Cell : The Unit of Life Selina biology Class 9 chapter 2

Cell : The Unit of Life Selina biology Class 9 chapter 2

Cell is the structural and functional unit of all living organism  all living organism are made up of cell

Cell : The Unit of Life Selina biology Class 9 chapter 2

Cell –

It is the Fundamental Structural and Functional Unit of the all living organism

https://en.wikipedia.org/wiki/Cell_(biology)

All living organism are made up of the cell

The Invention of the Microscope –

ANTON VAN LEEUWENHOEK – 

• He was a Dutch Scientist
• A. V. Leeuwenhoek constructed 1st Microscope
• he made many microscope
• the microscope made by Leeuwenhoek are known as ” Simple Microscope” 
• They are called as Simple microscope because it consist of ” a Single Biconvex Lens”  

Cell : The Unit of Life Selina biology Class 9 chapter 2

Discovery of cell –

Robert Hook ( 18 July 1635 – 3 March 1703) – 

• He Constructed Compound Microscope
• it is known as Compound Microscope because it was developed by using Two Lenses
• he observed ” Slice of cork” and find that it was made up of ” Box/ Compartment like Structure “
• he gives it name ” Cell” after  Latin name ” Cella” meaning ” Small Room” 

Microbes in Human Welfare NCERT 12 NEET PYQ

Cell Theory –

The Cell theory Proposed by 2 Scientist

1)  Theodor Schwann 

2) Matthias Schleiden 

1)  Matthias Schleiden  – ( 5 April 1804- 23 June 1881) 

• Matthias  jakob Schleiden was a German Botanist 
• in 1838 he wrote a book ” Contribution to our Knowledge of Phytogenesis”  in this book Schleiden stated that ” Plants are composed of cells ” or ” Plants are made up of cell ” 

2) Theodor Schwann (  7 December 1810 – 11 January 1882 ) 

• Theodor Schwann was  a German Physician
• Schwann stated that ” Both Animal and Plants are made up of Cells “

3) Rudolf Virchow ( 13 Oct 1823- 5 Sept 1902) – 

• Rudolf Ludwig Carl Virchow
• was a German Scientist
• in 1858 Virchow stated that ” All cell’s arises from Pre- Existing cell’s 

Cell Theory –

• Cell is the structural Unit of the all living organism and it is Smallest Unit of the body
• Cell is the functional unit of all living organism
• all cells arises from the Pre- Existing cell’s

Shape of Cell –

There are different shapes of the cells

The shape of the cells are as f0llows

1)  Disc – like

2) Cuboidal

3) Thread – like

4) Polygonal

5) Rectangular

6) Branched

Shapes of cells in Human Body

1)  Red Blood Cell ( RBC) – 

• Shape – Circular and Biconcave

2) Nerve Cell – 

• Shape – Long

3) White Blood Cell ( WBC) – 

• The WBC are Amoeba like cells in shape

4) Muscle Cell – 

• Shape – Long
• Shape of Plant cell – 
• Guard cell – The Guard cell of the stomata is – Bean Like  

• Cell Structure –

• Cell organelle/ Part of the cell – the parts of the cell are as follows –  
• 1) Non Living cell organelle –  
• a) Cell wall
• 2) Living Cell organelle – 
• a) Cell Membrane
• 3) Cell organelle present in Nucleus – 
• a) Nucleoplasm
• b) Nuclear Membrane
• c) Nucleoli
• d) Chromatin Fiber
• 4) Cell Organelle Present in Cytoplasm – 
• 1) Endoplasmic Reticulum ( ER)
• 2) Golgi apparatus
• 3) Ribosome
• 4) Mitochondria
• 5) Plastid
• 6) Centrosome
• 7) Granules
• 8) Vacuoles
• 9) Fat Droplets
• 10) Lysosome

• 

•  1) Cell wall –

• – it is only  present in plant cell
• It is Surrounded to the cell membrane
• cell wall is made up of ” Cellulose”  
• It is Freely Permeable 
• It gives shape to the cell

• 2) Cell Membrane –

• Cell membrane is made up of  a Protein known as ” Lipoprotein” 
• It is selectively Permeable
• It is also known as Plasma Membrane  

• 3) Cytoplasm –

• State – It is Semi- Liquid in state
• Appearance – It is Colourless
• Many cell organelle are present in the Cytoplasm
• following cell organelle are present in cytoplasm

• 1) Endoplasmic Reticulum (ER) –

• – it is a Network of small/Tiny Tubular Structure Scattered in the Cytoplasm
  – it is Classified into 2 Types Based on the Attachment Ribosome
  a) Rough Endoplasmic Reticulum
  b) Smooth Endoplasmic Reticuluma) Rough Endoplasmic Reticulum –
  – the Endoplasmic Reticulum have/ bearing Ribosome on their Surface is Known as Rough Endoplasmic Reticulum
  – These are Involved in Protein Synthesis
  b) Smooth Endoplasmic Reticulum –
  – When Ribosome are not attached with Endoplasmic Reticulum it is known as Smooth Endoplasmic Reticulum
  – it is Involved in Synthesis of Lipid 
• 2) Ribosome –
  – It is Discovered by George Palade in 1953
  – It is the Site of Synthesis of Protein 
• 3) Mitochondria –
  Shape – It is Cylindrical/ Rod Shaped
  – Each Mitochondria is Double Membrane bound Structure with Outer Membrane and Inner Membrane
  – The Outer Membrane Forms the Continuous Limiting Boundry of the Organelle
  – The Inner Membrane Forms Infolding Known as ” Cristae “
  – it is the Place where Respiration Occurs
  – Mitochondria are Known as “Power House of the Cell”
  – Mitochondria Contain Own DNA 
• 4) Golgi Apparatus –
  – It was 1st Observed By ” Camillo Golgi” In 1898 hence It is later Named after after Him as “Golgi Body ”
  – it is Composed of Large Number ” Cisternae”
  – it is the Important Site of Formation of “Glycoprotein” and “Glycolipid” 
• 5) Lysosome –
  – Lysosome is also Known as ” Suicide Bag of the Cell “
• 6) Plastids –
  – Plastids are only Found in
  a) Plants
  b) Euglenoids
  – They Possess specific Pigment
  – on the basis of Pigments Plastids are Classified as Follows 

• 1) Leucoplast
  2) Chromoplast
  3) Chloroplast 

• 1) Leucoplast –
  – The Leucoplast are the Colourless Plastids
  – They are Varied in different Shapes and different Sizes
  – Amyloplast – It Stores Carbohydrates ( Starch )
  Eg – Potato
• 2) Chromoplast –
  – They are Different Coloured Plastids Like – Red, Yellow, Orange
• 3) Chloroplast –
  – These are Green Coloured Plastids
  – These are Present in Plants
  – They Take part in the Process of Photosynthesis

• 

• * Vacuoles –
  – It is the Membrane Bound Space Found in the Cytoplasm
  – These are Larger in Size in the Plants
  – These are Smaller in Size in Animals

• Selina biology Class 9 chapter 2

• * Nucleus –
  – Nucleus was 1st Described by ” Robert Brown”
  – it Contains Genes
  – It is Associated with Cell Division
  – It is Spherical in Size 
• NEET PYQ Chapterwise – Animal Kingdom 1