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

does anyone have a link to some past papers (the only one i have is Jan 2011) or a specimen? they are all secure download only on the edexcel website

Covers the whole chapter.

If it's worth five marks I would just ignore the stem cell bit.
If I got this question I'd talk about epo is a protein which binds to a receptor on a particular cell which causes the activation of a second messenger causing a kinase protein cascade. Which acts as a transcription factor to switch on a gene which causes the structure of RNA to be different which changes the structure of proteins which causes more blood cells to be created.

Pretty much what it states in the book and the examiner's mark schemes are actually massive for alternative answers, markschemes we get are just condensed I believe . (also stem cells can be found in the bone marrow so maybe that's what it's talking about)

it inhabits repolarisation of the heart which means cardiac and stroke volume falls.muscles do not receive enought bloood

This is a good question, if we think about what the QT part of the electrocardiogram stands for we can sort this question out.

The 3 main part of an ECG are as follows:

P wave - Time taken for atrial systole
QRS complex - Time taken for ventricular systole
T wave - Time taken for the repolarisation of the ventricles during diastole

So the long QT must mean that the time taken for the QRS complex and T wave to happen takes longer. Therefore, we normally say that Long QT increases the time taken for repolarisation.

This may lead to palpations of the heart, fainting or sudden death.

Hope that helped you

the bone marrow cells are the haemopoietic STEM CELLS... which epo causes to differentiate INTO reb blood cells.... it may activate and switch certain transcription factors that then go on and activate genes... a good example is the gene coding for the enzyme that produces Haemoglobin

I think what's confusing me is the actual method by which EPO, IGF-1 and other recombinant bacteria are inserted into the body or used to produce proteins/hormones, if that makes sense.
I understand the biology behind how they work such as EPO being a lipid hormone and binding to stems cells in bone marrow producing more RBC its just how is it inserted into the body

what are haemopoietic stem cells?

Recombinant Bacteria are not inserted into body, ... they produce synthetic recombinant Human Epo which humans inject into themselves

Why does there are more sarcoplasmic reticulum in fast twitch fibers?

Why does there are more sarcoplasmic reticulum in fast twitch fibers?

So using recombinant bacteria is simply a way of mass producing proteins/hormones which are then inserted into the body via viruses? or can they just be normal injections?

I swear to god i've hit the wall. maybe a power nap is needed.

thank you

sorry if its a stupid question, but what is a "kinase protein cascade"? I've never heard of it. Also, how have you been revising for the article?

I would say that in fast twitch fibres there is more movement and at a quicker rate than in slow twitch muscle. This means that there would be more muscle contractions, therefore, the sliding filament theory occurs more times per second in the fast twitch muscle.

For more muscle contraction to occur there must be more Ca2+ ions released from the sarcoplasmic reticulum, in order to shift the troponin and tropomyosin from the myosin binding site on the actin filament. One way of doing this would be to increase the sacrcoplasmic reticulum so more Ca2+ can be released at per second.

Hope this makes sense.
This is all I could think of.

ermmm

think of insulin from gcses

Recombinant dna is used to mass produce proteins or hromones like insulin and epo... which are then injected into blood directly

this sucks for diabetics and aneamics .... it means they have to inject themselves everyday

why not use a viral vector to deliver the gene to the cells to make the protein in the body automatically.... thats what gene therapy does... think back to cystic fibrosis

I haven't started "learning" anything yet ... except for respiration and the homeostasis chapter ...

Do you think I would be able to do good in the example just by learning what is in the specification?