[Music] the fundamental unit of life do you know what is the fundamental unit of life it is cell cell is called as the fundamental unit of life do you know who discovered this cell it's Robert Hook in 1665 Robert Hook observed a thin slice of cork under his own microscope he found small box-like structures they were like small rooms of a honeycomb Robert who called these boxes as cells the meaning of the word cell is little room so cells are the building blocks of all living things that means all living things are made up of cells certain organisms are made up of only one cell means the whole body of the organism is only one cell such organisms are called single cell or unicellular organisms uni means single examples of unicellular organisms are bacteria amiba parium and camid monus some organisms are made up of many cells such organisms are called multicellular organisms multi- means many examples of multicellular organisms or plants trees animals and human beings all cells of a multicellular organism develops from a single cell cells produce new cells of Their Own Kind by cell division all cells come from the pre-existing cells so here we learned three important points about these cell these three important statements are collectively called as cell theory let us see what are those one all living organisms are composed of cells this means that whether an organism is a single cell bacterium or a complex multicellular organism like a human all life is fundamentally made up of cells two the cell is the basic structural and functional unit of life that means cells are the smallest unit of life that can carry out all the processes necessary for an organism to live cells are the building blocks of life and perform various functions depending on their special job three cells arise from from pre-existing cells this statement is given by rodolph virco it tells that the new cells are formed from pre-existing cells through the process of cell division these three principles are collectively called as the cell theory we learned that multicellular organisms are made up of many cells is the whole body of a multicellular organism is made up of similar kind of cells no m multicellular organisms are made up of different types of cells now let us see the different types of cells of our body muscle cells blood cells nerve cells bone cells ovam sperm cells fat cells Etc why these cells are in different shape and in different size the shape and size of these cells depends on the function they perform you know that in our body we have different systems to perform different tasks for example heart pumps blood liver secretes digestive juices kidneys filter the blood and brain controls the body this means that in our body different jobs are done by different parts just like how different people in a factory does different jobs jobs we call this as division of labor we will observe this division of labor inside a cell also a cell is made up of different parts and each part performs a specific function now let us see the different parts of a cell generally a cell has three main parts they are cell membrane nucleus and cytoplasm cell membrane or plasma membrane cell membrane is also called as plasma membrane plasma membrane protects the inner components of these cells just like how our skin protects our inner parts plasma membrane controls the entry of materials into the cell and also controls the exit of materials from the cell to the outside environment it works like a checkpost between two different states you know that at the checkpost checking of vehicles and verification of licenses is done in the same way cell membrane verifies the materials and decides whether to allow them inside or not it permits only the selected materials for this reason cell membrane is called selectively permeable membrane now let us see how the exchange of materials takes place between the cell and its surroundings the exchange of gases takes place between the cell and its surroundings by a process called as diffusion do you know what is diffusion the movement of molecules from a higher concentration area to low concentration area is called diffusion here we can see the concentration of oxygen outside the cell is high compared to to the concentration of oxygen inside the cell so the oxygen molecules they move from higher concentration to lower concentration that means these oxygen molecules they enter the cell through the plasma membrane this process is called diffusion there is one more phenomenon through which the transfer of water molecules takes place between the cell and its surroundings it is osmosis the movement of water molecules from a place of lower solute concentration to a place of higher solute concentration through a semi-permeable membrane is called osmosis let us understand osmosis with a simple activity take some raisins raisin is covered by a thin semi permeable membrane and it has a thick sugary pulp inside that means the raisins have high concentration of sugars inside now take a beaker with some water now drop the raisins in this water the concentration of the sugar in the water is less compared to the sugar inside the raisin so the water in the beaker is called a hypotonic solution now osmosis takes place and the water molecules move into the raisin through its semi-permeable covering and the raisins swell up this is called as Endo osmosis now take another Beaker and prepare a thick sugar hyponic solution the concentration of the sugars should be higher than the concentration of sugars in the swollen raisin now place the swollen raisins in this Beaker the water present in the raisins comes out into the hyponic solution and the raisins become shrunk this is called EXO osmosis so this activity shows us that in osmosis water molecules move through a semi-permeable membrane from a hyponic solution that is lower solute concentration to hyponic solution that is higher solute concentration ation then how do the transfer