Edexcel A2 Biology Unit 5 (6BIO5) - 27/01/2011- OFFICIAL THREAD !

homeoboxes seems similar to transcription factors.
what are the differences between them?

for the similarities,
they act as transcription factors and regulates the gene duplication/ manipulation process.
they bind to promoter region, anything else?

I'm not actually sure! Is there a function or is it just the consequence of using chemical synapses? Electrical synapses are faster - not included in this syllabus - but they can't provide the same level of response complexity. Also, chemical synapses allow for there to be gain across the synapse, so that subsequent signals can get stronger or remain the same as they pass along to the next neurone. Where as impulses transfered using electrical synapses always get weaker.

I don't think we need to know that.

Hi Sophia92,

I posted this under another thread a couple of days ago. These I what I consider the main points from each section. I probably will not have time to go through every point in detail, but you are welcome to get back to me with any particular areas you have difficulty with and I will try my best to help.

From how genes evolve -
1) Understanding the different types of DNA mutation mentioned in the article - frame-shift, retroposition.
2) Understanding the concept of introns and exons.
3) What is Junk DNA and how is it linked to the ability to form new genes?
4) What factors act as obstacles to junk DNA being converted to a functional gene?
5) What is subfunctionalisation of a gene and how does it help with gene evolution?

From gene control
1) understanding the importance of switching genes on and off
2) understanding transcription control of genes (look at the SNAB textbook)
3) how activators and repressors control gene expression
4) the significance of genomic imprinting
5) the role of homeoboxes

any one got notes or answer for these questions plzzzz

whilst i know you don't need to know it, just to nip this in the bud. all of the stuff in bold is not true and that in red is sometimes the case but not always. neurones are so so so much more more complicated than youre giving them justice

What are the practicals for this?

Does anyone know whether synoptic questions will be mainly/entirely confined to the last 30 marks worth of questions on the article. Or whether they can/will include synoptic questions within the main body of the exam?

Could be either, hopefully not like last year and not just in article questions. Maybe we won't see any.

So... how's everyone (or anyone for that matter) feeling? Reckon a couple more hours or getting everything in my head will be enough. The article is far more pleasant this year and I'm feeling more confident than last summer.

So... how's everyone (or anyone for that matter) feeling? Reckon a couple more hours or getting everything in my head will be enough. The article is far more pleasant this year and I'm feeling more confident than last summer.

I'm feeling reasonably confident about the core areas... not so confident about the article. Any particular areas from past topics you'd recommend looking over? I'm pretty familiar with Topics 5-8 but anything specific from AS level?

Grade boundaries are reassuring for this exam as they were for Unit 4, with 62% gaining an A* grade and 57% an A, last June.

I think proteins and enzymes etc from Unit 1 could be used in the article, as well as more complicated stuff from protein synthesis. I'm horribly unfamiliar with Unit 2 and 4 so I might look over that now, I'm hoping a lot of it will spring to mind really. I've been revising Unit 5 hard and a bit of wider reading around the article.

I only actually need a D in this exam to get a B overall but I really don't want to think like that! And those are some pretty cushty grade boundaries, hopefully they'll stay like that.

I am starting to poo my pants a little bit but that's cus it's quite important

I'm in the same boat with the whole need to get the grade... I need between a low B and a high A* depending on how my Unit 4 went. I'd be feeling more confident if I could actually Tell how my Unit 4 went. But, meh!

Thanks for the tips, I'm holding out for a question on protein synthesis tbh.. or if they could somehow ask about virus transcription factors and link that into the general way viruses invade their host... that'd be great!

Thanks for the topic tips.

Ah fair enough! That's the trouble with Edexcel you can never ever bloody tell haha.

I was thinking about the viruses as well cus of Retroposition etc. Do you think you could remind me of how that works? I'm all textbooked-out to read from a textbook And obviously it would help you remember too

edit: I'd look out for PCR and Inflammation too. There's theNF-k B transcription factor which only has a cheeky small bit but it's involved in inflammation, so there might be something on that.

editedit: Also, regarding the transcription factor Dorsal, the article makes a massive point about there being "two other transcription factors" that it works alongside with, without actually naming them. I know that one of them is called Cactus, and the other one (although I'm pretty sure this is wrong) is called Toll. Maybe get you some extra marks if it asks about Dorsal. That's the TF that shapes the development of muscles and internal organs etc in fruit flys; its versatility is due to its relationship with the other two TFs (Cactus and maybe Toll).

Here are my mark points on it (the points which gained credit when the question has come up before):
glycoprotein on virus; binds with receptors (CD4); on surface membrane of lymphocytes; viral RNA enter lymphocyte; viral RNA used to produce viral RNA (in lymphocyte); by action of reverse transcriptase; ref. to formation of new viruses; lymphocyte destroyed when viruses (bud out of/leave cell); T Killer (cells/lymphocytes) destroy infected T Helper (cells/lymphocytes);

Words in italics gained credit if correct spelling was used.

Agreed! PCR is all good, inflammation not as up to date... think there's quite a lot of detail on it in one of the AS units?

Possible since they talk about evolution a lot and mutations they might want possible method to compare DNA of two species such as in Gel Electrophoresis?

I've been wondering about this, do they ask questions based on the article which require knowledge which would have to be obtained from outside of the syllabus or do they limit themselves to questions which Must be answerable based on past topics?

Thank you! CD4, reverse transcriptase, embarrassingly all forgotten! Hopefully that'll be in my head tomorrow.


Ummm all I was looking at for Inflammation was the stuff in Unit 4. E.g. Vasodilation to increase blood flow; increase permeability of blood vessels; more immune cells to site of infection; increased permeability means immune cells can move into infected tissue etc. I can't remember anything in AS but I could be very wrong.

Hehe, I got confused... it was Clotting in AS not inflammation.

Here's all I could see that's been in previous topics and I guess could be related to the article -

TOPIC 1
Proteins
Heart Disease - genetic aspect.

TOPIC 2
Nucleic acid, Enzymes
Example of genetic disease - Cystic Fibrosis, gene therapy, ethics..

TOPIC 3
Meiosis
Cell differentiation
Cancer

TOPIC 4
Drug development
Mutations and Natural Selection

TOPIC 5
Gene mutation, Gene families
Haemoglobin

TOPIC 6
Transcription/ Post Transcriptional Changes/ Translation
DNA identification/ PCR
Retroviruses (HIV)
Inflammation


Some are simple enough, probably known in greater depth from covering them in A2, others I guess would need more looking over.

I'm heading off now. Need to be up early to go over it all!

Good luck. Thanks for the help!