Give important points or summary of the Chapter "Cell - The basic unit of Life" Of Class 9th.
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Answered by
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Hi there !!
The important points are as follows :
1. Cell is the basic structural and functional unit of all living organisms. All living organisms have derived their life from one single cell which is fertilized egg. This cell divides and differentiates to form tissues, organs, organ systems and an organism.
2. Cells were first discovered by Robert Hooke in the year 1665. He observed a thin slice of Cork and found dead cells of cork which resembled to a structure of a honeycomb. He named these units cell.Cell is a Latin word for " a little room ".
3. Later, various discoveries took place which led to the advancement of cell biology. The main discoveries are as follows :
° Robert Hooke- Discovery of cell ( in 1665). °Robert Brown - Discovery of nucleus ( in 1831)
°Purkinjie - Coined the term Protoplasm ( in 1839)
° Schleiden and Schwann - Proposed the cell theory ( 1838 - 1839)
°Rudolf Virchow - Stated that new cells arive from preexisting cells.
° Knoll and Ruska - Designed the electron microscope ( in 1932)
4. Cells can be seen through an instrument called microscope which magnifies an object several 100 times.
5. Organisms are of 2 types on the basis of the number of cells :
a) Unicellular organisms - containing single cell
b) Multicellular organisms - containing more than one cell
6. Organisms are of 2 types based on the structure
a) Prokaryotes - those with a undefined nucleus + absence of nuclear membrane
b) Eukaryotes - those with defined nucleus + presence of nuclear membrane.
7. Cells have different shapes and sizes. The smallest cell in human body is the RBC while the largest is the OVUM(egg).
8. There are different parts of cell , here's a brief description about them.
*°Cell membrane : Outer covering of the cell which protects the cell and gives it a shape ( is selectively permeable)
°Cell wall : Only present in plant cells, is thick and rigid due to presence of CELLULOSE.
°Nucleus : The control center of the cell. Contains DNA which has genes , necessary for inheritance of life.
°Endoplasmic reticulum
. SER -Manufacture lipids ( fat molecules)
. RER - Manufactures proteins with the help of ribosomes.
°Golgi Apparatus : Helps in transport of substances within the cell mainly with the help of vesicles .
° Lysosomes : Suicide bag of cell , helps in digesting worn out cells.
° Mitochondria : Generates energy in the form of ATP molecules. called Powerhouse of the cell.
° Vacuoles - Store food , water and wastes . Very small and few in animal cells, occupies 50-90% of cell volume in plant cells.
° Plastids - Are of 3 types :
. Chromoplast coloured Plastids ,
. Leucoplasts : Colourless Plastids
. Chloroplast : Green colored Plastids , containing chlorophyll ie necessary for photosynthesis.
* Movement through cell membrane occurs through the process of diffusion ( in case of gases) and osmosis ( in case of liquids )
Osmosis is a special kind of diffusion which refers to the movement of solvent molecules from a region of high to low concentration.
Different types of solution :
1. Hypotonic solution : in which the solvent concentration is higher outside than inside .
If cell is placed in it, it swells
2. Isotonic solution : Same concentration on both sides.
No change in shape.
3. Hypotonic solution : In which the solvent concentration is higher inside than that of outside.
If cell is placed in it , it shrink.
DONE !!
The important points are as follows :
1. Cell is the basic structural and functional unit of all living organisms. All living organisms have derived their life from one single cell which is fertilized egg. This cell divides and differentiates to form tissues, organs, organ systems and an organism.
2. Cells were first discovered by Robert Hooke in the year 1665. He observed a thin slice of Cork and found dead cells of cork which resembled to a structure of a honeycomb. He named these units cell.Cell is a Latin word for " a little room ".
3. Later, various discoveries took place which led to the advancement of cell biology. The main discoveries are as follows :
° Robert Hooke- Discovery of cell ( in 1665). °Robert Brown - Discovery of nucleus ( in 1831)
°Purkinjie - Coined the term Protoplasm ( in 1839)
° Schleiden and Schwann - Proposed the cell theory ( 1838 - 1839)
°Rudolf Virchow - Stated that new cells arive from preexisting cells.
° Knoll and Ruska - Designed the electron microscope ( in 1932)
4. Cells can be seen through an instrument called microscope which magnifies an object several 100 times.
5. Organisms are of 2 types on the basis of the number of cells :
a) Unicellular organisms - containing single cell
b) Multicellular organisms - containing more than one cell
6. Organisms are of 2 types based on the structure
a) Prokaryotes - those with a undefined nucleus + absence of nuclear membrane
b) Eukaryotes - those with defined nucleus + presence of nuclear membrane.
