Cell class 9 | The Fundamental Unit of Life - Cell | Cell complete course by Vivek Raj Singh | Vivek Raj Singh | Cell class 9 | Cell Class 11 | The Spectrum Vision.

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Hello everyone I’m Vivek Raj and in today's session let us learn about the cell theory unicellular and multicellular organisms and the basic structure of a cell okay so now um you know what these what i have shown you here lists out the major events in cell biology and imaging now the cell we know is the basic and the most fundamental unit of life that is why the chapters name itself is the fundamental unit of life right okay one second okay let's just checking if my head is getting cut off okay i'll start with the slide once again cut that part all right and let's get started now this image in front of you lists out the major events in cell biology and imaging so what do i mean by that basically simply put the the basic or the most important milestones which have played a very very important role in the field of research with regard to cell , cell biology or cytology as we call it okay there are a lot of events lots of developments that have occurred through the years for example where did it all start it started with the discovery of the cell okay and when did that happen that happened in 1655 imagine such a long time back and it was Robert hook who observed the cells of a court tree through the through a primitive microscope even the microscopes back then weren't very well developed but with the basic microscope that he had he observed cork cells dead cork cells basically okay and then um after that in 1674 .

Leeuwenhoek discovered protozoa and in 1683. Leeuwenhoek again discovers bacteria okay all of these of course were live cells which were observed by Leeuwenhoek but then the first the person to have first observed cells whether it's dead or living um to have observed cells is most definitely Robert took but then the first living cell was observed by Anton Van Leeuwenhoek okay so let's remember that um do not worry too much about the pronunciation children of course it is important we must give a lot of respect to the people who have um brought in a lot of change to science as we know it today but then my personal suggestion to you is whatever helps you remember the spelling easily make sure you pronounce it that way okay uh but of course without too much of change from the original of course and then 1838 Schleiden and Schwann proposed the cell theory okay you need to wait for a bit to understand more about that which is why i have put this in green font here we'll be talking about that in a bit so hold on and then 1857 Colica describes mitochondria in muscle cells and then 1882 where coach used aniline dyes to identify bacteria which caused TB and cholera 1898 golgi stains cells with silver nitrate discovering the golgi apparatus so golgi apparatus as you know it it's named after the scientist who discovered it and his name is golgi okay and in 1931 we've reached the 1900s of course these are not the only findings in these years but these are definitely the major milestones in cell biology which is why they are worth being mentioned before we start with this chapter okay not that these are definitely going to come in your exams but as a as a responsible biology student of class 9 you must know all this okay in 1931.

Raskar built the first transmission electron microscope more advancements in microscopy came up a type of electron microscope high resolution electron microscope called transmission electron microscope and in 1965 commercial the first commercial scanning electron microscope which is another type of electron microscope was also discovered and in 1997 the cloning of sheep all of you must have heard of that story right so imagine 1655 to 1997 300 audios right uh approximately through which so many many changes uh came up and today even today every single day things keep changing things keep getting advanced in the field of science and especially in the field of life sciences or biology i think every few seconds people just keep discovering new things anyway enough of all that let us now come to cell theory which i told you is very important for all of us to understand uh basically the cell theory in the initial form that we knew it was proposed by uh a combination of postulates by three different scientists Schleiden Schwann and verso okay let's look at what exactly they uh they tried to suggest so these are uh the major contributors to cell theory as i said Schleiden Schwann and verso of course i've mentioned them but Robert Hook definitely writes because without hook we may not have known uh cell as it was discovered in the 1600s so these are the major contributors to cell theory and in addition to that let us also understand a few uh important points of course what you see here uh the first three points which i have put here on top um are cell theory in its basic original form okay so uh in addition to that today we must keep in mind that even these three points are important as part of cell theory because of the contributions of many different scientists so uh it says that all living organisms are made of cells okay every single living organism be it a bacterium be it a fungus be it a protozoan be it a human being plant or any other animal or anything for that matter simple or complex is not a problem every living organism is made of cells then secondly cells are the basic the fundamental unit of life do.

