7 Difference Between Chromosome and Chromatid | angelfirenm.info
A chromosome is two sister chromatids joined at the centromere 3. In mitosis the chromosome splits Related Questions (More Answers Below). Difference between homologous chromosome and sister chromatids? 2, Views · What is the. Which statement is correct concerning the relationship between chromosomes and genes, chromatin, or sister chromatids? angelfirenm.infotin is a length of DNA in a. chromosomes are the condensed and replicated form of DNA. The two identical halves of the chromosomes are sister chromatids. Before.
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.
- What is the difference between chromatids and centromeres?
- How are centromeres and chromatids related?
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.
And then that mRNA leaves the nucleus of the cell and goes out to the ribosomes, and I'll talk about that in a second. So we can do the same thing. So this guy, once again during transcription, will also split apart. So that was one split there and then the other split is right there. And actually, maybe it makes more sense just to do one-half of it, so let me delete that.
Let's say that we're just going to transcribe the green side right here.
What is the Difference Between Chromosome and Chromatid?
Let me erase all this stuff right-- nope, wrong color. Let me erase this stuff right here. Now, what happens is instead of having deoxyribonucleic acid nucleotides pair up with this DNA strand, you have ribonucleic acid, or RNA pair up with this. And I'll do RNA in magneta. So the RNA will pair up with it. And so thymine on the DNA side will pair up with adenine.
Guanine, now, when we talk about RNA, instead of thymine, we have uracil, uracil, cytosine, cytosine, and it just keeps going. That mRNA separates, and it leaves the nucleus. It leaves the nucleus, and then you have translation. The transfer RNA were kind of the trucks that drove up the amino acids to the mRNA, and this all occurs inside these parts of the cell called the ribosome. But the translation is essentially going from the mRNA to the proteins, and we saw how that happened.
You have this guy-- let me make a copy here. Let me actually copy the whole thing. This guy separates, leaves the nucleus, and then you had those little tRNA trucks that essentially drive up. So maybe I have some tRNA. Let's see, adenine, adenine, guanine, and guanine. A codon has three base pairs, and attached to it, it has some amino acid.
And then you have some other piece of tRNA. Let's say it's a uracil, cytosine, adenine. And attached to that, it has a different amino acid. Then the amino acids attach to each other, and then they form this long chain of amino acids, which is a protein, and the proteins form these weird and complicated shapes.
So just to kind of make sure you understand, so if we start with DNA, and we're essentially making copies of DNA, this is replication. You are transcribing the information from one form to another: Now, when the mRNA leaves the nucleus of the cell, and I've talked-- well, let me just draw a cell just to hit the point home, if this is a whole cell, and we'll do the structure of a cell in the future. If that's the whole cell, the nucleus is the center.
That's where all the DNA is sitting in there, and all of the replication and the transcription occurs in here, but then the mRNA leaves the cell, and then inside the ribosomes, which we'll talk about more in the future, you have translation occur and the proteins get formed. So mRNA to protein is translation. You're translating from the genetic code, so to speak, to the protein code.
So this is translation. So these are just good words to make sure you get clear and make sure you're using the right word when you're talking about the different processes. Now, the other part of the vocabulary of DNA, which, when I first learned it, I found tremendously confusing, are the words chromosome.
I'll write them down here because you can already appreciate how confusing they are: So a chromosome, we already talked about.
You can have DNA. You can have a strand of DNA.
Chromosomes (article) | Khan Academy
That's a double helix. This strand, if I were to zoom in, is actually two different helices, and, of course, they have their base pairs joined up.
I'll just draw some base pairs joined up like that. So I want to be clear, when I draw this little green line here, it's actually a double helix. Now, that double helix gets wrapped around proteins that are called histones. So let's say it gets wrapped like there, and it gets wrapped around like that, and it gets wrapped around like that, and you have here these things called histones, which are these proteins.
Now, this structure, when you talk about the DNA in combination with the proteins that kind of give it structure and then these proteins are actually wrapped around more and more, and eventually, depending on what stage we are in the cell's life, you have different structures. But when you talk about the nucleic acid, which is the DNA, and you combine that with the proteins, you're talking about the chromatin. And the idea, chromatin was first used-- because when people look at a cell, every time I've drawn these cell nucleuses so far, I've drawn these very well defined-- I'll use the word.
So let's say this is a cell's nucleus. I've been drawing very well-defined structures here. So that's one, and then this could be another one, maybe it's shorter, and then it has its homologous chromosome. So I've been drawing these chromosomes, right? And each of these chromosomes I did in the last video are essentially these long structures of DNA, long chains of DNA kind of wrapped tightly around each other.
So when I drew it like that, if we zoomed in, you'd see one strand and it's really just wrapped around itself like this.
And then its homologous chromosome-- and remember, in the variation video, I talked about the homologous chromosome that essentially codes for the same genes but has a different version. If the blue came from the dad, the red came from the mom, but it's coding for essentially the same genes.
