Cell
Structure &
Function
Topics covered:
Cell Anatomy and Morphology
Membrane Transport
Cellular Organisation
,Cell Structure &
Function
Cell Biology
Cell is a unit of structure and biological activity made of an organized mass of protoplasm
surrounded by a protective and selectively permeable covering cell biology is the study of all
aspects cells and their components including their structure, biochemistry, development
and physiology.
Discovery of Cell
All organisms are made of one or more cells, cell are the basic unit of structure and function
of organisms. It was discovered by Robert Hooke (1665). When he saw empty compartments
in a very thin slice of cork under his microscope. He wrote a book Micro Graphia and coined
the term cell. The initial idea of cell theory was given by a French biologist Dutro Chat
(1824).
Cell Theory
In 1838. M.J. Schleiden found that all plant cells have essentially similar structure
T. Schwan (1838) working independently observed that animal cells don’t have cell wall but
are otherwise similar amongst themselves. He put forward cell hypothesis bodies of animals
and plants are made-up of cells. Schleiden and Schwann (1839) compared their findings and
formulated cell theory.
Who clearly outlined the basic features of cell theory that states.
Living beings are made of cells and their products. Depending upon the number of
cells, a living being is unicellular, colonial, or multicellular.
A cell is a mass of protoplasm having a nucleus.
Cells are similar in basic structure and metabolism.
The function of an organism is due to activities and interactions of its cell.
Cell theory was further modified in the light of Virchows finding (1855, 1858) that cells
develop from pre-existing cells- 'Omnis cellula - e' cellula'. It is known as law of cell
lineage. (Cell Principle or doctrine of cell). Later on, a number of the other modifications
were carried out in the cell theory. The modern cell theory is called cell principle on doctrine
of cell.
,1. He found that all living cells arise from pre-existing cells (ominis cellulae cellula).
2. The old theory was thus revised and the mod ern cell theory proposed as follows,
I. All living organisms are made up of cells
II. Cells always arise from the pre-existing living cells by division.
III. Every organism starts its life from a single cell.
IV. The growth of the organism is due to the growth of the cells or due to cell
multiplication.
3. Viruses do not fit in the definition of cell-para-mecium a protozoan, Rhizopus a fungus
and Wuchereria an alga is also regarded as the exception to the cell theory.
4. The cells require a constant flow of energy for maintaining their structure and function.
This energy is obtained by photosynthesis or by chemical bonds in the food molecules.
Organism Theory
Sachs (1874) proposed that the whole organism functions as a single entity which is made of
a continuous mass of protoplasm incompletely divided into cells.
Cellular totipotency and survival
Some nucleated cells are totipotent or able to pro- duce to complete organism, especially so
in case of plant cells Skoog and Miller (1957), succeeded inducing morphogenesis in callus,
while Steward et al (1957) established the concept of cellular totipotency. They were able to
form complete plant from Isolated cell.
Regulation of cellular activities
Flow of Energy: Each cell requires In Flow of energy for performing various Physical,
Chemical, and biological activities basically overcoming Tendency to entropy (disorder-
ness). Photosynthetic cells possess chloroplasts for absorbing light energy, Converting the
since into Chemical energy and storing the Some as food energy. Photosynthetic cells are,
therefore, called 'Energy transducers' food energy becomes available to both Photosynthetic
and non-Photosynthetic cells.
Flow of Information: It is required for performing specific Functions at Particular times,
Information is of two types.
Intrinsic (Internal) and extrinsic (External) Through nerves and hormones, Intrinsic for
genetic information is contained in DNA, Specific triggers activate DNA segments to
, transcribe MRNAS which then help synthesis specific polypeptides/proteins/ enzymes etc.
Stimulated nerves Secrete Chemicals to activate Certain cells. Hormones a are Chemical
messengers produced by endocrine or ductless glands. Information molecule act in three
ways.
Membrane Receptor: Information molecule combines with membrane receptor and
activate CAMP to perform on particular Function.
