hello everyone myself dr. Suresh today we'll be discussing about cell and subcellular organelles so we are all aware what is a cell and what impact it has got with the life right so at your school level you have studied cell is basis of life right and what makes it basis of life the cells like prokaryotes eukaryotes right plant cells are prokaryotes animal cells are eukaryotes and they have different subcellular organelles and they have different cell wall and cell membranes in their structure right so coming to the structure of cell. Okay, first we'll see the basic structure of the cell and what are the subcellular organelles. Then we study the differences between prokaryotic cell and eukaryotic cell.
A typical cell consists of a well rigid cell membrane in eukaryotes and in case of prokaryotes, it is a cell wall. So as we all belongs to eukaryotic type, so our concern is to study about eukaryotic cell. And here if you see in the picture like the typical composition of cell along with the subcellular organelles here you can make out plasma membrane and then you have microtubules, centrioles, nucleolus, golgi complex, smooth endoplasmic reticulum, rough endoplasmic reticulum, lysosomes, cytoplasm, mitochondria, free ribosomes, nucleus, chromatin, nuclear pore, nuclear envelope and furthermore ribosome.
So all these subcellular organelles are present inside the eukaryotic cell and each subcellular organelle is having their own functions right so which is mandatory for functioning of the cell right. Coming to the cell which is a structural function unit of life as we have stated earlier it is a basic unit of biological activity. And why we are studying the cell here in biochemistry?
So we are all aware. So the chemical reactions which are happening in the living system or living cell. So to study or to know these chemical reactions, it is mandatory for us to know the basic composition of cell, what it is made up of and what are all the things are present inside the cell and what are their functions, right?
So that's why we are again studying about the cell in biochemistry. So here, as I mentioned earlier, There are two types of cells prokaryotic cell and eukaryotic cell right prokaryotes They as I mentioned they lack well-defined nucleus and possess relatively simple structure Okay, and in bacteria also the same prokaryotic cell. They don't have any cell membrane They have just a cell wall and eukaryotes as I mentioned it's a enclosed by a membrane. Okay uh, that is nucleolus right and they have in higher organisms like animals this eukaryotic cell is present like in human beings and in animals so coming to the differences like eukaryotic and prokaryotic here you see in red color i mentioned about the prokaryotes and in black color i mentioned about eukaryotes the size of the cell also vary as i mentioned cell membrane the presence or absence of cell membrane and cytoplasm right so all these things vary in prokaryotic and eukaryotic cells you So if you see the size of the prokaryotic cell, it is 1 to 10 micrometers. Okay.
And in eukaryotes, the size is like huge, like 10 to 100 micrometers. Cell membrane. There is no cell membrane in case of prokaryotes. They do have cell wall.
And in case of eukaryotes, they have a rigid cell membrane. Cytoplasm. It is viscous. No subcellular organelle is present in prokaryotic cell.
But in case of... might uh eukaryotes they have subcellular organelles as i mentioned as i've shown in the previous slide nucleus ribosomes smooth smooth endoplasmic reticulum rough endoplasmic reticulum mitochondria lysosomes peroxisomes centrioles all these makes the subcellular organelle inside the cell such as especially eukaryote so furthermore in respect to subcellular organelle uh presence or absence eukaryotes and prokaryotes you can make out here nucleus it is present inside a nuclear zone but in case of prokaryotes it is well defined nucleus membrane will be there and in case of nucleolus it is attached with the dna okay and eukaryotes there is no nucleolus there is simply nucleus okay in which dna is present mitochondria is absent in prokaryotes which is present in eukaryotes you can make out golgi complex which is absent in prokaryotes and it is present in eukaryote cytoskeleton totally absent in case of prokaryotes and in eukaryote it is present cell division it is of fission type you might have studied your school binary fission right so all these things are there in case of prokaryotes but here mitosis in case of eukaryotes the cell division is mitosis see here the diagrammatic representation of prokaryotic and eukaryotic cell the size of the cell what i have mentioned here 0.1 to 10 micrometers but in case of eukaryotic cell the size is huge which is measuring from 100 to sorry 10 to 100 micrometers right you can make out the differences here you see here what are the mentions plasma membrane there is no plasma membrane in place of plasma membrane in prokaryotes it is having a cell wall there is no cytoplasm in case of prokaryotes there is a well-defined cytoplasm in case of eukaryotes DNA is present in both but they in prokaryotes they have clear nucleolus but here we have in prokaryotes we have nucleus so coming to the cell organelles okay which to be separated then how you are going to separate the subcell organelles especially as we are talking about eukaryotic cell so different subcell organelles are there golgi complex endoplasmic reticulum ribosomes mitochondria cytoplasm peroxysomes lysosomes so different subcellular organelles so how to differentiate these subcellular organelles so how you isolate them okay so there is a technique called ultracentrifugation by using the centrifugal force so i'll give you an example like suppose in a bucket in a bucket of water if you take different weights of glasses okay and drop them in the water and rotate the water so the weighted one the most weighted one will drown first Right, similarly the subcellular organelles in eukaryotic cell have different molecular weight. So when you apply a centrifugal force, so based on their molecular weight, the weighted one will sediment first than the lighter one.
Like this way we can segregate or isolate subcellular organelles in eukaryotic cell. So like this, so by applying centrifugal force, different subcellular organelles will be isolated at different centrifugal rate. suppose like here what i have shown example so like for 800 rotations per minute okay for 10 minutes if you do right so all you get is like membrane fragment cell membrane you can be isolating similarly 13 000 rotations per minute for 10 minutes if you do you will isolate nucleus okay and the same way if you apply 1 lakh rotations per minute For 60 minutes you can isolate subcelular organelles like mitochondria, lysosomes, paraxysomes and their sediments. Similarly fragments of endoplasmic reticulum also be isolated by applying 2 lakh rotations per minute for 3 hours of duration. And finally ribosomes will be gated and which is present in the cytosol.
So in this table I have clearly mentioned what are all the subcellular organelles can be isolated by applying how much amount of centrifugal force okay that means number of rotations okay right if you take nucleus you are supposed to apply 600 to 750 rotations into 10 minutes right so the marker will be like dna the main component present in nucleus is dna right and coming to lysosomes if you take the main substance present in lysosomes the marker is cathapsin so by identifying particular marker you can make out that the particular subcellular organelle be isolated right mitochondria the enzyme which is present in mitochondria like krebs cycle the enzymes like alpha-ketoglutarate dehydrogenase or like succinate dehydrogenase if you want to isolate the cytoplasm your glycolysis will be taking place in the cytoplasm so by isolating lactate by identifying lactate dehydrogenase you can make out that the isolated subsilyl organelle is cytoplasm so this way you can make out or you can separate subsilyl organelles the main technique to be used is ultracentrifugation Thank you.