Gel electrophoresis | Biomolecules | MCAT | Khan Academy

[@ankp2407]

Just a quick note, ethidium bromide (EtBr) is usually added into the gel rather then into the DNA precisely because it binds with the DNA causing mutations and other carcinogenic effects. A loading dye (depicted by your colored DNA wells) is added into the DNA samples before inserting the DNA samples into the well. The loading dye usually consists of two tracking dyes (xylene cyanol and bromophenol blue) and glycerol. The glycerol is denser then the buffer solution and therefore allows your samples to sink into the well. Hope this helps!

[@lucaslopez2091]

how is it carcinogenic?

[@Haru-iu8bm]

Thanks for the tip

[@s_t1959]

@@lucaslopez2091 ethidium bromide enters in between base pairs in DNA and stretches the DNA and due to the stretched parts when DNA is being replicated DNA polymerase can add extra nucleotides (to the newly synthesizing strand), so what happens is when the gene is being transcribed ( if that occurred in a area which has a gene) a frame shift mutation occurs because there’re nucleotides which were not there in The original sequence , so due the mutation cancers can happen there’s a risk that’s why it’s carcinogenic, hope you got it this is how I was taught

[@lucaslopez2091]

@@s_t1959 Yeah, I got it. Thanks.

[@GirlyGirlDiazg]

dude you rockkkkk!!! first time i finish a khan video feeling happy

[@mostirreverent]

migration can also occur in just buffer, but a gel is used, so that when the electricity is turned off, the molecules stay where they stopped. The gel also acts like a sieve, so it helps to restrict migration by size. Also, DNA is by size due to charge, while proteins would not necessarily be by size since different amino acids in proteins can have different charges so you could have two different molecule sizes with the same charge.

[@GabeHable]

Usually they do an SDS-PAGE with proteins in order to the migration a consequence for the size. They mix the protein with sodium dodecyl sulfate, this substance broke the non covalent interactions of the protein and attaches to the side chains of the aminoacids in a ratio 1:2. That gives the molecule a total negative charge. So the bigger the protein more charges it will have, though it increases the fricton by a bigger proporcion, that's why the bigger the proteins are more slowly they will migrate.

[@4dxl]

Thank you

[@sararodriguesdemiranda4835]

your videos are the sole reason why i didnt fail my exams, thank you 🙏🏻

[@mazitazana1975]

Thanks for the good explanation! But, I still don't get properly what kind of information we gained or, how we interpret the information... my question is: what kind of DNA fragments do we look at? Did we have to replicate one specific sequence via PCR before? or did we use a nuclease to cut specific sequences, (which we also had to replicate to look at them I guess) and now we want to verify if they have a specific characteristic or not?... because if the fragments were randomly cut the information wouldn't serve much, would it?

[@denzellnigel8372]

Lol

[@marthedoc475]

they add RESTRICTION ENZYMES to the DNA solutions before loading them into the wells of this GEP-machine. These enzymes cut DNA strands up in tiny pieces (specific DNA bases) and are very helpful for the easier movement of DNA through the gel. At the end we can analyse the bands (DNA fragments) for example through comparing them with the bands of another DNA solution that was put in another well of the GEP-machine and maybe search for relationships btw them and so on.

[@blmg1006]

Too helpful, thanks We hope that if khan academy focus on the medical laboratory sciences & techniques..

[@maram5102]

Thank you for making an explanation for every detail. Thank you because you make science is an enjoyable subject . Thank you because you put hope on students for whenever the subject is hard ,it’s not hard enough and we can succeed and pass it .. this channel helped me for more than 4 years and thank you is never enough NEVER .

[@angussebire7976]

What is the linear relationship between log(nucleic acid) and migration distance?

[@kalukaluigwe9752]

This is a good lecture. Keep it up on other class lectures like Molecular Docking study.

[@vinaykumardaivajna2470]

Only video explained correctly.khan academy rocks again..thank you

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[@magicthegatherer6903]

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[@jayavels3373]

Good presentations

[@catchersalazar705]

Such a well drawn diagram

[@doddypal9584]

If intercalating agents are used and they bind small DNAs together, isn't it same if fewer large DNAs are bound together by the intercalating agent?

[@sciencenerd7639]

Ah this brings back the memories from biochem lab

[@1DangerRose]

he guys i wanna know is this channel ( khanacademymedicine) belongs to KHANACADEMY ? cuz i watched a lesson there and the information was wrong!! so please let me know if it belongs to you or not because i don't trust their information.

[@KoreanAwesomeness8D]

What was wrong ?

[@tonybaston3419]

Is the movement linear? For example, if you had a sample that went directly between the 1000 and 500 mark from the DNA ladder, would you be able to say it has 750 base pairs, or would it be some other amount in that range?

[@kyrality6571]

It's a Iog based scaIe!

[@sanat1102]

Can a charged dye be used to enhance movement of DNA fragments?

[@heshammostafa9984]

Very helpful thanks

[@AmanKumar-yu5jb]

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[@mohamadsaifullahbinsulaima546]

i like the way he present..help me alot

[@makemelotsotetsi8047]

Exciting. Thank YOU

[@dorianl.210]

very nice presentation

[@nyawirawaithaka4993]

Thank you!

[@sidrahassan857]

Good work

[@matthewyoungsoonam]

Easy

[@barracudahd4978]

first.

[@shaikhaalnuaimi9193]

wow

[@leoz4343]

Thx!