Cell:-Fundamental unit of life..

What is Cell?

In the year 1665,' Robert hook' gave the name" cell "to those compartments that he observed in a thin section of cork..the study of cells is called cytology.meaning of cell is known as hollow..

Cell is known as the structural and functional unit of life..There are different types of cells ..They are as following:-

Nerve cell.

Muscle cell .

Bone cell.

Cells of glands .

Reproductive cell.

Blood cell.

These all are the cells present in a human body..

Cells are of two types:-1) Eukaryotic 2) prokaryotic cell..

Eukaryotic -The cell having a well-organized nucleus with a distinct nuclear membrane is known as eukaryotic cell..

Prokaryotic -The cell that lack a membrane -bound nucleus are called prokaryotic cells..

We often take the help of  a  microscope to observe cells as most of them are very small..But there are some large ones like the unfertiled  eggs of hen and fish,a juicy hair inside a lobe of citrus fruit like orange etc..

Do you know what are the differences between these cells??

No matter how different cells appear ,be they unicellular organisms or multicellular forms,all life process (nutrients, respiration, excretion, transport and reproduction)occur in a cell..Meant these are all cells..

What are the differences between multicellular and unicellular organisms??

Multicellular organisms -An organisms which is made up of more than one cell ,is known as multicellular organism..

Ex-We the humans etc..

Unicellular organisms -An organisms which is made up of only one cell is known as unicellular organism..

Cell organelles -it is the tiny component of cell..A cell has to perform many functions, including synthesis of substances, secretion of substances and digestion of substances to generate energy .. All These activities are carried out by cell organelles...

Now let's understand what is Typical

Plant and animal cell..

Typical plant cell-Usually  they are large than animal cell.

Chloroplast present.

Vacuole large and permanent.

Storage material is Starch grain..

Typical animal cell - Usually smaller than plant cell.

Chloroplast absent.

Vacuole small and temporary.

Storage material is Glyeogen granules..

Organisations of cell ...

The cell has an internal structure that keeps changing.Regarding it's part we have come far to know that some of them from its membrane itself. We shall study such parts under endomembrane system . There are some other parts that were formed due to the entry of an organism on to a cell.

ENDOMEMBRANE system and cell parts..

Endoplasmic reticulum, golgi body ,lysosome,cell membrane, nucleus etc.., fall under this category..These parts are membrane bound,enclose a space within that is partioned off from the cytoplasm and usually contain a fluid that differs from it. These parts have contacts and relations among themselves in various ways..

What is Cell membrane??

The cell membrane which plays an important role in the passage of materials across it . The structure of the cell membrane is visible only under the  electron microscope .it is elastic in nature and made up of mainly protein and fatty,oily substances cell as lipids. It is a bilayer membrane that forms a protective covering of the cell selectively permeable membrane..

What is permeable membrane?!

Permeable membrane is like a polythene from which the process of osmosis is done..

What is a cell wall??

Cell wall is a special feature of plant cell.Animal cell usually lack a covering outside the cell membrane.it is a hard ir elastic and porus covering about that renders a particular shape , support and protection to the plant cell.

What is cytoplasm???

The cytoplasm is a basic fluid in which,stored,secretory, excretory substance

are present..The water content of cytoplasm is usually large..

Fluid -A liquid like substance and jelly like substance is known as a fluid..

What is a nucleus ??

Robert brown saw a structure in the centre of the cell which he named as nucleus.,in the year 1831..This nucleus is known as the most important part of the cell..there is a thread like structure inside the nucleus which are known as Chromatin..they are mainly composed of genetic material.these appear as rods during cell division and are called as Chromosomes...

Nuclear controls and coordinates all functions of the cell. A bilayered nucleus membrane around the nucleus that is similar to the cell membrane,in most cell..

Endoplasmic reticulum - It is the network of interconnecting membranous structures filled with fluid ; covering most part of the cytoplasm...

Ribosomes - They are dense, spherical and granular particles either found free or attached to the endoplasmic reticulum.the main constituents of the ribosomes are RIBONUCLEIC ACID or RNA and proteins..

Functions- Ribosomes help in protein synthesis..

Golgi body- in 1898 a scientist called C . Golgi discovered these cells organelles on the cytoplasm of cells. They were found to originate from endoplasmic reticulum.they are filled with fluid vesicles, vacuole and closed sacs stacked together as parallel rows piled one above the other called cisternae.. they occur as an extensive network near the nucleus.in plants, they are known as dictyosomes...

Lysosome - they are small,sac like structures found regularly distributed in the cytoplasm.there shape may vary.lysosomes are membrane -bound vesicles  filled with digestive enzymes that can digest all types of organic matter....

Vacuoles - Fluid filled bodies of various shapes that usually contain storage products are called as vacuoles..(the term vesicles used earlier to represent very small vacuoles.)

Mitochondria - mitochondria are either cylindrical or spherical in shapes ,  their size ranging from 0.2 hu to 2hu.they are distributed through the cytoplasm..

Plastids- plastids,are the organelles found in most of the plants except Euglena,but are absent in animals..

The process by which the new cells are formed is known as division...And the cells which are formed by this process  are known as daughter cells..

Cell theory:-

Theodore Schwann was a zoologist while Schleiden was a botanist.Both had extensively studied cells and found that cells were those units that are formed the bodies of living organisms...

1) All living organisms are made up of cells,their communities and intercellular substances..

2)Cells are the structural and functional unit of living organisms..

3)Cells arise from pre-existing cells....

Try this questions if you understand the concept:-

Why are the cells usually so small??

Are cells flat??

What is a Cell?A cell is the basic structural and functional unit of all living organisms. The term 'cell' was introduced by Robert Hooke in 1665 when he observed compartments in cork. Cells can be classified into two main types:

  1. Eukaryotic Cells: Have a well-defined nucleus enclosed by a nuclear membrane.

  2. Prokaryotic Cells: Lack a membrane-bound nucleus.

Types of Cells:

  • Nerve cells

  • Muscle cells

  • Bone cells

  • Gland cells

  • Reproductive cells

  • Blood cells

Key Components of Cells:

  • Cell Membrane: Selectively permeable, providing protection and controlling material passage.

  • Cytoplasm: Jelly-like fluid where cellular processes occur.

  • Nucleus: Contains genetic material and controls cell functions.

  • Cell Organelles: Including ribosomes (protein synthesis), mitochondria (energy production), lysosomes (digestion), and Golgi bodies (modifying and packaging proteins).

Cell Theory:

  1. All living organisms are composed of cells.

  2. The cell is the basic unit of life.

  3. Cells arise from pre-existing cells.