Membrane Permeability: Information molecule changes permeability of cells that
allows entry and exit of specific chemicals
Genetic controls: Information molecule passes into cell Interior and, reaches the
nucleus to sup- press for activate certain genes.
Shape and Size of cells
Shape: Cells of animals and, plants are in a wide range of shapes, the Shape is varied and, it
depends upon the environmental conditions, Surroundings, Functions and needs of the
organism.
The examples of the cells are simple bacteria, which came be rod shaped, Spiral oval,
round, etc. The shapes of desmids and diatoms are varied.
Amoeba and leucocytes keep on changes their shapes the lardy of unicellular marine
algae. Acetabularia is, an exceptional reach a sized about of 10 cm, as differentiated
into rhizoid life busy along the slender stalk and on umbrella life cap. The RBCs of
human beings are round, whereas the muscle cells are along and sharp pointed ends.
Animal cells are capable of changing their shapes, but the shapes of plant cell are iced
due to the presences of cellulose in cell wall.
Size: The size of cells also varies considerably in the animal and plants kingdom. The
diameter of most of the cells ranges from 0.5 u to 20 u (1 u = 0.001 mm). The smallest cell
observed so for is the PPLO (Pleuro pneumonia like organism) about one micro in
diameter It is not visible under ordinary light microscope. The eggs of Insects are quite large.
But the largest known cell is the eggs of an ostrich which considered.
Cell number: The cell number varies to a large extent some organisms are small and
unicellular while other are giants and multicellular. Among unicellular forms,
Chlamydomonas, Chlorella, are of common occurrence, while those of multicellular forms
Ulothrix, mosses, terms etc.,
Two Basic cell types: In a broad sense, a cell is differentiated in to the
cytoplasm and nucleus, the former being surrounded by the plasma membrane and, the later
by nuclear membrane (nuclear envelope). Both other surrounded plays be vital role in the
cellular functions, characteristic of life. Based on the presence of an absence of the nuclear
membrane The cells are classified into two types – Eukaryotic and Prokaryotic
Structure &
Function
Topics covered:
Cell Anatomy and Morphology
Membrane Transport
Cellular Organisation
,Cell Structure &
Function
Cell Biology
Cell is a unit of structure and biological activity made of an organized mass of protoplasm
surrounded by a protective and selectively permeable covering cell biology is the study of all
aspects cells and their components including their structure, biochemistry, development
and physiology.
Discovery of Cell
All organisms are made of one or more cells, cell are the basic unit of structure and function
of organisms. It was discovered by Robert Hooke (1665). When he saw empty compartments
in a very thin slice of cork under his microscope. He wrote a book Micro Graphia and coined
the term cell. The initial idea of cell theory was given by a French biologist Dutro Chat
(1824).
Cell Theory
In 1838. M.J. Schleiden found that all plant cells have essentially similar structure
T. Schwan (1838) working independently observed that animal cells don’t have cell wall but
are otherwise similar amongst themselves. He put forward cell hypothesis bodies of animals
and plants are made-up of cells. Schleiden and Schwann (1839) compared their findings and
formulated cell theory.
Who clearly outlined the basic features of cell theory that states.
Living beings are made of cells and their products. Depending upon the number of
cells, a living being is unicellular, colonial, or multicellular.
A cell is a mass of protoplasm having a nucleus.
Cells are similar in basic structure and metabolism.
The function of an organism is due to activities and interactions of its cell.
Cell theory was further modified in the light of Virchows finding (1855, 1858) that cells
develop from pre-existing cells- 'Omnis cellula - e' cellula'. It is known as law of cell
lineage. (Cell Principle or doctrine of cell). Later on, a number of the other modifications
were carried out in the cell theory. The modern cell theory is called cell principle on doctrine
of cell.
,1. He found that all living cells arise from pre-existing cells (ominis cellulae cellula).
2. The old theory was thus revised and the mod ern cell theory proposed as follows,
I. All living organisms are made up of cells
II. Cells always arise from the pre-existing living cells by division.
III. Every organism starts its life from a single cell.
IV. The growth of the organism is due to the growth of the cells or due to cell
multiplication.
