In prophase of mitosis, each DNA strand condenses down to become much shorter and thicker by winding up much more tightly, in a process called supercoiling. This allows each strand of DNA to become visible, which is when it resembles the sausage shape that most would associate as being a chromosome. In prophase, each chromosome is visible as an X shaped sausage as the DNA has just been replicated.
The two halves of the X are identical to each other as one is a copy of the other. Sister chromatids are the branches of one chromosome. Chromatin VS. Chromosome: an overview Chromatin, chromosomes and chromatids: in depth. What is the difference between chromatin, chromosomes, and sister chromatids? Mary Ann. Jan 16, Because the newly divided cell should have the complete set of chromosomes. To achieve this each chromosome duplicates itself and they will be attached at the point of centromere which looks like shown in figure c.
We sometimes refer to it as sister chromatids when we talk about recombination right!! So the chromatid is nothing but duplicated chromosome which has not yet separated. Now when cell will divide each of the new cell will get one copy of chromatid and this chromatid will act as chromosome itself in that new cell.
The same chromatid would decondenses into a chromatin strand. Time for a true story now. Current timeTotal duration Google Classroom Facebook Twitter. Video transcript Before I dive into the mechanics of how cells divide, I think it could be useful to talk a little bit about a lot of the vocabulary that surrounds DNA. There's a lot of words and some of them kind of sound like each other, but they can be very confusing. So the first few I'd like to talk about is just about how DNA either generates more DNA, makes copies of itself, or how it essentially makes proteins, and we've talked about this in the DNA video.
Just some small section. It keeps going. And, of course, it's a double helix. It has its corresponding bases. Let me do that in this color. And then, of course, it just keeps going on in that direction. So there's a couple of different processes that this DNA has to do. One is when you're just dealing with your body cells and you need to make more versions of your skin cells, your DNA has to copy itself, and this process is called replication. You're replicating the DNA.
So let me do replication. So how can this DNA copy itself? And this is one of the beautiful things about how DNA is structured. So I'm doing a gross oversimplification, but the idea is these two strands separate, and it doesn't happen on its own. It's facilitated by a bunch of proteins and enzymes, but I'll talk about the details of the microbiology in a future video.
So these guys separate from each other. Let me put it up here. They separate from each other. Let me take the other guy. Too big. That guy looks something like that. They separate from each other, and then once they've separated from each other, what could happen?
Let me delete some of that stuff over here. Delete that stuff right there. So you have this double helix. They were all connected. They're base pairs. Now, they separate from each other. Now once they separate, what can each of these do?
They can now become the template for each other. If this guy is sitting by himself, now all of a sudden, a thymine base might come and join right here, so these nucleotides will start lining up. So you'll have a thymine and a cytosine, and then an adenine, adenine, guanine, guanine, and it'll keep happening. And then on this other part, this other green strand that was formerly attached to this blue strand, the same thing will happen. You have an adenine, a guanine, thymine, thymine, cytosine, cytosine.
So what just happened? By separating and then just attracting their complementary bases, we just duplicated this molecule, right? We'll do the microbiology of it in the future, but this is just to get the idea.
This is how the DNA makes copies of itself. And especially when we talk about mitosis and meiosis, I might say, oh, this is the stage where the replication has occurred. Now, the other thing that you'll hear a lot, and I talked about this in the DNA video, is transcription. In the DNA video, I didn't focus much on how does DNA duplicate itself, but one of the beautiful things about this double helix design is it really is that easy to duplicate itself.
You just split the two strips, the two helices, and then they essentially become a template for the other one, and then you have a duplicate. Now, transcription is what needs to occur for this DNA eventually to turn into proteins, but transcription is the intermediate step.
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