So when we talk about this one chain, let's say this one chain that I got from my dad of DNA in this structure, we refer to that as a chromosome. Now, if we refer generally-- and I want to be clear here. DNA only takes this shape at certain stages of its life when it's actually replicating itself-- not when it's replicating. Before the cell can divide, DNA takes this very well-defined shape.
Most of the cell's life, when the DNA is actually doing its work, when it's actually creating proteins or proteins are being essentially transcribed and translated from the DNA, the DNA isn't all bundled up like this. Because if it was bundled up like, it would be very hard for the replication and the transcription machinery to get onto the DNA and make the proteins and do whatever else. Normally, DNA-- let me draw that same nucleus. Normally, you can't even see it with a normal light microscope.
It's so thin that the DNA strand is just completely separated around the cell. I'm drawing it here so you can try to-- maybe the other one is like this, right? And then you have that shorter strand that's like this. And so you can't even see it. It's not in this well-defined structure.
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This is the way it normally is. And they have the other short strand that's like that. So you would just see this kind of big mess of a combination of DNA and proteins, and this is what people essentially refer to as chromatin. So the words can be very ambiguous and very confusing, but the general usage is when you're talking about the well-defined one chain of DNA in this kind of well-defined structure, that is a chromosome.
Chromatin can either refer to kind of the structure of the chromosome, the combination of the DNA and the proteins that give the structure, or it can refer to this whole mess of multiple chromosomes of which you have all of this DNA from multiple chromosomes and all the proteins all jumbled together.
So I just want to make that clear. Now, then the next word is, well, what is this chromatid thing? What is this chromatid thing? In this state, the DNA can be accessed relatively easily by cellular machinery such as proteins that read and copy DNAwhich is important in allowing the cell to grow and function.
Condensation takes place when the cell is about to divide. When chromatin condenses, you can see that eukaryotic DNA is not just one long string. Bacteria also have chromosomes, but their chromosomes are typically circular. Chromosomes Each species has its own characteristic number of chromosomes. Like many species of animals and plants, humans are diploid 2nmeaning that most of their chromosomes come in matched sets known as homologous pairs.Chromosome chromatin and chromatid
The 46 chromosomes of a human cell are organized into 23 pairs, and the two members of each pair are said to be homologues of one another with the slight exception of the X and Y chromosomes; see below. Human sperm and eggs, which have only one homologous chromosome from each pair, are said to be haploid 1n. When a sperm and egg fuse, their genetic material combines to form one complete, diploid set of chromosomes.
So, for each homologous pair of chromosomes in your genome, one of the homologues comes from your mom and the other from your dad. Image of the karyotype of a human male, with chromosomes from the mother and father false-colored purple and green, respectively.
Image modified from " Karyotype ," by the National Institutes of Health public domain. The two chromosomes in a homologous pair are very similar to one another and have the same size and shape. Most importantly, they carry the same type of genetic information: However, they don't necessarily have the same versions of genes. That's because you may have inherited two different gene versions from your mom and your dad. It's possible for a person to have two identical copies of this gene, one on each homologous chromosome—for example, you may have a double dose of the gene version for type A.
On the other hand, you may have two different gene versions on your two homologous chromosomes, such as one for type A and one for type B giving AB blood. The sex chromosomes, X and Y, determine a person's biological sex: XX specifies female and XY specifies male. These chromosomes are not true homologues and are an exception to the rule of the same genes in the same places.
Aside from small regions of similarity needed during meiosis, or sex cell production, the X and Y chromosomes are different and carry different genes. The 44 non-sex chromosomes in humans are called autosomes.
Chromosomes and cell division Image of a cell undergoing DNA replication all the chromosomes in the nucleus are copied and chromosome condensation all the chromosomes become compact. In the first image, there are four decondensed, stringy chromosomes in the nucleus of the cell.
After DNA replication, each chromosome now consists of two physically attached sister chromatids. After chromosome condensation, the chromosomes condense to form compact structures still made up of two chromatids. As a cell prepares to divide, it must make a copy of each of its chromosomes.
The two copies of a chromosome are called sister chromatids. The sister chromatids are identical to one another and are attached to each other by proteins called cohesins.
The attachment between sister chromatids is tightest at the centromere, a region of DNA that is important for their separation during later stages of cell division. As long as the sister chromatids are connected at the centromere, they are still considered to be one chromosome.
However, as soon as they are pulled apart during cell division, each is considered a separate chromosome. What happens to a chromosome as a cell prepares to divide. The chromosome consists of a single chromatid and is decondensed long and string-like. The DNA is copied. The chromosome now consists of two sister chromatids, which are connected by proteins called cohesins.
It is still made up of two sister chromatids, but they are now short and compact rather than long and stringy. They are most tightly connected at the centromere region, which is the inward-pinching "waist" of the chromosome. The chromatids are pulled apart.