gel electrophoresis

[Tim035]

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How much detail should be know about get electrophoresis?
Our teacher made us do an entire work sheet on it, and conquering chemistry devotes a couple of pages to it. But realistically its just one step in the dot point adressing describing the process used to analyse DNA.

I'm currently doing the edassit program and in their booklet they've just got a few sentences on gel electrophoresis as one of the steps in DNA analysis is this adequate?

[Survivor39]

Well, it would be good to actually know how it works. It is not just one of the step in the analysis of DNA. The point is to visualise whether DNA is present and the basis is dependent on the -ve charge of nucleic acid migrating towards the + ve terminal.

[surfing_chaos]

hahah our teachers attempted to do it... ordered a kit and all... it failed... miserably... hahaha

[Tim035]

lol yeah our electrophoresis prac failed miserably aswell..

[lala2]

Say that the components will migrate at different speeds depending on how charged and how big they are already, and this will separate them out. and yes, as Survivor said, migrate from -ve to +ve terminal.

Think of it as an electrical form of chromatography. So for the case of DNA, its components will separate out, leaving a distinct set of "bands" and if this sequence is the same between the sample DNA and that of a suspect, then you be reasonably assured that the suspect is guilty. Also, if I remember correctly, DNA can be used to determine the paternity of a child--the child's DNA should have some bands from the mother, and some from the father.

[Tim035]

Yeah.. I know how normal electrophoresis works based on isoelectric point and mass of the components being seperated its preety straight forward I think personally.
But I'm more adhering to the dot point that says:
"describe how a DNA profile is created"

Not the dot point:
"Describe the process of electrophoresis and identify the characteristics that allow it to seperate components".

[n@ttyb]

wouldnt that be the resulting bands- that are stained so to be visible ??

[SS06]

we did not undertake the gel electrophoresis practical. We did a simulation program on the net. If we were asked to write about the practical component of the dot point wat should I write???

[n@ttyb]

we did the simulation too... so maybe you just write about using restriction enzymes to make them smaller pieces and then putting them in the gel to be seperated ... and then talk about why they are seperated

maybe...

[Tim035]

yeah the electrophoresis prac has got me preety edgy personally.
Every year it seems they ask for a description of a prac in the option section and the list of pracs remaining is growing very thin with electrophoresis being one of the only major pracs left.

I think though... due to the variety and huge ways of performing the experiment they couldn't ask for results and a full like 5-7 marker on it. I think the most they could do is like a 3 mark outline.
In which case u could say u put agarose gel on a plate then used thin layer polyester to make wells at one end of the gel. Aplied two electrodes with the negative one being furthest away from the gel, placed the sample to be tested in some of the wells hit the power and let it run.

[n@ttyb]

i didnt no u had to know how to make it- like set it up. Thats a bummer.
Also im guessing their gonna ask a question based on the differences of electrophoresis and chromatography

[Survivor39]

Originally Posted by Tim035

yeah the electrophoresis prac has got me preety edgy personally.
Every year it seems they ask for a description of a prac in the option section and the list of pracs remaining is growing very thin with electrophoresis being one of the only major pracs left.

I think though... due to the variety and huge ways of performing the experiment they couldn't ask for results and a full like 5-7 marker on it. I think the most they could do is like a 3 mark outline.
In which case u could say u put agarose gel on a plate then used thin layer polyester to make wells at one end of the gel. Aplied two electrodes with the negative one being furthest away from the gel, placed the sample to be tested in some of the wells hit the power and let it run.

Don't forget you need to use a buffer to run the gel. You can just have a slab of agarose gel and put your sample into the well. You need a buffer suspension, allowing ions to run through the gel.

[Tim035]

Originally Posted by Survivor39

Don't forget you need to use a buffer to run the gel. You can just have a slab of agarose gel and put your sample into the well. You need a buffer suspension, allowing ions to run through the gel.

QFT, I sorta just rushed through it off the top of my head but yes an electrolyte solution with a suitable buffer is a must. could you just say an NaOH solution was spread evenly across the surface of the gel.

Honestly this option I think really doesn't have a lot to learn, compared to my bloody communication option in biology which is sttacckss of dam info to try and progress through. I think the main difference is this option doesn't need u to remember a heap of definite facts, its all processes and asessing the value of techniques etc which I love a lot more then trying to remember all the different parts of the eyes, larynx, ear and brain, their function and how they can be identified.

If they want to compare chromatography with electrophoresis go ahead and make it the 8 marker, I'll be jumping for joy. Must have done about 3 trial papers already with that question.

[Survivor39]

When I run gels in my lab, I use a buffer called the TBE buffer, which contains tris base, boric acid, and sodium EDTA. I think most labs use TBE buffer. And yes, you must fill your buffer so that it just cover the entire gel. And you let the thing run for 30 min and you're done! You take this gel and visualise your DNA under UV light and see the DNA bands.

[thejosiekiller]

electrophoresis is so fun at uni i remember touching the gel and forgetting the EtBr was carcinogenic washed my hands for like 30 mins