Evolution of Cell Theory: From Observations to Modern Understanding

 
CELL THEORY
&
TYPES OF CELLS
undefined
Robert Hooke
 -1665
observed the slices of
cork tissue under
compound microscope
He saw honey comb
like arrangement
composed of small
compartments.
He coined the term
cell
 for individual
units
undefined
Robert Brown
- 1831 observed a
spherical body 
in each cell and
called it as nucleus
undefined
M.J .Schleiden
 and 
Theodore Schwann
concluded that all living tissues-plant and
animals are composed of individual cellular units
and they proposed the 
cell theory
Cell theory states that all organisms are
composed of one or more cell and 
The cell is the structural and functional unit of
the life
 
CELL THEORY
CELL THEORY
undefined
 
Rudolf Virchow
 states that a new cell can arise only by
the division of a pre-existing living cell
The three tenets to the 
cell theory
 are as described
below:
1. 
All living organisms are composed of one or
more 
cells
.
2. The
cell
 is the basic unit of structure and
organization in organisms.
3.
Cells
 arise from pre-existing 
cells
.
THREE TENETS TO THE CELL THEORY  
THREE TENETS TO THE CELL THEORY  
undefined
 
MODERN THEORY- 
MODERN THEORY- 
CELL THEORY
CELL THEORY
 
Energy flow occurs within cells
 
Heredity information (DNA) is
passed on from cell to cell
 
All cells have the same basic
chemical composition
undefined
 
PROTOPLASM THEORY
PROTOPLASM THEORY
 
Proposed by 
Hertwig
 in 1892
It states that the cell contains a
viscous,colourless,translucent,col
loidal susbstance called
protoplasm
Protoplasm means 
first
substance
undefined
 
 
The term protoplasm was
coined by 
Purkinje
 in 1840
Protoplasm is also called
substance of life
, or
physical basis 
of life
undefined
 
Protoplasm shows 
all the
activities
 like metabolism,
movement , growth homeostasis,
reproduction etc
As long as protoplasm carries
metabolic activities it is 
alive.
The moment activities stop,
protoplasm no longer live and
soon 
disintegrates
undefined
 
GERM PLASM THEORY
GERM PLASM THEORY
o
Proposed by 
August Weismann 
in
1892
o
The body of organism is formed
of two types of cells namely
somatic cells 
and 
germ cells
o
Cytoplasm present in the
somatic cells is called
somatoplasm
 and in germ cells is
called 
germplasm
undefined
 
 
Somatoplasm dies with death of
animal
But Germ plasm is carried to the
next generation
The Reproductive cells are said
to be germ cells
undefined
 
ORGANISMAL THEORY
ORGANISMAL THEORY
Proposed by 
Laurence Picken 
in
1960
It states that cell is an organism
Unicellular
 organism is small,
much less differentiated mass of
protoplasm
Multicellular
 organism is large,
highly differentiated mass of
protoplasm
undefined
 
ORGANISMAL THEORY
ORGANISMAL THEORY
It states that cytoplasm of one
cell is connected to the
neighbouring cell by cytoplasmic
strand called 
plasmodesmata
This theory is 
not accepted
because it is applicable only to
plants
 
undefined
 
SHAPE AND SIZE OF CELL
Shape varies depends upon the functional
requirement of organism and environmental
conditions
irregular like amoeba, spherical, cuboidal, spindle,
oval, etc
undefined
 
 
STRUCTURE OF A CELL
 
cell has three
distinct regions
namely 
cell wall,
protoplasm and
vacuole
cell wall and
vacuoles are non-
living components
protoplasm is
differentiated into
nucleus and cytoplasm
nucleus is
surrounded by nuclear
membrane
undefined
 
STRUCTURE OF A CELL
cytoplasm
 is surrounded by cell or plasma
membrane
cytoplasm is differentiated into 
outer
ectoplasm and inner endoplasm
endoplasm encloses various 
cell organelles
main cytoplasmic organelles are
mitochochondria, plastids, golgi complex,
endoplasmic reticulum, ribosomes,
lysosomes, flagella, centroso
undefined
 
undefined
 
STRUCTURE OF A CELL
plant cell has an outermost envelop
called 
cell wall
cell wall
cell wall is absent in animal cell
undefined
 
FUNDAMENTAL PROPERTIES OF CELL
1.
Membrane
Membrane
    A cellular membrane, also called a plasma
    A cellular membrane, also called a plasma
membrane, surrounds all cells. give the cell shape,
membrane, surrounds all cells. give the cell shape,
and to keep the internal components confined and
and to keep the internal components confined and
separate from the extracellular fluid that
separate from the extracellular fluid that
surrounds all cells
surrounds all cells
2.The nucleus serves two main functions. It holds the
2.The nucleus serves two main functions. It holds the
genetic material, known as deoxyribose nucleic
genetic material, known as deoxyribose nucleic
acid or DNA. It also coordinates the activities of
acid or DNA. It also coordinates the activities of
the cell
the cell
3.
 
