DNA gel electrophoresis?

Question

The primary reason that DNA gel electrophoresis is usually undertaken using an agarose gel and not an acrylamide based gel as in protein electrophoresis is:
(a) DNA is always negatively charged while proteins are not
(b) that using an agarose gel makes it easy to distinguish DNA from proteins
(c) that higher voltage must be used for DNA electrophoresis
(d) that detection and visualization of DNA bands is easier on agarose based gels
(e) due to the larger size of DNA compared to proteins

which is the correct answer. i need them for my exam,plx

Answer 1

It is E. For small oligonucleotides it is better to use polyacrylamide. On agarose gels you will get bigger gaps for small differences in size than on polyacrylamide.

When you do SDS-PAGE, you use SDS which makes your proteins negatively charged. Therefore it is not A.
You can use ethidium bromide to stain DNA and it makes no difference whether you use it on polyacrylamide or agarose; it i snot B.
I use even 200V for proteins but you cannot use these voltage with agarose gels because they would melt; it cannot be C.
You can use the same method for both acrylamide and agarose to visualize DNA and you can visualize proteins in the gel using special stainings like Comassie or Sypro Ruby or Silver staining; it is not D

Answer 2

I don't think that it's A, since protein gels are often SDS-PAGE. The protein is coated in SDS, which overwhelms any positive charge and makes the whole protein very negatively charged, then it is run on an acrylamide gel.

I also wouldn't say B, because you will stain the gel, most likely with Ethidium Bromide, which has no effect on proteins, and would not make them visible.

I woulnd't say C. It's been a while since I've run an acrylamide gel, but I don't think the voltage was much higher than an agarose gel. Besides, the whole gel apparatus heats up at high voltages, and I think that's more a function of the running buffer that's used.

It might not be E, since many DNA fragments run on a gel are very small, moreso than a protein.

By process of elimination, I'd say D. It also seems right, since protein gels are usually blotted to a nitrocellulose membrane for staining, rather than staining directly on the gel.

There are a lot of "I think" and "maybe" statements in my answer, but I don't want to be completely responsible if you lose points for this answer :P

Answer 3

I don't know if this is a good answer but you said any help is appreciated. I'll just give you a brief summation of what gel electrophoresis is used for. In gel electrophoresis you can use this electric field to separate proteins or DNA based on the size and charge of the molecule. The process works because when molecules are are placed in an electric field the charges on the molecule are attracted to the opposite charged electrode. With DNA electrophoresis you are only separating the molecules by size because the charge on each DNA molecule is the same. To separate the molecules by size the gel ( usually agarose) functions as a matrix (or obstruction) that allows small molecules to pass through quickly and large molecules to pass through slowly. So pretty much large DNA fragments pass through slowly and small ones pass through quickly. Now for an experiment you can use the different DNA segments and try and differentiate the DNA sequences based on a specific trait. It really depends on how much time you have. If I were you I would look up restriction enzymes and how they help identify traits. By the way if you alter the DNA concentration you increase or decrease the number of base pairs. Now if you fragment the DNA you are not altering the concentration of DNA because the number of base pairs is the same. I know I'm being a smart *ss but it best to be as knowledgeable as you can for the science fair. Good Luck.

Answer 4

(a), and its plz, what is phlix???