You actually know what that means why do we call cell as the basic fundamental unit of life in fact it is the finest unit okay in which life can be considered as being present or if a cell is dead then that's it if all the cells in a person is dead then that person is considered dead everything life started with one single cell and one single cell kept on evolving and even today it is evolving in many different forms knowingly or unknowingly mostly unknowingly obviously and that is how over thousands of years uh species are also evolving every single change happening at the cellular level would be considered responsible for every change that we see in life as a whole right because so many years ago when uh life on earth first began there weren't so many varieties of organisms there weren't so many millions of different species known perhaps there was a time when there was no life at all and then life started as one single cell which divided into two became four eight sixteen um and so on and on and on right and today we have so many different varieties that we see around us this is why we say cells although microscopic we can't see them with our naked eyes they are certainly considered the basic and the fundamental unit of life okay and then the third point here cells arise from pre-existing cells okay um so this is these are the three major points which Leiden Schwann and verso proposed based on their findings and discoveries um like Schwann for example uh based her studies on animal cells Schleiden based his studies on plant cells and virtual within a few years he added on his findings also okay not that they actually worked together and came up with it and then additional pieces of information which came up in the later years hereditary information is passed from cell and then all cells have the basic uh pretty much the same basic chemical composition we know DNA or nucleic acids.

All of you would know what DNA is i'm sure children these are i think back in mine iron standard i don't remember having known the terms DNA , RNA and all that but these days um also the covet pandemic also has opened up interest uh in everyone's minds about a lot of life forms and how DNA and RNA function and things like that so you all know what what it is it's basically a biochemical substance found in our cells basically the most important biochemical components in our cells okay and then energy flow occurs within cells all of these three what uh we have mentioned at the bottom are additional points which you can add to the cell theory in the form that we know it today okay and now let's think about it the cell uh the simplest of cells may look simple what does this look like actually for you well um when i look at it although the color is like a like a beautiful blue yellow and a purplish tinge in the middle to me the shape and everything looks like either the eye of an organism uh oh when i say i it reminds me of the the fried eggs the half boiled or the fried eggs in the bowls i uh form okay anyway if that's if that makes it easier for you to remember please do picturize it that way so that it's easier for you to draw the cell also uh the cell membrane basically every cell is made of a membrane a nucleus in the middle and the cytoplasm around the nucleus okay so cells may look simple at one glance but actually it is not as simple as you may think an animal cell would look like this when cut open obviously not exactly cut open but then this is just there as a form to help us visualize whatever components are inside a cell okay animal cell and here we go a plant cell the shape itself is totally different right and then a bacterial cell may be even different as compared to these two but most importantly for us in the nine standard cbse level uh the most useful thing is to understand what a plant cell looks like and what an animal cell looks like we must know the clear comparison between the two of them okay so let us move ahead and uh also understand that cells in general not just in human beings although the picture here shows only in human beings but in general cells can be of various shapes and various sizes it's not like cells are always represented as a circle or as a hexagon or as any polygon no not really cells are of various shapes they can be of various sizes of course we say they are microscopic but we say the ovum or the egg.

Egg cell in humans that was also a cell the sperm is also a cell you can see all those pictures here everything is marked out here the brain cell neurons the heart cell liver cell your red blood cells your white blood cells your skin cells so on and on and on every type of cell having many different shapes and sizes right so coming back to the point that i was saying the egg cell we're saying is also a cell so the egg that you eat most most commonly we eat uh chicken's egg or ducks duck eggs are also common i think quail eggs are also smaller than chicken eggs ostriches eggs are considered to be very very huge right do you think they are also one single cell or do you think they are a group of cells think about it and let me know your thoughts in the comment section below or in the chat box because i will be watching this while the premiere is happening okay uh is an ostrich's egg hence egg or a duck's egg all of this are they considered to be single cells or are they groups of cells because if human egg is a single cell it it it makes sense to imagine them also as single cells right but then they are not microscopic why so then is it true to call them single cells these are all questions that we must think about let me know what you think in the comment section below okay now coming to the cell structure of an animal cell uh today children i will not be going into explaining the details of each of these because in our upcoming sessions we are going to be understanding the functioning and appearance of each of these very very uh well okay at a level deep enough for a nine standard cbsc child but for now let us understand what goes into making an animal cell .

