Genomic DNA from the nematode worm Caenorhabditis elegans is orga...

Question

Genomic DNA from the nematode worm Caenorhabditis elegans is organized by nucleosomes in the manner typical of eukaryotic genomes, with 145 bp encircling each nucleosome and approximately 55 bp in linker DNA. When C. elegans chromatin is carefully isolated, stripped of nonhistone proteins, and placed in an appropriate buffer, the chromatin decondenses to the 10-nm fiber structure. Suppose researchers mix a sample of 10-nm–fiber chromatin with a large amount of the enzyme DNase I that randomly cleaves DNA in regions not protected by bound protein. Next, they remove the nucleosomes, separate the DNA fragments by gel electrophoresis, and stain all the DNA fragments in the gel.

Explain the origin of DNA fragments seen in the gel.

Accepted Answer

Hi, everyone. Let's look at our next question. It says which of the following types of electrophoresis method is most commonly used to separate amino acids. Choice. A agarose gel electrophoresis choice BS T S, polyacrylamide gel, electrophoresis C capillary electrophoresis or D all of these. Well, electrophoresis can be used to separate many different molecules. Um We commonly think of it separating DNA, separating proteins can also be used to separate amino acids. And it of course involves using electrical charge to separate molecules as well as the size of the molecules. But let's keep in mind that when we're talking about amino acids, they're very small molecules compared to other things we might want to separate. Certainly compared to proteins which are polypeptides, many amino acids or DNA sequences which tend to be longer and larger than individual amino acids and that they can have a variety of charges. Whereas DNA is negatively charged proteins, you prepare for a gel to coat them with no negative charge, but amino acids can be positive negative or uncharged. So in that case, the best technique for separating amino acids is choice c capillary electrophoresis that offers the highest specificity of separation. So when you're looking at these small molecules and allows the molecules to go towards the A node or the cathode depending on their charge. So, capillary electrophoresis is the best choice to a Agarose gel electrophoresis is mainly used for separating DNA molecules. And that's why that's not our correct answer. And choice B SDS polyamide gel electrophoresis is mainly used for separating proteins. We use that because the S CS which is a detergent um sort of breaks down the protein or denatures the protein molecules. So they become linear instead of their usual uh 3d structure and also coats the protein in a negative charge that will run along a gel. But that's not useful for separating amino acids. So choice B is not correct and then obviously choice D all of these is not correct since A and B are wrong. So again, what type of electrophoresis is best for separating amino acids? Choice C capillary electrophoresis. See you in the next video.

Key Concepts

Nucleosome Structure

DNase I Activity

Gel Electrophoresis

Watch next