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AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011

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Original post by Thisisj


haha that's awesome :biggrin:
Reply 2081
Avatar for nosta
nosta
Original post by kingsmod1
i dont undesrtand the point of the sanger method by adding terminator nulceotides, i know it stops process but what is the point????

Many thanks :P


It allows you to find the base sequence of a fragment of DNA. As a complementary stop codon will bind to a base on each DNA fragment. It will produce strands of varying lengths. As there are 4 different tubes each with a different stop nucleotide you are able to identify what each base is in the sequence by what complementary terminator binded to which part of the base sequence. (you will already know the total length of the DNA fragment)

pretty bad explanation by myself, but hopefully it helped a little
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Avatar for Thisisj
Thisisj
Original post by Cyanohydrin
haha that's awesome :biggrin:


:smile:
Original post by Tericon
Thank you for helping me with this btw :smile: Big weight off my mind :smile:


No problemo, I'm glad I could help. I'm off now though, so fingers crossed we have the most charming paper in the history of ever. Also, with a nice, open-ended essay question like 'what are the uses of proteins' or 'I'm so hungover right now, just draw a smiley face and you'll get full marks'. :biggrin:
Original post by nosta
It allows you to find the base sequence of a fragment of DNA. As a complementary stop codon will bind to a base on each DNA fragment. It will produce strands of varying lengths. As there are 4 different tubes each with a different stop nucleotide you are able to identify what each base is in the sequence by what complementary terminator binded to which part of the base sequence. (you will already know the total length of the DNA fragment)

pretty bad explanation by myself, but hopefully it helped a little


no that's a good explanation :smile: cleared a few things up for me...
Are polysaccharides and carbohydrates basically the same thing?
why do nerve impulses propogate one way....?

- refractory period as a result of hyperpolarisation?? is that the answer?
Why isnt this exam in the afternoon :mad:
Reply 2088
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Jasx
Original post by Cravez
the latter.


thanks, i realised how stupid it sounded after i asked it :| aha
Reply 2089
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NRican
Original post by appleschnapps
http://www.thestudentroom.co.uk/showthread.php?p=32365141&highlight=

Remember, if you have more than one radioactive fragments, it is including partial digests so the first cut in the sequence will be the smallest radioactive fragment. Then, because the next radioactive fragment is at 4kb, it must be 3+1. :smile:


Thanks a bunch :smile:
What about 9bii Explain the presence of the three additional fragments in the partial digestion lane.

Sorry it may sound really stupid but only did C16 yesterday :s-smilie:

Original post by strawberry_cake
Why isnt this exam in the afternoon :mad:


So we can revise for Chem5 in the afternoon :redface: :mad:
Original post by flowerscat
From the bottom up-
A band corresponding to primer only - this is discounted (and you won't be shown this band in the exams)
The first band of your sequence will correspond to (Primer)+(one base)
The second of your sequence will correspond to (Primer)+(two bases)
The third band of your sequence will correspond to (Primer)+(three bases)

is that any more clearer?


So basically, in DNA sequencing we're finding out the DNA fragment from the primer, therefore, we don't actually find the sequence of the whole DNA fragment - unless we know the nucleotide bases in the primer?
Original post by Cyanohydrin
why do nerve impulses propogate one way....?

- refractory period as a result of hyperpolarisation?? is that the answer?


Yes that, and im not sure but you could say that in synapses sodium gates are only located on the post synaptic membrane and not the presynaptic membrane therefore ensuring it travels in one direction.
Reply 2092
Avatar for atofu
atofu
7
Does anyone have any predictions?
So far i'm guessing
- Muscle contractions
- synapse question (could be with panician cells or cone/rod cells)
- gene therapy + ethics type question
- Negative feedback - thermoregulation

as for the essays i think one could be to do with genetics (possible variation or something)
Reply 2093
Avatar for NRican
NRican
You know when reading Gel E it says from the bottom up - do you read the smallest eg. the one that's furthest first and so on?


Original post by atofu
Does anyone have any predictions?
So far i'm guessing
- Muscle contractions
- synapse question (could be with panician cells or cone/rod cells)
- gene therapy + ethics type question
- Negative feedback - thermoregulation

as for the essays i think one could be to do with genetics (possible variation or something)


I think Gel E and Restriction mapping will deffo come up.

And in the essay ATP, Cell Structure, transfer of stuff across cells or ecosystems.
(edited 12 years ago)
Reply 2094
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bobsaeed
Original post by addvic

Original post by addvic
all hormones do, that is how they work


not oestrogen.... because thats lipid soluble
Reply 2095
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Phalange
1) Chemoreceptors are found in medulla, aorta and cartoid artery. Say the chemoreceptor in aorta detected high CO2, low O2 and low pH. It would send impulse via sensory neurone to medulla to decide what to do. What would happen if the medulla detected the high CO2 etc? Would it "skip" the sensory neurone part or...?

2) IAA inhibits growth in roots but stimulates growth in tips right? Wouldn't gravity cause IAA to accumulate at the tip of the root causing it to stop growing downwards? Unless the root growing region is NOT the tip? :|

Thanks if anyone can help! Quote me
Original post by Cyanohydrin
why do nerve impulses propogate one way....?

- refractory period as a result of hyperpolarisation?? is that the answer?


Because of the refactory period as an action potential can only pass from and active to a resting region.
Also, in terms of synapse, the neurotransmitter Acetycholine is only synthesised in the presynaptic neurone which means that the only direction for the wave of depolarisation is to to the post synaptic neurone. Receptor sites are also only in the post-synaptic neurone as well.

Really bad explanation I know:biggrin:
Synoptic bit worrying me a bit..dont want to get bogged down in stuff like unit 1 bio
Original post by NRican


So we can revise for Chem5 in the afternoon :redface: :mad:


I wouldn't have minded a couple extra hours to revise :redface: I hope the exam goes well or it'll make me really demotivated for chem :frown:
Original post by Phalange
1) Chemoreceptors are found in medulla, aorta and cartoid artery. Say the chemoreceptor in aorta detected high CO2, low O2 and low pH. It would send impulse via sensory neurone to medulla to decide what to do. What would happen if the medulla detected the high CO2 etc? Would it "skip" the sensory neurone part or...?


chemoreceptors detect pH - that is all (as far as I know)

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