Okay so um as you can see all these parts which are mentioned here they are called cell organelles okay so uh what is it all of these terms are important to understand an organism we i am an organism and i am made up of many different organ systems each of my organ systems is made of many different organs what do i mean by an organ system my digestive system is an organ system which is made of organs such as my stomach my small intestine my large intestine and so on even liver pancreas all of them my respiratory system is another organ system which is made up of organs like my lungs my um my trachea my nose my all of those everything together forming an organ system they die from everything my circulatory system is also another organ system made up of many different organs okay so organ system organism i mean sorry organism first and then organ system and then organ each organ is made up of many different tissues and many different tissues each type of tissue is made up of many different cells cells inside one single cell what you see are organelles once again let me repeat that children because this is a basic concept to get clear in your mind organism organ system organ okay tissue cell organelle okay super duper important because it forms the basic of your understanding about life as a whole so in an animal cell in a typical animal cell you would find all of these you would find although you may not be required to know each of these in detail some of the major organelles that we will be learning in this chapter of course as i told you earlier the plasma membrane or the cell membrane that you can see here and inside that is the cytoplasm this entire portion which you see inside the plasma membrane is the cytoplasm and the nucleus the beautiful purple colored nucleus right and then what are the other things additionally you would also have to learn about organelles like the endoplasmic reticulum which is of two types rough endoplasmic reticulum which you can see here and also smooth endoplasmic reticulum which you see here rough perhaps because of its appearance rough appearance we will discuss all that okay let me control myself and not burst out all of that surprise right away because we need to reserve a little bit for upcoming sessions also okay and then ribosomes ribosomes are also super duper important organelles inside a cell okay nucleus even within the nucleus .

You have a nucleolus and in addition to that you have thread like components which we call chromatin okay and then we also have golgi apparatus the golgi vesicle peroxisome secretory vesicle vacuoles in animal cells there are very very tiny vacuoles which are a little different in plant cells i will show you that also very soon and then smooth endoplasmic reticulum i've already told you that lysosomes microfilaments centrosomes and then microtubules cytoplasm i've already told you cytoplasm by the way do remember it is not a cell organelle it is rather the fluid medium within which all the cell organelles are lying embedded okay so i told you imagine it like the bullseye form um or if you want to think of more complex roles to each of these think of it now in the in the view that you are seeing it right now the bull's eye has zoomed in to take the shape of a cheesy vegetable omelette imagine it like that nucleus um give it the name of uh one of your favorite vegetables peroxisome maybe green chilies uh nucleus probably can be chopped onions mitochondria can be some other vegetable like carrot or something else and anything anything and everything that comes to your mind but all i want you to have in mind children is the clear picture of what an animal cell looks like okay let's not make things complex this is it just be familiar with these names until we meet again in the next session okay this is about the animal cell what about in a plant cell look at that beautiful green structure the shape and structure itself looks very different from the animal cell animal cell is more or less rounded in shape not exactly but more or less okay whereas a plant cell is usually drawn as a polygonal structure okay so all of these are the major parts of a planter of course it would also have the plasma membrane nucleus and cytoplasm but in addition to that plant cells also have something that we call the cell wall what you see here the cell wall cell wall is a rigid wall literally it's a wall that even surrounds the cell membrane whereas animal cells don't have it why is it there we will learn it in the upcoming sessions but for starters let me tell you cell wall is there because plants need additional rigidity additional structures to give them additional rigidity whereas animal cells don't really need that kind of support okay now what is the other major difference you would find in a plant cell chloroplast look at that chloroplast and inside a chloroplast you would find sub structures like the thylakoid membranes stored starch granules and so on all of us have heard about the process called photosynthesis you've been hearing this from your primary school days probably photosynthesis surprisingly or interestingly happens inside the the cell organelle called chloroplast.

