Alternative DNA Forms - Online Tutor, Practice Problems & Exam Prep

Alternative DNA Forms

Hi. In this video, we're going to talk about alternative DNA forms. So, there are many different forms of DNA. The one we're most commonly familiar with is called bDNA, and this is that right-handed helix that we always see. It's the most common DNA form. This occurs in humans and other organisms. This is what we see, and this is, like, the real form of DNA. But in the laboratory setting and sometimes out in nature in sort of weird, unusual situations, you can see other forms of DNA, and so the 2 most common are A and zDNA. A is a shorter, right-handed helix, and Z is actually a left-handed helix. And so, there are also other forms here, C, D, E, P, V, and A, and there are others that I'm not even mentioning here. They all are different sizes and have different structures, usually formed in high salts or weird pHs or without lots of water, etcetera, etcetera. But just know that not all DNA looks like this. Some of it looks like the aDNA form, which is shorter, kind of crunched together, or the zDNA form, which is a left-handed helix. You can see it looks different. Right? This, if you know that bDNA is a right-handed helix, kinda does actually just look backward compared to this one which is still going the same direction but is just shorter. Right? This one, it's not really like bDNA. And so, these are the 3 main types of DNA, but just know that there are these other forms out there that can form in certain, really unusual conditions like high salt or pH. So with that, let's now move on.

Which of the following types of DNA is the most common DNA form?

• A. A-DNA
• B. B-DNA
• C. C-DNA
• D. D-DNA

Which of the following types of DNA is characterized by a left-handed helix?

• A. A-DNA
• B. B-DNA
• C. C-DNA
• D. Z-DNA