The cytoplasm serves several important cellular
The cytoplasm serves several important cellular
functions. cytoplasm provides cells with shape.
functions. cytoplasm provides cells with shape.
The cytoplasm dissolves cellular waste products. It
The cytoplasm dissolves cellular waste products. It
also facilitates movement and conducts electricity.
also facilitates movement and conducts electricity.
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Robert Hooke and Robert Brown made key observations leading to the cell theory, while M.J. Schleiden, Theodore Schwann, and Rudolf Virchow developed the foundational principles. The modern cell theory expanded to include energy flow, heredity, and cell composition. Protoplasm theory highlighted the significance of protoplasm in cellular activities, ultimately defining the essence of life at the cellular level.


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  1. CELL THEORY & TYPES OF CELLS

  2. Robert Hooke -1665 observed the slices of cork tissue under compound microscope He saw honey comb like arrangement composed of small compartments. He coined the term cell for individual units

  3. Robert Brown- 1831 observed a spherical body in each cell and called it as nucleus

  4. CELL THEORY M.J .Schleiden and Theodore Schwann concluded that all living tissues-plant and animals are composed of individual cellular units and they proposed the cell theory Cell theory states that all organisms are composed of one or more cell and The cell is the structural and functional unit of the life

  5. THREE TENETS TO THE CELL THEORY Rudolf Virchow states that a new cell can arise only by the division of a pre-existing living cell The three tenets to the cell theory are as described below: 1. All living organisms are composed of one or more cells. 2. Thecell is the basic unit of structure and organization in organisms. 3.Cells arise from pre-existing cells.

  6. MODERN THEORY- CELL THEORY Energy flow occurs within cells Heredity information (DNA) is passed on from cell to cell All cells have the same basic chemical composition

  7. PROTOPLASM THEORY Proposed by Hertwig in 1892 It states that the cell contains a viscous,colourless,translucent,col loidal susbstance called protoplasm Protoplasm means first substance

  8. The term protoplasm was coined by Purkinje in 1840 Protoplasm is also called substance of life, or physical basis of life

  9. Protoplasm shows all the activities like metabolism, movement , growth homeostasis, reproduction etc As long as protoplasm carries metabolic activities it is alive. The moment activities stop, protoplasm no longer live and soon disintegrates

  10. GERM PLASM THEORY oProposed by August Weismann in 1892 oThe body of organism is formed of two types of cells namely somatic cells and germ cells oCytoplasm present in the somatic cells is called somatoplasm and in germ cells is called germplasm

  11. Somatoplasm dies with death of animal But Germ plasm is carried to the next generation The Reproductive cells are said to be germ cells

  12. ORGANISMAL THEORY Proposed by Laurence Picken in 1960 It states that cell is an organism Unicellular organism is small, much less differentiated mass of protoplasm Multicellular organism is large, highly differentiated mass of protoplasm

  13. ORGANISMAL THEORY It states that cytoplasm of one cell is connected to the neighbouring cell by cytoplasmic strand called plasmodesmata This theory is not accepted because it is applicable only to plants

  14. SHAPE AND SIZE OF CELL Shape varies depends upon the functional requirement of organism and environmental conditions irregular like amoeba, spherical, cuboidal, spindle, oval, etc

  15. STRUCTURE OF A CELL cell has three distinct regions namely cell wall, protoplasm and vacuole cell wall and vacuoles are non- living components protoplasm is differentiated into nucleus and cytoplasm nucleus is surrounded by nuclear membrane

  16. STRUCTURE OF A CELL cytoplasm is surrounded by cell or plasma membrane cytoplasm is differentiated into outer ectoplasm and inner endoplasm endoplasm encloses various cell organelles main cytoplasmic organelles are mitochochondria, plastids, golgi complex, endoplasmic reticulum, ribosomes, lysosomes, flagella, centroso

  17. STRUCTURE OF A CELL plant cell has an outermost envelop called cell wall cell wall is absent in animal cell

  18. FUNDAMENTAL PROPERTIES OF CELL 1.Membrane A cellular membrane, also called a plasma membrane, surrounds all cells. give the cell shape, and to keep the internal components confined and separate from the extracellular fluid that surrounds all cells 2.The nucleus serves two main functions. It holds the genetic material, known as deoxyribose nucleic acid or DNA. It also coordinates the activities of the cell 3.The cytoplasm serves several important cellular functions. cytoplasm provides cells with shape. The cytoplasm dissolves cellular waste products. It also facilitates movement and conducts electricity.

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