haha!
And unfortunately, I was trying to look for one, but its only available online, and needs a teacher login..
If anyone manages to find it/log in, please let me know..

I can't believe I skipped this objective!!!

Explain how genes can be switched on and off by DNA transcription factors including hormones

Can someone please explain the key points to me? CGP mentioned homeostasis and temperature regulation with genes and Edexcel SNAB Revision guide mentioned drugs and genes!? WTFFF

Here's the Jan 2010 paper from the old spec. I removed my answers, which is why there are some blank spaces.

Do you have the Mark Scheme for it ?

Well I think someone forgot to mention the following(out of the 900+ posts):
1) Good Luck, try your best (110% is not physically possible )
2) Just keep thinking to yourself "I am never ever EVER going to look at this ever again" and think of the SNAB books burning

This kind of helped me going for these past few months