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7. DNA and Chromosome Structure

Alternative DNA Forms



Alternative DNA Forms

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Hi in this video we're gonna talk about alternative DNA forms. So there are many different forms of D. N. A. The one we are most common with is called B. D. N. A. And this is that right handed helix that we always see the most common DNA form. This is what occurs in humans and other organisms. This is what we see. And this is like the real form of D. N. A. But in the laboratory setting and sometimes out in nature and sort of weird, unusual situations, you can see other forms of D. N. A. And so the two most common are A. And Z. D. N. A. And 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. D. N. A. And there's others that I'm not even mentioning here and they all are different sizes and they're different structures and usually they're formed in in high salts or weird ph is or without lots of water or you know, etcetera etcetera, etcetera. All these different conditions, but just know that not all DNA looks like this, some of it looks like the A. D. N. A form which is here. You can see it's shorter, it's kind of crunched together or the Z. DNA form which is here and that's a left handed helix. And you can see that looks different right like this if you know that this is a right handed, this kind of does actually just look backwards compared to this one which is still going the same direction, but it's just shorter. Right? This one is it's not really like this. And so um these are the three main types of D. N. A. But just know that there are these other forms out there that can form in certain really unusual conditions, like high salt or ph or something. So with that, let's not move on.

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


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