7. Cells have different shapes and sizes. The smallest cell in human body is the RBC while the largest is the OVUM(egg).
8. There are different parts of cell , here's a brief description about them.
*°Cell membrane : Outer covering of the cell which protects the cell and gives it a shape ( is selectively permeable)
°Cell wall : Only present in plant cells, is thick and rigid due to presence of CELLULOSE.
°Nucleus : The control center of the cell. Contains DNA which has genes , necessary for inheritance of life.
°Endoplasmic reticulum
. SER -Manufacture lipids ( fat molecules)
. RER - Manufactures proteins with the help of ribosomes.
°Golgi Apparatus : Helps in transport of substances within the cell mainly with the help of vesicles .
° Lysosomes : Suicide bag of cell , helps in digesting worn out cells.
° Mitochondria : Generates energy in the form of ATP molecules. called Powerhouse of the cell.
° Vacuoles - Store food , water and wastes . Very small and few in animal cells, occupies 50-90% of cell volume in plant cells.
° Plastids - Are of 3 types :
. Chromoplast coloured Plastids ,
. Leucoplasts : Colourless Plastids
. Chloroplast : Green colored Plastids , containing chlorophyll ie necessary for photosynthesis.
* Movement through cell membrane occurs through the process of diffusion ( in case of gases) and osmosis ( in case of liquids )
Osmosis is a special kind of diffusion which refers to the movement of solvent molecules from a region of high to low concentration.
Different types of solution :
1. Hypotonic solution : in which the solvent concentration is higher outside than inside .
If cell is placed in it, it swells
2. Isotonic solution : Same concentration on both sides.
No change in shape.
3. Hypotonic solution : In which the solvent concentration is higher inside than that of outside.
If cell is placed in it , it shrink.
DONE !!
thanks rohit bhai and Alice sisi
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Answered by
19
1) The structural and functional unit of life is cell .
2) Each living cell has capacity to perform certain basic functions which are characteristics of life .
3) ROBERT HOOKE ( 1665 ) first discovered the cell . He coined the term cell .
4) A.V. LEEUWENHOEK ( 1831 ) first studied the living cell .
5) ROBERT BROWN ( 1839 ) and SCHWANN ( 1839 ) proposed cell theory . It states .
* All plants and animals are made up of cells .
* Cell is basic unit of life .
* R. VIRCHOW ( 1885 ) suggested all cells arise from pre-existing cells .
6) Cells vary in number , shape and size not only in different organisms , but also in various parts of Same body .
7) Cells are enclosed by plasma membrane formed of lipid and proteins .
8) Plasma membrane is flexible and semipermeable - It regulates the flow of material into and out of cell .
9) The diffusion of water , solvent through a semipermeable membrane from a region of higher concentration to a region of lower concentration is called OSMOSIS .
10) In plant cell , a freely permeable cell wall formed of cellulose is present outside plasma membrane . It is protective and supportive layer .
11) The presence of freely permeable cell wall enables the cells of plants , fungi , and bacteria to exist in hypotonic media without bursting .
12) A true Nucleus is present . It is generally single - Spherical and central in position .
13) Nucleus is separated from the cytoplasm by a double layered membrane called NUCLEAR MEMBRANE .
14) PROTOPLASM . It is the living material of cell . PURKINJE coined the term Protoplasm .
15) HUXLEY regarded protoplasm as the PHYSICAL BASIC OF LIFE .
16) CYTOPLASM is the fluid content of cell present between nucleus and plasma membrane . It contains METABOLITES and ORGANELLES .
17) Cells are two types I.e. PROKARYOTIC and EUKARYOTIC CELL .
18) PROKARYOTIC CELLS lack well organised nuclear membrane and membrane bound organelles . They have 70 S type of ribosomes .
19) EUKARYOTIC CELLS have proper Nucleus and membrane bound organelles . 80 S ribosomes are present .
20) ENDOPLASMIC RETICULUM is an electron-microscopic interconnected network of membrane bound tubes and sheets called CISTERNAE , TUBELES or VESICLES . It is of two types :- RER ( Cisternae are studded with ribosomes and involved in protein synthesis ) . and
SER ( Tubules are without ribosomes ) .
21) RIBOSOMES are composed of RNA and proteins , granular electron-microscopic particles without membrane .
22) GOLGI BODY is formed of stacked Cisternae with swollen ends , vacuoles and vesicles .
23) LYSOSOMES are electron-microscopic single membrane bound vasicular structure of animals cells and contain hydrolytic enzymes .
24) MITOCHONDRIA are rod-shaped , double-membranous , light-microscopic , eukaryotics structures . Inner membrane is with cristea and oxysomes .
