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  • Cells- The fundamental Unit of life If you remember, in our previous session we have

  • seen the basic difference between a living and a non- living thing and some of the characteristics

  • shown by living organisms. So today we will be looking at the 1st characteristic

  • in detail i.e the composition of an organism The trees in the forest the fish in the riverthe

  • birds in the sky the worm in the soilthe tiger in the jungle the cactus in the desert your

  • class mate in fact any living thing on this planet is made up of cells which are known

  • to be the building blocks of a living thing. Many many cells come together to form a living

  • organism. Besides this, some organisms like bacteria

  • are made up of only one cell. One celled organism is all together an individual itself which

  • can perform all the functions like any other multi-cellular organism.

  • Every living being performs various functions during its entire lifespan like respiration,

  • digestion, excretion, reproduction etc. the body has specific organs to carry out these

  • functions. These organs are made up of various types

  • of tissues; and tissues are nothing but a group of cells. So in short we can say that

  • the human body is composed of many cells.Just as bricks form the important part of a building,

  • cells make up an organism. So we can say that cells are the basic fundamental unit of life.

  • In 1665, Robert Hooke discovered cells. He observed dead cells within the cork of the

  • bark of a tree using an old basic microscope. He observed empty spaces contained by a wall

  • and named them cells because they resembled small compartments.

  • So we can say that what Robert Hooke observed looked something similar to a honeycomb structure.

  • We shall take a look at some features of a cell. So lets get started.

  • No. of cells: Based on the no. of cells an organism can

  • either be unicellular or multi cellular. As the word suggests Uni- is one cell and multi is many cells.

  • Shape of a cell: Cells are of various shapes. Majority of them

  • are round, spherical and elongated. But you know what gives a cell its shape..???

  • Just like a room gets its shape from its walls a cell gets its shape from a cell membrane

  • which is the outer covering of the cell. Soooo talking about shape of cells u know

  • a unicellular organism named amoeba has no definite shape it is irregular and it keeps

  • changing its shape. In multi-cellular organisms, cells are of

  • different shapes. Like for eg. A nerve cell is long and branched in structure while a

  • red blood cell (rbc) is spherical and concave.

  • Size of a cell:

  • Cells are very tiny in size and are not visible by the eye. Hence to view them we use a microscope

  • which is an instrument that magnifies and enlarges the image of a cell.

  • So did you all know that A smallest cell is 0.1 to 0.5 micrometer which is of a bacteria

  • while the largest cell is 170 mm x 130 mm in size which is the egg of an ostrich.

  • You must know that the Size of a cell is based on the function it performs and not on the

  • size of an organism. sooo.. The nerve cell in an elephant and a rat will be of the same

  • size.

  • A cell has many parts and it contains components which help in the proper functioning of the

  • cell.

  • We will have a look at them in detail in our next video.

  • Till then why dont you all try a small exercise

  • Exercise: try listing all the various types of cells found in a human.

  • Until now we have been saying that biology is all about study of life but life is composed

  • of many many cells which come together to form a living organism. Our planet consists

  • of a vast number of creatures; some may be formed of just one cell like we have seen

  • in an amoeba while others are multi-cellular No of cells can vary depending on the size

  • of an organism an elephant will obviously have more no of cells compared to a rat but

  • the size of a cell will remain the same as we have seen previously.

  • Also cells have a property of regeneration. Imagine you have got a wound on your knee

  • and your skin cells are damaged. But your body has a tendency to regenerate those cells

  • on its own. This is the most fascinating property

  • of cells.

  • So till the

  • next video follow your curiosity. Do subscribe for more videos on biology.

  • If you have any questions ask me in the comments below

Cells- The fundamental Unit of life If you remember, in our previous session we have

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B1 organism size shape living multi cellular

Cell Biology | Introduction To Cell

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    Study English posted on 2016/10/06
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