Gel electrophoresis | Biomolecules | MCAT | Khan Academy

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!

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

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 .

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

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.

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

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

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?

Exciting. Thank YOU

i like the way he present..help me alot

Such a well drawn diagram

Good presentations

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?

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

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?

very nice presentation

I love your videos.....

Very helpful thanks

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

Good work