 So, as we have seen that prokaryotes are simple genomes in comparison the eukaryotes are relatively complicated. So, eukaryotes have larger genomes, they have tandem repeats in them and their introns are there and they which are in between the axons which are the protein coding regions within the genes. And eukaryotes have a little bit complicated genome, so in the chromosomes the DNA is grouped as heterochromatin densely packed region and eukromatin which is lightly packed region. Here is the typical eukaryotic cell, so we see it is pretty stuff as compared to the prokaryotic one. So, we have those nucleus in the middle, we have those lines or networks of channels coming out of the nucleus called as endoplasmic reticulum help in transportation. For protein senses, we have those ribosomes for energy senses, we have mitochondria, we also see cytoskeletal, so that supports the makes the structure of these cells intact and Golgi operators they are concerned with the secretions, so large complicated membrane bound organelles are present in the eukaryotes. So, here in this diagram we see the connection between the DNA and the chromosomes, so here towards our left we see a DNA strand which is a 2 nanometer wide strand, so the DNA wraps over the protein complex molecules which we call them as histones, so here we have those histones these are histones 1, 2, 3, 4, 5, 6 and the DNA wraps over them and this kind of structure in which we have a histone and the DNA we call it as a nucleosome. So, then these histones they turn around and then they make some wider structures, so we come up to a 30 nanometer filament right here in this section, then this these sections they these structures they they super coil on themselves to make those further bigger fibers and then up till they reach into the chromosome the width is 1400 nanometers, so if we look into the chromosome now we can recognize there are kind of different arms in it, so which we call it as sister chromatids, remember this is just one chromosome but we have two chromatids and then somewhere in the middle we see a constricted part we call it as centromere, so the middle part of the chromosome we call it as centromere whereas the terminals we call them as telomeres. Please remember these nomenclature while we are discussing the heterochromatin and eukromatin parts, so chromosomes if they are stained with their dyes they give different coloring patterns we can come up with dense heterochromatin region and we can come up with light regions which are called as eukromatin regions, so dense regions obviously they are densely stained with the dyes and they take more color and light regions take less color, so if we look into the gene expression the heterochromatin regions are packed, so the enzymatic machinery cannot reach there, so there is these regions are poorly transcribed or poorly expressed whereas if we look into the eukromatin regions, so they are mostly highly expressed. Here is the diagram in which we can see the relationship between heterochromatin and eukromatin, so you look into these nucleosomes which as we have seen earlier these are the combinations of DNA and histone, so they are quite jam packed with one another, so obviously the enzymes it is hard to go and to access the DNA which is embedded in between. So there are different modifications on the DNA or on the histones that bring about those structures here we see them, so for example there are histone methylations in which methyl groups are added to those histones and in that case the system moves towards this side, so it becomes eukromatin and same way we see that there are some other methylations on some other amino acids that can move back into the other direction also. So histone deacetylations and histone methylations and there are some other complex proteins which get attached and may give us this heterochromatin region and whereas the reverse processes they give us this eukromatin region, so here we see in the eukromatin region the histones are quite spaced and DNA can be accessible, so this is the region why we see that this eukromatin part is expressed more as compared to the heterochromatin part. So eukaryotes are distinguished by the presence of prominent nuclei they have larger genomes and their chromosomes are relatively complicated.