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Cell Biology

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General Information
Cell Biology: Structure and function of cells and intracellular organelles (of
both prokaryotes and eukaryotes): mechanism of cell division including (mitosis
and meiosis) and cell differentiation: Cell-cell interaction; Malignant growth;
Immune response: Dosage compensation and mechanism of sex determination
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Resolving Power: Ability to distinguish two close points as two separate
points by any optical system is called as its resolving power
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Mathematically, resolving power = l2
where l is the source of illumination
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3 microns & 10 Å respectively
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Zacharis Janssens combined lenses in an effort to improve magnifying
efficiency and resolving power
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3
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He believed that the plants are composed of separate
structural units 

which he called “utricles”
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He saw hundreds of very small
hexagonal ‘boxes’ or ‘chambers’ which are together appeared like a
‘honeycomb’
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His observations, alongwith the figures, were published
in 1665 in Micrographia
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In this way, he was the first to observe
“living and moving individual” cells as compared to the “fixed” cells
seen by earlier workers
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J
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He expressed the idea of
individual cells i
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, cells were not just spaces between a network of
fibres, but that these were separate and separable units
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Concept of Protoplasm :

Corti (1772) first of all observed that all cells contain a living substance
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Felix Dujardin (1836), observed it in living
amoebae, and called it ‘Sarcode’
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E
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Hugo von Mohl (1846), also suggested the
same name – protoplasm – for the similar substance found in plant cells
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It is now, therefore, known as Brownian movement
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He used the word ‘nucleus’ to identify them
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J
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He stated that –
(a)  living things are composed of cells and cell products
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In fact, Schwann coined the word “metabolism” for all chemical processes carried
on in the cell
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Rudolf Virchow (1858), a German pathologist, developed the idea of generation
to generation continuity of cell that Omnis cellula e cellula (i
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cells arise from
pre- existing cells)
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Nucleolus: In 1781, Fontana had seen dense spherical body inside nucleus
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But, it was given the name “nucleolus” by
Bowman (1840)
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Overton (1899) proved its existence
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Q
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Protoplasm Theory : Max Schultze (1861) proposed the protoplasm theory
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Plastids : N
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Sachs (1865-1892) described coloured bodies
in the cytoplasm which were called plastid by Haeckel in 1866
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The green
plastids were also identified by Meyer (1883) who called them autoplasts
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Mitochondria : Kollicker (1880) was the first to observe small thread-like
structures in the cytoplasm of the striated muscle cells of insect
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Altmann (1890) described them as “bioplasts”
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Centrosome : Boveri (1888) used the word “centrosome” for a body found at one
pole of the cell near the nucleus in animal cells
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Various theories about
the nature of protoplasm are:

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(b)  Fibrillar theory of Velton;


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(d)  Colloidal theory of Fischer;


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(f)  sol-gel theory of Hyman
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But colloidal theory of Fischer is best
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20
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22
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e
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23
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9 ± 0
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4 ± 0
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34 ± 0
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This
increases their surface area
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Dutrochet (1824) gave the
idea of individuality of cells
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cella = hollow space) coined by Hooke (1665) is misnomer as
cell is not a hollow structure
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Leeuwenhoek (1672) was first to see a free cell
under microscope and called them tiny animalcules
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(a)  Haberlandt (1902) suggested the idea of tissue culture
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(b)  Steward et al (1957) provided first evidence of cellular
totipotency by growing 

mature problem tissue of carrot roots in a medium supplemented
with coconut 

milk
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(c)  Tissue culture was raised by White (1932) when he grew
tomato roots on artificial 

medium
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(d)  Callus by White, Gauthret and Nobecourt
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(e)  Differentiation of Callus into tissues by Skoog and Miller
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(f)  Single cell culture (cellular totipotency) by Steward (1957)
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(g)  Nurse technique to get callus from a single cell by Muir et al (1958)
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(h)  Microchamber technique for single cell culture by Vasil &
Hilderbrandt (1965)
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(i)  Embryoid (non zygotic embryo) culture by Steward et al (1963), Halperin
& Wetherell (1964)
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(j)  Embryo culture by Laibach (1928)
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(k)  Pollen/Haploid androgenic culture from anthers of Dature by Guha & 

Maheshwari (1966)
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Ostrich egg (Largest cell) is 15-20 × 13
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Human nerve cell (Longest animal cell) is 90 cm
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Viruses do not have a cellular structure
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In human beings, cells of kidney are smallest and of nerve fibre longest
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1 to 0
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