Because we don't have a chloroplast we are unable to carry out photosynthesis okay it's nature's way of keeping plants the most important organisms on this planet life-sustaining organisms i would say on this planet okay and then the vacuole look at the vacuole uh what is special about this you as you can see if you compare it with the previous image we have seen animal sales vacuum is just this much in size whereas in a plant cell the vacuum is occupying so much of space inside the cytoplasm right again there is a very strong reason to that which i will be explaining when we talk about the organelle vacuole okay for now just understand vacuole in plant cells is much bigger in size as compared to an animal cells vacuole okay and in addition to that all of the other normal cellulose cell organelles which any typical cell including animal cells would have but these are the major differences cell wall chloroplast and the appearance of the vacuole okay and with that let us come to the quiz time the much awaited quiz time okay i will give you not more than 10 seconds to answer each question i will certainly be watching who's the smartest and fastest and giving me the answers okay so stay with me till the end at the end again homework question those of you who are new here i will be signing off only after giving you a homework question and let's see who's going to be answering best and fastest and that as well let's get started with the question the first living cell was discovered by Leeuwenhoek , Darwin , Hook newton and your time is up the answer is low and hulk probably many of you said the answer is hook but i think i told you this very clearly the first living cell note that point was discovered by Anton Van Leeuwenhoek but then Robert hook was the first to discover any cell at all but then what he saw was dead cells dead cork cells next one a multicellular organism has single cell many cells all the cells similar none of these okay and your time is up the answer is many cells multicellular unicellular uni stands for one multi stands for many okay so a multicellular organism like us or like any other animal or plant has many cells whereas a unicellular organism like an amoeba or a bacterial cell or a bacterium may have just one cell which making up its entire body which is why we call them unicellular organisms okay now Robert hook first observed the cell in dash i think i told you the answer just now a couple of minutes ago cork leaves flower roots and your time is up the answer is cork definitely okay now dash actually means a little room.

What do you think tissue organ organism cell use your common sense this is something that you know i don't think i have told you this directly in today's session but relate all these terms with a little room your timers up and the answer is sell okay now uh this is because in ancient days the tiny rooms are tiny chambers used by monks of that time of those times in Robert hopes times they were called as cells which is why when Robert hook observed these cells under the microscope for the first time the moment he saw them under the microscope those cells or those little chambers or rooms are what were what came to his mind so he decided to name them cells okay now largest cell in the human body is the sperm cardiac cell muscle cell or the ovum and your time is up the answer is ovum ovum is much larger than the sperm for your information if you did not know this ovum is the largest cell in the human body and every other cell as i said has its own shape and size basically designed in such a way that it can perform its respective function optimally neuron for example your nerve cell has a specific or a typical shape and size um your red blood cells have a typical shape and size white blood cells have a typical shape and size and so on and on and on so that they can perform their respective functions optimally most efficiently everything its shape and size of a cell is designed based on its functioning okay now the longest cell in the human body is the sperm neuron muscle cell or ovum for people who are wondering what a neuron is it's a nerve cell okay yes and your time is up the answer is neuron it's a long cell it's one of the longest cells or rather the longest cell in the human body a nerve cell it makes up your brain your spinal cord and all your nerves why would it be very long obviously so that it can transmit information from one part of your body to another right okay.

And that's about it well done all of you who have got all the answers correct rest of you it's all right all that matters is that you have participated well enough uh through the session and uh now let us have a quick recap not exactly recap let's let me remind you that you now know about the cell theory about unicellular and multicellular organisms and about the basic structure of a cell okay of an animal cell and of a plant cell we will be talking about the functions of each cell organelle in our upcoming sessions so stay tuned do not miss any of our sessions before we sign off let me give you the homework name the special type of cells which receive information from surroundings wow how are we linked to our surroundings name the special type of cells which help us perform this particular function okay so let's see who's giving me the answer fastest and best.

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Cell class 9 | The Fundamental Unit of Life - Cell | Cell complete course by Vivek Raj Singh | Vivek Raj Singh | Cell class 9 | Cell Class 11 | The Spectrum Vision.