What Is Cell? Cell Structure, Functions, Characteristics, Types, And Cell Theory
Hello everyone, Welcome to home Tuition Academy. I'm here with a new topic from FSc first year biology that is " What is cell? and note about Cell Theory".
First I have explained cell portion and then cell theory portion.
The Cell Portion contain Cell definition, Cell discovery, cell types, Cell Size And Shape, Cell Structure, Cell characteristics, And Cell Functions.
The Cell theory Portion contain Old Concept of cell theory and modern concept of cell theory.
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So let's begin.....
1 • CELL:
Cell is the basic structural and functional unit of living organisms.
As per definition we can say it is the structural unit and as well as functional unit of living organisms.
but what is the main idea of structural unit and functional unit.
• STRUCTURAL UNIT:
As we know that the 100% body of an organism Is made up of cells, it means that cells create it's structure that's why it is called structural unit.
• FUNCTIONAL UNIT:
Different components of the cell perform different functions which is actually a reason of an organism body functions, so as these functions are due to cell so cell is called functional unit of living organisms.
• DISCOVERY OF CELL:
Cell was discovered by Robert Hooke in 1665.
The question arise that how he discovered it?
He take a cork of bottle and place it against compound microscope, he found that, that piece of bottle cork consist of some rooms like structure he name these room like structures cell.
Who said that cells are actually a live entities?
Anton Van Leevionhooke study that cell through compound microscope and he notice that their is a slight movement in cell. From that he proposed that cell can move at some extent, he called it live entities.
• SHAPE AND SIZE:
Cells have indefinite size and shape. The size and shape of the cell depends upon place of it's location.
• CELL STRUCTURE:
Cell is composed of many components, here we will give a short intro to every component one by one.
Cell Wall:-
The outer most layer of plants cell is called cell wall.
- It is absent in animal cells.
- It is non living in nature.
- it provide support and maintain structure of the cell.
• Cell Membrane:-
The outer most layer of the animals cell and inner to cell wall in plants cell is called cell membrane or plasma membrane.
- Cell membrane provide support and protection to the cell.
- It allow materials to pass through it.
- When cell need something cell membrane allow that element to inside of the cell and if there is some elements unwanted in cell, cell membrane expell that element outside.
Cytoplasm:-
The area between plasm membrane and nucleus is called cytoplasm.
- It is aquatic area which consist of liquids.
- Cytoplasm consist of small organic components called organelles, that perform different Structures of the cell.
- All metabolic reactions take place in cytoplasm.
Nucleus:-
The central part of the cell that control all activities of cell is called Nucleus.
- It is a major part of the cell.
- It is also called master organelle of the cell.
- It is consist of chromosomes.
Nucleolus:-
A dark area of the nucleus which contains ribosomes is called nucleolus.
- Nucleolus is the place of synthesis of proteins and other important molecules.
Nuclear Membrane:-
Nucleus is covered by a layer called nuclear membrane.
- Nuclear membrane help to separate nucleus contents from cytoplasmic contents.
• CYTOPLASMIC ORGANELLES:
Endoplasmic Reticulum:-
A membrane bounded organelle of the cell that looks like Platened stacks.
- It transport materials from one part of the cell to another part.
- It also help to transfer materials from one Organelle to another.
- Another function of it is protein synthesis because in rough endoplasmic reticulum surface there is ribosomes present which help in protein and cholesterol synthesis.
Golgi Bodies:-
Membrane bounded thread like structure that spread all over the cytoplasm.
- The main function of the golgi apparatus or golgi Bodies is transport materials from cell to vacuole that further expell it to external of the cell.
Mitochondria:-
A double membrane bounded organelle of the cell that provide central service to the cell.
- Mitochondria produce or generate energy in the form of ATP and provide it to cell for performing different activities.
- As it generate energy so it is called power hous of the cell.
Lysosomes:-
As we know that stomach is an organ that helps to digest and grind our food we eat, so Lysosomes do the same in cell.
- Lysosomes digest unwanted materials and pass it to golgi Bodies to expell.
Vacuole:-
A small sac like structure that are found in many numbers in the cell is called vacuole.
- Vacuole is a liquid storing organelle of the cell that stores extra liquid and release it to external through cell membrane.
• TYPES OF THE:
There are two types of cell on the basis of structure.
A. Prokaryotic Cell.
B. Eukaryotic Cell.
A. Prokaryotic Cell:-
Those cells that don’t have true nucleus and membrane bounded organelles are called prokaryotic cell.
- Pro... Means...False, Karyon...Means... Nucleus.
It means that they have only a dark area which we can suppose nucleus.
- It’s size is about 0.1 to 0.5 micro, meter.
- These cells are present in unicellular organisms.
- These cells have whether DNA or RNA.
- A place where it’s genetic materials are suspended, called nucleoid.
- It divide and reproduce asexually and binary fission.
B. Eukaryotic Cell:-
Cells that have true, clear and membrane bounded cell with well developed membrane bounded organelles are called Eukaryotic Cells.
- Eu... Means... True, Karyon... Means... Nucleus.
- it's size is about 10 micro meter to 100 micro meter.
- These cells are present in multicellular organisms.
- It's division occurs by sexually and asexually process both.
• CHARACTERISTICS:
There are many characteristics of the cell some of them are given below:
- Cell consist of cell membrane which help in the transport of materials across the cell.
- Cell produce energy with the help of mitochondria.
- Cell digest unwanted materials by the help of Lysosomes.
- Cell perform the division process.
• FUNCTIONS:
Cell perform number of functions:
- Cell provide structure to an organism.
- It provide support to the organisms as that's why a plant can stand steady.
- Cell provide the process of materials moving across the cell membrane.
- Cell provide energy in form of ATP to an organism for it use in different activities.
2 • Cell Theory:
Many biologists have done different work in cell subject. They try to make a statement about cell as a theory, three of them succeed in making a theory, called cell theory.
Theodor Schwann, Matthias Jakob Schleiden and Rudolph Virchow had proposed a well developed and acceptable theory about cell which is called cell theory.
There are two concepts or versions of the cell theory:
A. Old Concept.
B. Modern concept
As cell theory was proposed in about 1800 it was consist of three statements or points, we call it old Concept.
Old Concept of the cell theory consist of 3 points:
A. Old Concept:-
1. All living Organisms are made up of cells. (This is simple I think no explanation needed).
2. Cell is the basic unit of life/ living organisms. (As it is the definition of cell).
3. All new cells arise or produce from pre-existing cells.
Pre-existing cells are actually parent cells. As parent such as mother give birth to it's child as parent cells produce new daughter cells.
Now let's write about Modern concept of the cell.
As scientists are continuely researching and studying cells, so they modify or improve cell concept to a modern form and we called it modern concept.
B. Modern Concept:-
Modern concept of the cell is Also consist of three statements or points:
1. Energy Flows within the cell. The energy produced by Mitochondria in the form of ATP, flows inside the cell from one place to another.
2. Genetic information transfer from one cell to another.
We can also say that genetic information pass from parents cell to daughter cells.
As father and mother genetic information fuse together and locate in the offspring cells.
3. The chemical composition of all cells are the same.
Every cell have same amount of protein, carbohydrates and other chemicals as compared to other cell.
I think this is enough for now....
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