of other materials takes place into the cell for the entry of some materials into the cell energy is required this kind of Transport is called active transport now let us see the composition of the plasma membrane can we see the structure of plasma membrane through a compound microscope no the structure of plasma membrane can be seen only through an electron microscope plasma membrane is made up of carbon compounds like lipids and proteins plasma membrane performs a special function in amiba organisms like amiba engulfs the food materials through their cell membrane this process is called endocytosis cell wall now let us see the structure and function of cell wall both plants and animal cells have cell membrane but plant cells have one more covering over the cell membrane called as cell wall cell wall lies outside the plasma membrane do you know with which material the cell wall is made up of the plant cell wall is made up of cellulose cellulose is a type of complex carbohydrate it gives structural strength to the plants sometimes plant cells undergo a condition called as plasmolysis do you know what is plasmolysis if the water present in a living plant cell is lost through osmosis then the contents of the cell shrink away from the cell wall this phenomenon is called plasmolysis importance of cell wall in plants cell walls in Plants fungi and bacteria help them handle watery environments without bursting plant cells absorb water when placed in diluted surroundings causing the cells to swell as the cell swells it presses against the cell wall creating pressure the cell wall pushes back with equal force balancing the pressure of the swollen cell unlike animal cells plant cells can tolerate big changes in their surroundings due to the presence of cell wall nucleus now let us look at the structure of nucleus the nucleus is covered by a nuclear membrane this nuclear membrane has two layers the nuclear membrane also has pores these pores are called nuclear pores materials enter and exit the nucleus through these pores the nucleus has chromatin inside do you know how the chromatin looks like like it just looks like a tangled thread but it changes into rodlike structures called chromosomes during cell division chromosomes contain DNA and protein let us look at an example to understand the functioning of chromosomes your phone has software to control its functioning in the same way every cell has DNA to control its functioning our phones have different apps to execute different tasks in the same way DNA has different genes to execute different tasks the functional segments of DNA are called genes that means DNA is made up of genes genes are the building blocks of DNA do all cells have a distinct that means clearly defined nucleus no in certain single cell organisms like bacteria the nuclear membrane is absent the nuclear region is undefined and contains only nucleic acids such type of nucleus is called nucleoid the organisms whose cells lack a nuclear membrane are called pro carots pro means primitive or primary karot or Carion means organism then what are the cells with a clear nucleus called as eukaryotic cells are there any other differences between procaryotic and eukaryotic organisms in procaryotes besides the absence of nuclear membrane the membrane bound cell orals are also absent on the other hand the eukariotic cells have nuclear membrane as well as membrane enclosed organel so by this we understand that procaryotic organisms have poorly organized cell organal compared to UK carotic organisms cytoplasm we have learned that cell is covered by cell membrane do you know what is inside the cell the space inside the plasma membrane of a cell is filled by a semi-transparent fluid this semi-transparent jelly like material is called cytoplasm what does this cytoplasm consists of cytoplasm consists of water minerals and en enzymes it is the place where many biochemical reactions takes place there are so many organel floating in the cytoplasm these organal are called cell organal these cell organal keep the cell Alive by performing different tasks each kind of cogal performs a specific function such as making new materials in the cell clearing up the waste material from the cell and so on let us look at structure and functions of cogels this is smooth endoplasmic reticulum rough endoplasmic reticulum ribosomes Golgi apparatus lomes mitochondria plastids and vacul each of these organel performs a specific function let's see some short details of each of these organal rough endoplasmic reticulum this is called as protein factory because it makes new protein molecules smooth endoplasmic reticulum this is called fat Factory because it makes new fat molecules Golgi bodies they are called dispatch centers because they handle the packaging and distribution of materials that are prepared in in the endoplasmic reticulum mitochondria it's called Powerhouse of the cell because it produces the energy from the glucose vacul they are called storage bags they store different materials lomes they are called suicide bags because they contain the digestive enzymes these digestive enzymes digest the foreign materials like bacteria and damaged cells plastids they are called pigment stores because plastids contain different pigments these are the special cogels that are found only in plant cells plastids also help in photosynthesis now let us see why do cells have different cell orals let's find the answer to this question with the help of an example we cannot play football Cricket basketball and Tennis all together in the same court different courts are required to play different games similarly in a Cell a lot of chemical activities takes place different chemical activities require different conditions and Machinery to takes place all reactions cannot take place in the cytoplasm so they need separate organel to keep these chemical activities separate from each other cells use membrane bound organal these organal