Welcome today we will talk about a very interesting concept and that is cell and human body or any organism is composed of trillions of cells when I say trillion it is a thousand billion and 1 billion is a thousand million, so you can understand the extent or the number of cells through which our body is composed of now there are various kinds of organisms some organisms are unicellular that means they have a single cell for example amoeba Paramecium all the functions of production excretion digestion respiration are taken by a single cell, so they are single cellular on the other hand we have multicellular organisms very specialized cell perform specialized works so here are some of the brain-teasers for you if you are able to solve those you are all set with the chapter s let's start with the very basics now cell is a very structural unit of an organ the cell is equivalent to or comparable to a break now brick is used as a building material for construction similarly cell is a building material for an organism, so you have the cells which are assembled in a body of each and every organism usually the structure of cell or the arrangement of cell we see is a honeycomb structure that I see, and this cell was first observed in the call and call was obtained from the bark of a tree this corn was seen back in 1665 by Robert Hooke so Robert Hooke when he observed the cork cell are these cells were actually dead cells, and he could observe only my new traces of those later on nearly 150 years later after he discovered that there were very good mechanisms to observe the cells very microscopically with higher magnification that was seen, and therefore you had huge varieties of microscopes that were developed which could go into very mind. You detail with a very good magnification, so microscope is an instrument which is used to see minute organisms are my new particles that are present or a smaller cell that could be seen so as I said cell is a very basic structural unit there are various arrangement and combinations of cell the cells vary in shape size and color so different cells have different purpose that could be seen some cells are very small they have micrometers so point one micrometer 0.5 micrometer, and therefore we used microscope to see those now again those cells are not directly visible so what I need to put a some dye or stain so when we put some stain or die because of those you have the color of the cells that are seen and if all those cells become very obvious under a microscope on the other hand there are cells which could be seen by a normal eye or any unaided eye we see that is we do not require any microscope to see the god for example egg of an ostrich or a gopher hen so that's again a sin now it is unique you have an eggshell with which has the white part which is known as albumin and the center part which is the yellow part which is known as egg yolk so albumin and egg yolk and that switches one cell which is considered as a single cell unicellular organisms we already said amoeba Paramecium usually nicer for example when I say amoeba it's unique because amoeba does not have a defined shape it has pseudopodia so all of those are pseudopodia pseudo means false, so these are considered as false leg and these keep on changing their shape, so amoeba keeps on changing its shape amoeba reproduces by binary fission which we will understand in early their classes on reproduction of our unique cellular organism are of as usual organisms that next year's multicellular when I say multicellular you have a specialized cell that are present so specialized cells for blood specialized cells for muscles specialized cells for nerves that are present, and their arrangement again is very important to understand, so we have our PCs which are spherical so as you can see RBC here are spherical you have muscle cells which are spindle shaped you have nerve cells which are elongated cells, so those are different types of cells that are seen different shapes that are seen as I said amoeba does not have any shape it has pseudopodia that appears and disappears as it moves and feeds, so you have the amoeba that moves and captures the food particle changes it shapes then you have WPC which also changes the shape similar to an amoeba, but amoeba is a full-fledged organism WBC is not a film fledged organism so that's the difference that we need to understand also all the components of cell are enclosed in the cell membrane so within a cell membrane we can see there is nucleus and cytoplasm is the jelly-like substance that fills up the space within the cytoplasm there are numerous organelles that are present these would be in the form of Ecology bodies bros ribosomes, and then you have, and you clear this nucleus is important because it's a center for inheritance it's not just a center for inheritance, but it is also a control center which controls all the activities of the same this nucleus is surrounded by a membrane which is known as nuclear membrane similar to the cell which is surrounded by a membrane Which is known as cell membrane now this cell membrane is permeable that means there is exchange of things which takes place from outside between the two cells that is present there is a medium and this medium helps to exchange the things that there so that's another important aspect that we need to understand a very important concept that we would come up here as the size of the cell has no relation to the actual size of a body you have an elephant which is huge all