Chromosome chromatin and chromatid

welcome back guys welcome to another video tutorial from somos biology and in this video lecture I'll be talking about chromosome chromatid and chromatin and DNA so what are all these things you know these names are a little bit confusing sometimes people don't understand it fully but they try to do a lot of stuff I I know very many students who don't have a clear idea of all these four things but still they want to study and they're doing their BSA's and emesis and stuff so let me review about what all those things mean now first things first chroma team let me explain that let me break it down in in fractions and explain so first thing is chromatin chromatin if I divide it in two parts it would be DNA plus protein ok now the protein we are talking about here is histone okay histone is a DNA binding protein okay and histone is not again made with one subunit is made with to four different subunits repeated twice every subunit so ultimately eight subunits and it's known as octa ma histone octamer okay and this histone octamer is taken and DNA is wrapped around this histone octamer and we all know what DNA is the blueprint of life every information is placed there and you know in eukaryotic cell we have all these things chromosome chromatin and stuff in prokaryotes however we only have DNA as the genetic material in the cytosol but in eukaryotes we have a separate room we have a complete separate room allotted for the chromosome to be placed where the DNA resides so when DNA is wrapped around histones we form chromatin and such chromatin is kind of it is it is unconscious form it's like a beads on a string like structure how it looks let me draw the structure here the DNA and chromatics DNA and this is how this order this is these are the structures let me highlight it with different color these are the histone octamers at the middle and this black thread like thing is the DNA so they are arranged like this this is known as the chromatin and chromatin is the way to organize DNA because you know there are a lot of informations in eukaryote compared to the prokaryotes klokateers only have the genes coding for proteins but in eukaryotes we have two types of gene some gene code for proteins and some don't write in the RNA that we produce in eukaryotes it carries introns and exons exams are the section of the RNA that codes for proteins while introns don't so we have a lot of junk materials so the DNA content of eukaryote is huge and the only way to place it properly in small tiny nucleus is to properly coil it and condense it so once we coil it and wrap it around histone we call it a chromatin but chromatin is not the pure condensed form it is semi condensed now chromatin is the structure of DNA how it is present throughout the time inside the cell normal cell and we cannot visualize chromatin with microscope normally it's not very easy to visualize it properly now what happens during the time of cell division this chromatin condenses farther and those further condensed form of chromatin is known as chromosome okay this chromatic will further condense because it will this beads on a string model slowly start to arrange in much complicated fashion it start arranging themselves something like this see something like this this is much condensed you see these are these are the histones again I am drawing and there are so many other proteins known as folding proteins which help this DNA to be properly anchored with each other and they form very thick structures very condensed and thick structure this is known as chromosome but we can only see that during cell division in the time of prophase and the beginning of the cell division this chromatin slowly start to condense and form chromosome and chromosome is easy to be stained and we can visualize this chromosome under a light microscope so whatever thing you see during the cell division plates it is formed during the process of cell division we can see that in under the microscope now now we have a idea of chromatin and chromosome because in cell division we need to replicate the genetic content that is DNA we want to replicate DNA so once we replicate the DNA we made two different copies of the DNA because we need to spread two different copies in to daughter organ to daughter cells so that the cell received the same content that is the idea of mitotic cell division because in mitosis identical cells will generate from the mother cell and the only way to do this is replicate the DNA spread it to the daughter cell so what happens here they made this condense so that it will be easy to be replicated and slowly separate them okay now in this case during the replication let's say this DNA is now replicated in that form after the replication what happens I am telling at the very beginning without the replication we have the chromosome and chromosome is condensed this is the structure let's say of the chromosome tendons format we see in the prophase now it is replicated after the replication two copies are generated two copies of the chromosomes will be generated but those copies will remain attached in the centromere they'll remain at us in the centromere region they are not separated after the replication okay the separation will take place in anaphase remember in anaphase microtubules will be attached from both the ends and they will separate the two identical chromosomes now at that point when the chromosome is already replicated all of this two identical chromosomes known as chromatid then it will be known as chromatid that is the idea so chromatid is nothing but the dot sister chromosomes that represent there okay now the chromatids here as they are linked with each other and they're replicated form of self we known as a sister chromatids okay now there are other chromatic pairs as well so let's say let me take another pair say such as we have another pair of chromatid here so if you take this chromatid here and this chromatic here and these two chromatids are not originated from the same type so they are non sister chromatid but when two chromatids are linked with each other and originally from one specific type of DNA replication x' known as sister chromatids so chromatid is nothing but chromosomes but when it is replicated then you will call it as a chromatic okay now remember during the process of replication or even in process of transcription if required in different stages we need to access this DNA now one question should come in your mind is that this DNA is tightly wrapped around histones so how could we get some part of the DNA sequence for the transcription and production of proteins now answer for that is chromatin remodeling it's not necessarily that Dean is always wrapped around Chrome atoms there it Dean is always wrapped around histones there the idea is when we require let's say a gene is present here this is the area of the gene we want to express in that condition but it is properly tied and wrapped around histone we can remodel this chromatin complex what we can simply unwind the DNA from histone here so we get the access to that hey let us say this is the unwinding and this is the idea of the gene that we want to transcribe we have the access to that area where the histone will be removed then we use that area to transcribe and produce mRNA this is known as chromatin remodeling there are other things known as chromatin modifications so many different types of histone modifications that will allow ultimately to change and accessibility of the DNA and that actually controls the expression of genes in eukaryotic cells so in eukaryotic cells there are several different room or rounds of expression control of expression this is one type of primary level controls that is always present there okay so that in a sense are about chromatin chromatid DNA and chromosome I hope you understand now and your confusion is gone so if you like this video please hit the like button share 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Channel: Shomu's Biology

Views: 561,299

Rating: 4.8830047 out of 5

Keywords: suman bhattacharjee, shomus biology, Chromosome chromatin and chromatid, chromosome and chromatid, chromatin, chromosome, chromatid, chromatin and chromatid, dna and protein, nucleosome, cell biology, chromonema, histone protein, histone octamer

Id: 22LC5ZUyvyE

Length: 10min 21sec (621 seconds)

Published: Mon May 02 2016