are called cell organal can we see these cogels under a compound microscope no we cannot see the cogels under a compound microscope but cogels can be seen with the help of an electron microscope let us study the structure and functioning of cogels in detail and endoplasmic reticulum now let us learn about the structure and functions of the endoplasmic reticulum first let us locate the endoplasmic reticulum inside this cell yes this is endoplasmic reticulum we can see that it is located around the nucleus this looks like a network of tubes and sheets it is made up of some special membrane this membrane of endo plasmic reticulum is similar in structure with the plasma membrane the endoplasmic reticulum is of two types this is rough endoplasmic reticulum and this is smooth endoplasmic reticulum the rough endoplasmic reticulum is like a network of sheets folded around there are so many dot-like structures present in the rough endoplasmic reticulum called ribosomes due to this ribos omes it has a rough appearance so that's why endoplasmic reticulum with ribosomes is called rough endoplasmic reticulum now let's see the functions of rough endoplasmic reticulum rough endoplasmic reticulum makes new protein molecules with the help of ribosomes that's why rough endoplasmic reticulum is also called as protein factory functions of smooth endoplasmic reticulum smooth endoplasmic reticulum appears as plain sheets and tubes smooth endoplasmic reticulum synthesizes or makes new fat molecules what happens to the new protein and fat molecules made by the endoplasmic reticulum these proteins and fats are used by the cells to make new cell membrane we know that cell membrane is made up of lipids and proteins so for the formation of new cell membrane during cell division these two materials are required the process of formation of new cell membrane is called membrane biogenesis some proteins and fats are converted to enzymes and hormones and are secreted out of the cell to execute various functions apart from protein and lipid manufacturer what are the other functions of endoplasm mic reticulum endoplasmic reticulum helps in the transport of materials between various regions of cytoplasm it also allows the transport of materials between cytoplasm and nucleus two it provides surface for many important biochemical reactions to take place three in vertebrates smooth endoplasmic reticulum plays an important role in DET toxifying the toxins and drugs so these are the structural features and functions of endoplasmic reticulum Golgi apparatus now let us see the structure and functioning of Golgi apparatus this is GGI apparatus let us observe its structure it looks like flattened bags or vesicles these vesicles are arranged parallel to each other and form Stacks called as systems now let us see the functions of Golgi apparatus in a factory the machines that manufacture the item and the machines that pack them are different once items are made then they are sent for packing and dispatch in the same way in our cells protein molecules are manufactured in the endoplasmic reticulum and then the are sent to the Golgi apparatus for modification packing and dispatch the proteins that are manufactured by the endoplasmic reticulum are modified and stored in the Golgi apparatus when needed they are packed and dispatched in the form of vesicles Golgi apparatus performs three important functions one storage of materials two modification of material materials three packaging and dispatch of materials the Golgi apparatus gathers simple molecules and combine them into more complex molecules then it packs these big molecules in vesicles Golgi apparatus May store these vesicles for later use or dispatch them out these vesicles are delivered to different cell organel inside the cell sometimes these vesicles are delivered outside the cell to the Target location since these cell organel were discovered by coggi they are called as Golgi apparatus lomes first let us locate lomes inside the cell these are lomes let us see the structure and functions of lomes lomes are sack like organel the lomes are formed from the GGI apparatus lomes are covered by a membrane outside and filled by a fluid inside this fluid contains digestive enzymes now let us see the functions of lomes their main function is to clean the waste and unwanted materials inside the cell they work as Waste Disposal system of the cells what kind of waste materials are found inside the cell sometimes a bacteria virus or some undigested food particle that enters the cell these things are considered as a waste and they are to be removed sometimes the parts of the cell are damaged or worn out these parts are also considered as waste or unwanted materials these kind of materials are cleared by lomes sometimes if if a cell is damaged the cellular components try to repair it using materials like proteins and fats that they get from endoplasmic reticulum but if the damage is beyond the repair lomes help the cell to self-destruct lomes burst and the digestive enzymes digest the components of the cell that is why lomes are called as suicidal bags of these cells mitochondria these are mitochondria let us see the structure and functions of the mitochondria mitochondria are double membrane organal each mitochondria has two membranes one outer membrane and two inner membrane the outer membrane is porous that means it has pores the inner membrane is deeply folded do you know why the inner membrane of mitochondria is deeply folded mitochondria need more surface area to carry some special reactions in which a special energy rich molecule called ATP is released so to provide more surface area the inner membrane is deeply folded now let us see what are ATP ATP means adenosin triphosphate these are n energy rich molecules in our cells many reactions takes place and all these reactions need energy and in our cell there are so many new materials are produced so for the production of these new materials