Cell Theory And Its Structure

cell theory and its structure

Previous Topic :Cell : Paramecium

Cell Theory

As we all know that Robert hooke was the first biologist to observe dead cork cells with microscope in 1665 and later in 1834, another biologist, Dujardin a french biologist discovered the living part of a cell and called it SARCODE which is known as Protoplasm. In 1838 another German botanist, Mathias Schleiden discovered that all plant are made up of cells. In 1839 Theodor Schwann, also a German zoologist discovered that all animals are made up of cells.

In 1839 Theodor Schwann and Mathias Schleiden jointly stated what will all known as CELL THEORY, meaning that, all living things are made up of cells.top↑

After the statement of the cell theory, Hugo Von Mohl is the first biologist to applied cell theory [protoplasm] to the living substance in the cell. That is, is the person that tell us that we should be calling protoplasm "protoplasm".

In 1858 another biologist Rudolf Virchow stated that cells come from pre-existing cells.top↑

Cell Structure

Cell structure, how does a cell looks like ?
Cell generally doesn't have a specifically structure, am not saying cells doesn't have a structure, what am saying is the word CELL particularly, if I ask you that, what is the structure of a cell? You shouldn't have any answer to give me but if I ask you that, what is the structure of an egg cell? You should probably have answer for me.

All cells have different structures, it depends on the type, each type has a structure that fits it for its particular function.top↑

Structure Of Some Particular Cell

Structure Of Epidermal Cells Of Onion

structure of epidermal cells of onion

that is the structure of the epidermal cells of onion
Cells vary in size, that's cell doesn't have a specific size.

Most cells are microscopic, only few kinds are visible to naked eye or unaided eye, they ranges from about 0.025mm to about 0.25mm in diameter.

NOTE: There are exceptions to the above note like in eggs, eggs are cells.
chicken eggs are different from ostrich eggs, which also there cell's length will also be different.
NOTE : Ostrich egg cells are the largest egg cell. meaning Ostrich eggs are the largest eggs.top↑

Structure Of A Human Cheek Cells

Cells differ in shape:
a] Cells of the human skin are flat.

Structure of human cheek cells

that is the structure of human cheek cells.
b] Cells lining the intestine are cylindrical.

c] Red blood cells are disc shaped and biconcave while White blood cells are amoeboid.

d] Nerve cells are elongated ending in fine processes.

e] Liver cells are cubical.top↑

Common Structures and Characters To All Cells

a] Every living cells has a cytoplasm, a nucleus and a cell membrane.
In the nucleus is the protoplasm which is also called nucleoplasm.

Continuation On Cell : Paramecium

d] Structure : paramecium is a unicellular organism, just visible to the naked eye. It is between 0.15mm and 0.3mm long.
The shape resembles that of human foot or a slipper.

Structure of paramecium

e] Respiration : paramecium can respire with the use of oxygen that dissolved in the water which diffuses through the entire body surface into the paramecium.

So simply paramecium uses oxygen for respiration.

f] Osmoregulation : The protoplasm of paramecium, a higher concentration of salts than the surrounding water in the habitat. What am saying is that,
Water passes from the surrounding into the organism by osmosis.top↑

Paramecium has two contractile vacuoles, one at each end. These act alternately. That is, Each slowly enlarges, reaches its maximum size and then bursts, removing excess water from the protoplasm to the outside. This process is called osomoregulation that is, it is the control of water content of the protoplasm.

g] Sensitivity: paramecium can perceives changes in its environment and responds to them. It defends itself against the enemies by shooting out its trichocysts which may hurt or kill the predators. If it meet or encounter an obstacle, while in motion, the cilia will temporarily stop beating. Then it reverses the ciliary beat and moves back at a different angle. Then it resumes the forward motion in a new direction. This process or act is called avoiding reaction.top↑

h] Excretion: paramecium passes out carbon dioxide and nitrogenous waste product by diffusion, into the surrounding water through the entire body surface of the paramecium.

And the last one,
I] Reproduction : There are two types of reproduction, asexual and sexual reproduction.

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