 what is a cell? first the contents definition of cell basic types of cells structure of cells function of cell and number of cells in an organism first we discuss what is a cell definition cell is the smallest independent unit of life if we define cell it is a unit of life all living organisms when we take the concept of life there is one thing in our mind that they are made up of cells it is the same as when we take the concept of building in our mind we immediately know that it will be made up of bricks like this human or other living organisms the units that make them they are the cells there are some properties of cells the first property of cells is that cell can grow when a cell is produced it adds to its size so what we will say in size cell is growing the second property of cells is that they divide with the passage of time there are some cells when they are formed after cell division they do not divide but most of the cells they have ability to divide cells synthesize biomolecules there is a complete machinery in the cell in which cells you can synthesize proteins lipids,carbohydrates if we look at the overall role of cells if we look at the overall role of cells they work as a structural unit they also work as a functional unit of living organisms basic types of cells broadly if we look at the two basic types of cells if we look at these details we are having a large number of different types of cells in our body if we count we have red blood cells white blood cells we have T lymphocytes B lymphocytes in epithelial cells we have different types of cells in detail there are many types of cells but broadly if we look we can categorize them into two major groups they are the prokaryotic cells and the eukaryotic cells structure of cell there are three basic parts of the cells the first one is the plasma membrane then cytoplasm and then nucleus the outer boundary of cell it is the cell membrane after that cell in the center we have nucleus whereas between cell membrane and nucleus that is called cytoplasm if we look at these basic components these are the eukaryotic cells we have basic components if there is a prokaryotic cell then there will be no nucleus only DNA will be present these are the basic components apart from these cells there will be many other components like the structure of the membrane the eukaryotic cells the cytoplasm there will be many organelles and the nucleus the chromatin material these three are the basic components apart from these there will be many other components functions of cell cells in our body it is performing all activities of life all the activities of life of all the properties they are due to the cells so if we simply classify it or categorize it then before number one the property of the cell or its function is the building block it makes all the bodies living organism apart from this all the cell activities whether it is cell secretions cell contraction absorption transportation transportation is a simple example oxygen transfers the whole body these are the red blood cells which are transferring it in this way different types of cells they are performing different jobs number of cells how many cells can be in a living organism some living organisms have only one cell these are called unicellular the example of unicellular organism which we have one bacteria bacteria are unicellular organisms if we look at the categories of animals we have protozoa we have amoeba parametrium plasmodium these are the unicellular organisms so we can say that there are many organisms which are having only one cell but majority of the animals they are having more than one cell even if we look at the human there are trillions of cells in the human when I was in ninth grade I studied that there are 60 trillions of cells but the recent research says that there are about 37 trillions an average human size which is about 60 trillions of cells which is about 60 trillions of cells which is about 60 trillions of cells there are 60 trillions of cells in the human if you take a big animal like an elephant elephant is 100 times more than human elephant is 100 times more than human ok the recent research says that there are 37 trillions of cells in the human so how many are there in an elephant you multiply 37 trillions from 100 we have more than this where there will be more cells multicellular organism there will be more cells some multicellular organisms which are having very few cells simple eukaryotes they are having even they may be up to 100 cells in their body