ATP are required that's why ATP are called as cell currency or energy currency of cell generally in a cell nucleus has DNA and it passes the information to the cell orals like endoplasmic reticulum to make proteins necessary for cellular activities that means all the cogels follow the instructions of the nucleus but here in case of mitochondria it is a bit different mitochondria they have their own DNA and ribosomes so they can manufacture some of their own proteins that's why mitochondria are sometimes called as strange organal this is all about mitochondria plastids now let us see the structure and functions of the plastids these are the cell orals that are found only in plant cells plastids are of two types one chromoplasts two leucoplasts first we see about chromoplasts chroma means colored the plastids that have color pigments in their stroma look colored and are called as chromoplasts the plastids that contain chlorophyll and carry out photosynthesis are called as chloroplasts so chloroplasts are green in color due to the presence of chlorophyll some chloroplasts contain yellow or orange colored pigments along with the green colored pigment chlorophyll now we will see the second type of plastids leucoplasts lucco means white so lucco plasts are colorless that means white plastids their main function is storage of materials do you know what are the different materials that are stored by the lucco plasts starch oils and protein granules are stored by the lcop plasts externally that means from the outside look plastids look similar to mitochondria if we have observe the internal organization of a chloroplast the innermost membrane is folded and arranged in Stacks called as Grana the space between the Grana is filled by stroma just like mitochondria plastids also have their own DNA and ribosomes and can make their own proteins now let us see about vacul vacul are the sacks for storage of materials materials in the form of solids and liquids are stored in them in animals the vaces are in small size whereas in plant cells the vacul are in very big size and occupy 50 to 90% of the cell volume how do bigger vaces help the plant cell the vaces in the plant cell are filled with cell sap they help the plant cell in two ways one provides turgidity and rigidity to the cell two they store many important materials like sugars amino acids and various organic acids and some proteins in unicellular organisms vacul perform some important functions for example in organisms like amiba the food enters the food vaces where it get digested and absorbed in the same way contractile vaces are formed to collect and excrete the excess water and waste materials this is all about vaces cell division now we will see the process of cell division cell division is the process by which new cells are formed from pre-existing cells organisms need new cells for growth repair of their damaged tissues and for reproduction growth means adding new cells to the body so in growing organism continuous cell divisions produce new cells sometimes our cells may get damaged to replace the damaged cells new cells are required and these cells are formed by cell division for the process of reproduction organisms need to produce new reproductive cells or sex cells these cells are also produced by cell division now let us see the different types of cell division what are the two different types of cell division there are two different types of cell division that is one mitosis two meosis first let us see mitosis most of these cells are divided by this mitosis this type of cell division helps in the growth and repair of body for example a boy grows into a man for this his bones and muzzles ought to be grown growth in the bones and musles means formation of new bone and muzzle cells these new cells are formed by the mitosis in the same way for repair and maintenance of our body new cells are required for example if someone Falls and get their hand or leg skin bruised in a few days we see new skin is formed this dis is because of mitotic divisions of the skin cells do you know our skin loses 30,000 to 40,000 cells a day all these cells are to be replaced with new cells so these new skin cells are formed by mitosis in mitosis one parent cell divides into two daughter cells these two daughter cells are identical and have same number of chromosomes as Mother cell for example the number of chromosomes in a Mother cell are 46 the daughter cells also will have 46 chromosomes each but for the process of reproduction some special cells are required these special cells should have half number of chromosomes of the parent cell so to achieve this reproductive cells are produced by special type of cell division called as meosis the main purpose of myotic divisions is to produce reproductive cells or gamuts now let us see how this is different from mitosis in myotic division the parent cell divides into two daughter cells that has the same number of chromosomes as their parent that means if the parent has 46 chromosomes then the daughter cells also have 46 chromosomes but this is not end of myotic division these two daughters cells divide further and produces four daughter cells these daughter cells will have half the number of chromosomes as compared to the Mother cell that means if the mother cell has 46 chromosomes finally the daughter cells have 23 chromosomes each so in myotic division the number of chromosomes reduces to half the sperm cells formed in the testes of males and egg cells formed in the ovary of females are formed by myotic division so the gamuts or sex cells have half the number of chromosomes compared to the other cells of our body why do sex cells have half the number of chromosomes this is because during fertilization the male gamut with 23 chromosomes fuses with female gamut with 23 chromosomes and forms a zygote with 23 pairs of chromosomes that means 46 chromosomes this zygote further divides by mitosis and develops into a baby