25) PLASTIDS are largest sized eukaryotic structures of plant cells . They have their own DNA and ribosomes . These are of three types :- 1) LEUCOPLAST 2) CHLOROPLASTS 3) CHROMOPLASTS .
26) CENTROSOMES is present in animal cell . It is formed of two microtubular centrioles each being formed of 9 triplet microtubules showing 9 + 0 arrangement .
27) CENTRAL VACUOLES of some plants cells may occupy 50 - 90 % of cell volume .
28) CYCLOSIS :- Streaming movement of cytoplasm .
29) AUTOPHAGY :- Digestion of its own cell organelles or reserve food by the lysosomes .
30) TONOPLAST :- Vacuolar membrane present around the cell sap .
31) CAMILLO GOLGI discovered Golgi bodies and shared Nobel Prize in 1906 with SANTIAGO RAMONY CAJAL for their work on nervous system .
32) In man , the number of cells is estimated to be 100 trillion (10¹⁴) .
2) Each living cell has capacity to perform certain basic functions which are characteristics of life .
3) ROBERT HOOKE ( 1665 ) first discovered the cell . He coined the term cell .
4) A.V. LEEUWENHOEK ( 1831 ) first studied the living cell .
5) ROBERT BROWN ( 1839 ) and SCHWANN ( 1839 ) proposed cell theory . It states .
* All plants and animals are made up of cells .
* Cell is basic unit of life .
* R. VIRCHOW ( 1885 ) suggested all cells arise from pre-existing cells .
6) Cells vary in number , shape and size not only in different organisms , but also in various parts of Same body .
7) Cells are enclosed by plasma membrane formed of lipid and proteins .
8) Plasma membrane is flexible and semipermeable - It regulates the flow of material into and out of cell .
9) The diffusion of water , solvent through a semipermeable membrane from a region of higher concentration to a region of lower concentration is called OSMOSIS .
10) In plant cell , a freely permeable cell wall formed of cellulose is present outside plasma membrane . It is protective and supportive layer .
11) The presence of freely permeable cell wall enables the cells of plants , fungi , and bacteria to exist in hypotonic media without bursting .
12) A true Nucleus is present . It is generally single - Spherical and central in position .
13) Nucleus is separated from the cytoplasm by a double layered membrane called NUCLEAR MEMBRANE .
14) PROTOPLASM . It is the living material of cell . PURKINJE coined the term Protoplasm .
15) HUXLEY regarded protoplasm as the PHYSICAL BASIC OF LIFE .
16) CYTOPLASM is the fluid content of cell present between nucleus and plasma membrane . It contains METABOLITES and ORGANELLES .
17) Cells are two types I.e. PROKARYOTIC and EUKARYOTIC CELL .
18) PROKARYOTIC CELLS lack well organised nuclear membrane and membrane bound organelles . They have 70 S type of ribosomes .
19) EUKARYOTIC CELLS have proper Nucleus and membrane bound organelles . 80 S ribosomes are present .
20) ENDOPLASMIC RETICULUM is an electron-microscopic interconnected network of membrane bound tubes and sheets called CISTERNAE , TUBELES or VESICLES . It is of two types :- RER ( Cisternae are studded with ribosomes and involved in protein synthesis ) . and
SER ( Tubules are without ribosomes ) .
21) RIBOSOMES are composed of RNA and proteins , granular electron-microscopic particles without membrane .
22) GOLGI BODY is formed of stacked Cisternae with swollen ends , vacuoles and vesicles .
23) LYSOSOMES are electron-microscopic single membrane bound vasicular structure of animals cells and contain hydrolytic enzymes .
24) MITOCHONDRIA are rod-shaped , double-membranous , light-microscopic , eukaryotics structures . Inner membrane is with cristea and oxysomes .
25) PLASTIDS are largest sized eukaryotic structures of plant cells . They have their own DNA and ribosomes . These are of three types :- 1) LEUCOPLAST 2) CHLOROPLASTS 3) CHROMOPLASTS .
26) CENTROSOMES is present in animal cell . It is formed of two microtubular centrioles each being formed of 9 triplet microtubules showing 9 + 0 arrangement .
27) CENTRAL VACUOLES of some plants cells may occupy 50 - 90 % of cell volume .
28) CYCLOSIS :- Streaming movement of cytoplasm .
29) AUTOPHAGY :- Digestion of its own cell organelles or reserve food by the lysosomes .
30) TONOPLAST :- Vacuolar membrane present around the cell sap .
31) CAMILLO GOLGI discovered Golgi bodies and shared Nobel Prize in 1906 with SANTIAGO RAMONY CAJAL for their work on nervous system .
32) In man , the number of cells is estimated to be 100 trillion (10¹⁴) .
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