1. SCIENCE & TECHNOLOY STD :- 9TH CLASS
CHAPTER 5) CELL THE UNIT OF LIFE

2. CELL : THE UNIT OF LIFE
CELL :Defi. The common basic structural & functional unit of living things are called cell
It was discovered by scientist Robert Hook (1665)
He found cell structure like honey comb & labeled them as “cell”.
Cell means in latin word “small rooms”.

3. Types of cell
Unicellular : The animal made up by just one cell are called unicellular cell.
Ex. Amoeba, euglina, paramoecieum.
Multicellular : The animal made up by many cell are called multicellular cell.
Ex. Man, horse, ant.
CELL theory : It was proposed by M.J. Shleiden & Theodore Schwann that “ All plants are composed by cell i.e. cell is basic unit of plants.
In 1885 Virchow modified this theory that “omnis celula a celula .“ which means “all cell arise from existing cell.

4. Postulate of modern cell theory
All organisms are composed by cell
Cell is the structural, functional unit of life
All cell arise from pre-existing cell
Every organism starts its life as a single cell

5. Morphology of cell
The unit used to measure the size of cell is micrometer (µm).
Smallest cell :- mycoplasma, galliseptium (0.1 µm)
Largest cell :- eggs of ostrich (18 cm)
Size of cell varies greatly from 0.1 µm to 18cm.

6. PLANT CELL & ANIMAL CELL
Cell wall present in Cell wall absent in plant cell animal cell.
Chloroplast present Chloroplast absent in
Plant cell animal cell.
Vacoules are larger & Vacoules are smaller &
More in number fewer.
Plastid is present Plastid is absent.

7. Cell structure (part) 1) cell wall 2) cell membrane 3) cytoplasma
4) cell organelles

8. Cell wall
Defi. Plant cell have another rigid outer covering on cell membrane is called cell wall.
It is freely permable
It is made by cellulose
Funtions :-
It protect inner part
It give perticular shape to the cell.
It give strength to the cell.

9. CELL MEMBRANE
Defi. Every cell is bound by a thin covering which seprate the content of the cell from external enviroment this is called cell membrane.
It is selective permable
It is made by lipid bilayer
It is delicate & elastic covering membrane.
FUNCTIONS:-
It protect the inner part of the cell
It maintain shape of the cell.

10. Cytoplasma
Defi. The fluid which lies between the plasma membrane & nucleus is called cytoplasma
It is jelly like substance
Many organelles lies in cytoplasma
FUCTIONS:-
It store vital substances like glucose , vitamin
Cellular chemical reactions take place in it.

11. CELL ORGANELLES
Defi. Various cell organelles embended in cytosol they are called cell organ.
1) nucleus
2) golgi bodies
3) mitochondria
4) lysosomes
5) plastid
6) vacoules

12. NUCLEUS
It is large spherical body generally laying at the center of the cell.
It covered by double layered nuclear membrane
This membrane is porous which allow to transfer of products from inside the nucleus to cytoplasma
Fuction:- 1) It control cell division.
2) it control all metabollic activities of cell
3) it involved in transmission of heredity character from parents.

13. Golgibodies It discovered by scientist “ Camillo Golgi” .
It have 5 to 8 sacs which resemble deflated balloons placed parallel to each other
It is chemical factory of the cell.
Fuction:-
1) It is secretory organ of the cell.
2) It produce vacoules
3) It play important rule in the formation of cell wall & cell membrane.

14. Mitochondria
Defi. The powerhouses of the cell organelles is called mitochondria
It has double layer membrane
The outer layer is porous & the inner layer is deeply folded which is called cristae.
There are numerious mitochondria in animal cell & fever in plant cell.
Fuction:-
1) It produce energy rich compound like ATP.
2) It synthesis chemical compound
3) The cell uses energy stored in ATP to do mechanical works.

15. Lysosomes It has single layer structure
It bound in sacs filled with enzyme
It digest the waste material
It present in animal cell only but absent in plant cell.
Fuction:-
1)It is digestive system of the cell
2) It protect to the cell from bacteria , virous etc
3) When cell get old or damaged , lysosomes bursts & the enzyme digest the cell. Therefore it is called “sucide bags”.

16. Plastid They are double layer membrane structure
It present only in plant cell
It has two types namely-
a)chromoplast – coloured plastid
b)leucoplast – white / colourless.
Function:-
1) chromoplast help to convert solar energy into chemical energy.
2) chromoplast give colour to flower & fruits
3)leucoplast involved synthesis & storage of food like oil & proteins

17. vacoules It is bound by single membrane structure
They do not have any basic shape & size.
It is large storage sacs for solid & liquid content
The structure of vacoules changes according to need of the cell.
Function:-
1)It maintain osmatic pressure
2)They stored waste material & also food in animal cell.

18. THANK YOU
Created by :- Shri. Jagtap A.S.