Biology help

How much did you pay for medic school? Like, do you even have to pay or anything?

What should i do when its like that in an exam like this?

Hey, I know that's an awkward question but how do you delete a thread in here?

what GCSE grades did you get and any tips for people doing them now?

Hey everyone, I am a medical student who doesn't really have time to do any proper, paid tutoring, however I am interested in teaching and helping people in general. I have tutored before, so if anyone is stuck on any GCSE/AS/A2 biology (or chemistry too for that matter) then feel free to ask and I'll help. Also if anyone has any questions about applying to medical school then I can help there too as I was in that position only last year, so it's fresh in my mind. I got 4 A's at AS and 3 A*s at A2 (bio, chem, maths, all above 95%)

dude your grades are unreal

Thanks, sadly it comes at the cost of being absolutely awful with women :P But atleast I can label the components of a vertebra and describe how the greater and lesser omenta are formed! ..

But yh, work hard and you'll get good grades and no girls haha

ahahaha good point. who needs women when you've got bio!
i'm actually a girl.. lol and despite never having been in a relationship my grades are average I would say lol. ABB in AS (after resitting btw)

Hmm, I cannot agree with you on that "who needs women when you've got bio" comment aha, biology gets very boring very quickly! And they're good! Just don't do what I did, which was study too much, because it's not attractive it seems haha. I've had a fair few women like me, but they were all put off because I always had my nose in a textbook, and it's pretty depressing :P

It was actually a joke. It something I tell myself when I feel like a loner lol.
You still have time though. You can let loose for a while and throw that book away.
For me, it's not even about over reading. It's because I don't think i'm very interesting, that's why I'd rather sleep in my room haha

haha I'm glad, and nah, I'm sure you're not uninteresting, but anyway, I better get back to revising, so much anatomy to learn

Hi, I was just wondering whether you could help me with restriction mapping/DNA sequences ^.^

How exactly can you work out the sequence of DNA by using restriction mapping (of long DNA fragments)? Im sure you'd use restriction endonucleases to cut up the DNA and then use DNA sequencing and Gel electrophoresis to work out the actual DNA sequence of each smaller fragment, but how would you then know the full sequence, because your original DNA is now cut up into smaller fragments so how would you know where to place the DNA fragments into their respective places?

Thank you! :-)



Posted from TSR Mobile

Hi, I was just wondering whether you could help me with restriction mapping/DNA sequences ^.^

How exactly can you work out the sequence of DNA by using restriction mapping (of long DNA fragments)? Im sure you'd use restriction endonucleases to cut up the DNA and then use DNA sequencing and Gel electrophoresis to work out the actual DNA sequence of each smaller fragment, but how would you then know the full sequence, because your original DNA is now cut up into smaller fragments so how would you know where to place the DNA fragments into their respective places?

Thank you! :-)



Posted from TSR Mobile

Yh this is tricky, so the point of restriction mapping is to sequence DNA fragments rather than a whole length of DNA, because it's easier to sequence shorter pieces of DNA. As you've correctly pointed out, how do you know the order in which the sequence is? Well restriction mapping involves digesting DNA with individual restriction endonucleases, and then combinations of restriction endonucleases to allow you to piece together the DNA kind of like a jigsaw. I'll try my best to illustrate it with an example:

So let's say you have a 10kb (kilobase) length of DNA and you digest it with EcoRI and BamHI, and you end up with a 2kb, 3kb and 5kb fragment. What you obviously want to know is whether the order is 2, 3, 5 or 2, 5, 3 or 3, 5, 2 or 5, 3, 2 (the reverse orders do matter because 5, 3, 2 will not just be the reverse of 2, 3, 5). So this is where restriction mapping comes into it, if you digest with just EcoRI, let's say you get two 5kb fragments and if you digest with just BamHI, you get a 3kb fragment and a 7kb fragment. If you separate these out onto a gel electrophoresis, you'll see that EcoRI cuts the DNA straight down the middle, and then BamHI cuts on of the 5kb fragments into a 2kb and 3 kb fragment. So the sequence has to be either 2, 3, 5 or 5, 3, 2. The trick is to work out which way around it goes, well what happens is you radioactively label the first bit of your original DNA sequence, in this case let's assume that it's the 2kb fragment, this 2kb fragment will be the only radioactive one on the gel electrophoresis, and therefore it will be the first fragment, so the fragment order is 2, 3, 5.

Now, if you're like me, and you're questioning why 5, 3, 2 isn't just the reverse of 2, 3, 5, then let me just show you why:

Imagine these are the fragments

5'-AT-3'
3'-TA-5'

5'-GCA-3'
3'-CGT-5'

5'-ACTGA-3'
3'-TGACT-5'

2, 3, 5 will be:
5'-ATGCAACTGA-3'
3'-TACGTTGACT-5'

and 5, 3, 2 will be:
5'-ACTGAGCAAT-3'
3'-TGACTCGTTA-5'

clearly different.

^ You literally can't go wrong with that information, restriction mapping didn't come up in my exam, and as far as I know, it rarely does, but if you get your head around what I just said, then you should be able to do any restriction mapping question, I hope

Eden Hazaaaaaaaarrddd!