3. Viruses do not fit in the definition of cell-para-mecium a protozoan, Rhizopus a fungus
and Wuchereria an alga is also regarded as the exception to the cell theory.
4. The cells require a constant flow of energy for maintaining their structure and function.
This energy is obtained by photosynthesis or by chemical bonds in the food molecules.
Organism Theory
Sachs (1874) proposed that the whole organism functions as a single entity which is made of
a continuous mass of protoplasm incompletely divided into cells.
Cellular totipotency and survival
Some nucleated cells are totipotent or able to pro- duce to complete organism, especially so
in case of plant cells Skoog and Miller (1957), succeeded inducing morphogenesis in callus,
while Steward et al (1957) established the concept of cellular totipotency. They were able to
form complete plant from Isolated cell.
Regulation of cellular activities
Flow of Energy: Each cell requires In Flow of energy for performing various Physical,
Chemical, and biological activities basically overcoming Tendency to entropy (disorder-
ness). Photosynthetic cells possess chloroplasts for absorbing light energy, Converting the
since into Chemical energy and storing the Some as food energy. Photosynthetic cells are,
therefore, called 'Energy transducers' food energy becomes available to both Photosynthetic
and non-Photosynthetic cells.
Flow of Information: It is required for performing specific Functions at Particular times,
Information is of two types.
Intrinsic (Internal) and extrinsic (External) Through nerves and hormones, Intrinsic for
genetic information is contained in DNA, Specific triggers activate DNA segments to
, transcribe MRNAS which then help synthesis specific polypeptides/proteins/ enzymes etc.
Stimulated nerves Secrete Chemicals to activate Certain cells. Hormones a are Chemical
messengers produced by endocrine or ductless glands. Information molecule act in three
ways.
Membrane Receptor: Information molecule combines with membrane receptor and
activate CAMP to perform on particular Function.
Membrane Permeability: Information molecule changes permeability of cells that
allows entry and exit of specific chemicals
Genetic controls: Information molecule passes into cell Interior and, reaches the
nucleus to sup- press for activate certain genes.
Shape and Size of cells
Shape: Cells of animals and, plants are in a wide range of shapes, the Shape is varied and, it
depends upon the environmental conditions, Surroundings, Functions and needs of the
organism.
The examples of the cells are simple bacteria, which came be rod shaped, Spiral oval,
round, etc. The shapes of desmids and diatoms are varied.
Amoeba and leucocytes keep on changes their shapes the lardy of unicellular marine
algae. Acetabularia is, an exceptional reach a sized about of 10 cm, as differentiated
into rhizoid life busy along the slender stalk and on umbrella life cap. The RBCs of
human beings are round, whereas the muscle cells are along and sharp pointed ends.
Animal cells are capable of changing their shapes, but the shapes of plant cell are iced
due to the presences of cellulose in cell wall.
Size: The size of cells also varies considerably in the animal and plants kingdom. The
diameter of most of the cells ranges from 0.5 u to 20 u (1 u = 0.001 mm). The smallest cell
observed so for is the PPLO (Pleuro pneumonia like organism) about one micro in
diameter It is not visible under ordinary light microscope. The eggs of Insects are quite large.
But the largest known cell is the eggs of an ostrich which considered.
Cell number: The cell number varies to a large extent some organisms are small and
unicellular while other are giants and multicellular. Among unicellular forms,
Chlamydomonas, Chlorella, are of common occurrence, while those of multicellular forms
Ulothrix, mosses, terms etc.,
Two Basic cell types: In a broad sense, a cell is differentiated in to the
cytoplasm and nucleus, the former being surrounded by the plasma membrane and, the later
by nuclear membrane (nuclear envelope). Both other surrounded plays be vital role in the
cellular functions, characteristic of life. Based on the presence of an absence of the nuclear
membrane The cells are classified into two types – Eukaryotic and Prokaryotic