right which is a small both of them have a nerve cell with a function of coordination and control that is present all the law says beta elephant or beta ran along and branch, so they perform the same function of transferring the message, but it's not that the size of the cell would be bigger in the case of elephant as compared to a red, so the size of a cell has no relation to the size of the body of an actual animal that is present okay now there are various things that have specialized rules for example roots help in absorption of water leaves helps in the process of photosynthesis so each organism being a plant or feed human being have specialized rules that are present so as I said cytoplasm has numerous organelle ease within the jelly-like substance that is there and the nucleus this nucleus again has a center which is known as nucleolus within the nucleus you have chromosomes have the genes and these genes are responsible for carrying the genetic information or the heredity information that is present a very good example to experiment by ourselves is a cheek cell, so you can just take a toothpick and take a sample of your cheek cell you can stain it with iodine and methylene blue and then look under a microscope, but you would see it would be a structure something like this and this is what is the structure of the cells present in the cheek cell of a human being now as you can see you just have a cell membrane there is no cell wall is absent and animal cell wall is only in the plant cells why it is present in the plant cell is important it is mainly for the protection of the plants cannot physically move from one location to another so there if there is a variation in her temperature speed event moisture conditions humidity conditions water plant need is a protection and this protection could be obtained through the cell wall which gives it a shape and a rigid structure so that is something that is very important to understand the next important thing to understand is the nucleus along with the cytoplasmic together constitutes the protoplasm root of loss is known as the living substance of the cell that is very important now each of the cells be in a plant cell or an animal cell has because Mike uses the empty space that is present so in plant cells there is one big make you and animal cells there are numerous small vacuums since in the plant cell there is one big vacuole what would happen is this big vacuum would give a shift to the nucleus on one side so in the plant cell nucleus is present on one side however under an animal cell which is irregular in shape you have nucleus moreover in the center, and you have numerous values that are present which are smaller again since the plant has a cell wall it has rectangular more or less animal cell is more or less circular the rectangular shape is maintained due to the cell wall it means the sheep and the rigidity that is there again were very important town is prokaryotes and eukaryotes prokaryotes do not have a well organized nucleus however you Chi droids have a well organized nucleus example of prokaryote are bacteria blue-green alga, so these do not have a well-defined well organized nucleus that is present but well-defined new that is present again the plants will have plastids chloroplast is one good example this has green color which is chlorophyll and this provides the green color to the leaves so the pigment that gives green color to the leaves is through the chloroplast and these chloroplasts or the plasters are present in plant cell they are absent in animal cell you have flagella that are present however cilia that is present however that is absent in a plant cell if put in a hypertonic or a hypertonic solution the animal cell routine does not retain its shapes it bursts because it does not have a cell phone however plant cell does not burst because it has a cell wall so that's again a very interesting study that we do here a very interesting fact for you is about this skin now the outermost or the topmost layer of the skin is dead whim it's believed that we carry nearly 2 kg of dead skin every day and even if you wipe your finger to remove the dust in that process you shade out numerous millions of dead cells that are there and that's how we understand that the topmost layer of the skin which is considered as dead cell does not have any sense, and therefore you do not have a sensation over there similarly when you are cutting your knees those are dead cells, so they do not have any cells, and therefore you do not have a pain sensation their pain sensation comes only when the contact skin gets hurt or there is injury to the neighboring areas the next important thing that we understand is the storage so implants, and you have starch as the storage however in animal cell glycogen is the storage cloud can synthesize the nutrients by themselves animal cells cannot synthesize their nutrients by themselves, so those are some of the most important differences that we see the number of mitochondria is present in class unless is compared to animal cell similarly the lysosomes are rarely noticed in plant cells but yes they are seen in animal cells, and they are also called as societal bags those are some of the important differences that we have seen between the plant cell and the animal cell will be bringing in many important lectures for you the very important components of cell so stay tuned for further lectures is t subscribe have a wonderful day
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