The document summarizes the must biology topic of cells-the structural and functional unit of life. It contains its organelles and their functions, special facts, its history, animal cell and plant cell, cell theory and a sophisticated mind map for the perfect revision.
TEST BANK FOR CELL BIOLOGY, 3RD EDITION, THOMAS POLLARD, WILLIAM EARNSHAW, JENNIFER LIPPINCOTT-SCHWARTZ, GRAHAM JOHNSON
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All living organisms are composed of cells.
A cell is the structural and functional unit of all living organisms.
Cytology is the study of structure and composition of cell.
Cell biology is a common term used for studying cell at cellular and molecular levels.
Scientists and their contributions in the field of cell biology
Cell [In Greek- Kylos= cell, In Latin -Cella hollow =
space]. The term 'cell' was put
forth by the English microscopist Robert Hooke in 1655.
Robert Brown (1831) discovered a small rounded body within the cell of orchid roots.
He later named it as nucleus.
Antony Van Leeuwenhock (1674) was the first person to observe free cells, bacteria,
protozoa, RBCs and sperms using a home-made microscope. He made microscopes with
the magnification upto 300 X.
Robert Hooke (1665) made many compound microscopes. He examined a thin slice of
dried cork and found them resembling the compartments of a honeycomb. He named the
compartments as "Cels.
Botanist, Matthias Schleiden, and Zoologist, Theodar Schwann, propounded the cell
theory (1838-39).
A German
Physiologist,Rudolf Virchow (1858), added a third aspect to the cell theory
that all cells arise from pre existing cells. (Ominiscellulaecellula)
Viuses are an exception to the cell theory. They are smaller and acellular.
Louis Pasteur demonstrated that life is formed from pre-existing cells.
Cell Theory
Cell is the structural and functional unit of all living beings.
All living organisms are composed of cells.
New cells originate only from pre-existingcells.
The function of an organism as a whole is the outcome ofthe combined activities and
interactions of the constituent cels.
Basic properties of cells
They are highly complex and organized.
Cells have disciplined regulation.
They can multiply and can produce more of their type.
Cells generate and require eFergy.
They cary outmany biochemical reactions.
Cells respond to stimuli.
Cell facts
Single largest cell in the world: Ostrich Egg
Smallest cell: Mycoplasm
Largest human cel: Female ovum
, Smallest human cell: Red blood cell
Longest cell in animals: Nerve cell (Neuron)
Cells generally remain small because small size offers a larger surface area which
facilitates exchange of respiratory gases, intake of nutrients, and removal of wastes
from the cell by diffusion.
Biologically, all organisms are of two types: Prokaryotie and Eukaryotic. This
classification is based on the following factors:
Organization of cell organelles
Variety of cell organelles
Complexity of nuclear material
Difference between plant and animal cells
FEATURESs ANIMAL CELL PLANT CELL
Size & shape Usually much smaller than Comparatively larger in size over 100 um
100 um and vary in shape long and rigid in shape.
Cell wall is absent. Cell is In addition to plasma membrane rigid
Cell wall enclosed in thin flexible thick cell wall is present. It is made up
plasma membrane only. of cellulose.
Cytoplasm Denser and more granular. Less denser.
Nucleus Generally located in centre. | Generally pushed one side by sap vacuole.
Vacuoles are either absent The vacuoles are well-developed. In a
Vacuoles or if present are small in mature plant cell, usually a single large
size and scattered. central sap vacuole is present.
Mitochondria| Numerous. Fewer.
Golgi bodies are well The components of golgi bodies are
Golgi developed and present diffused in the plant and are called
near nucleus. dictyosomes.
Plastids Plastidsare
chlorophyl.
absent. So is the Plastids are present. They contain
chlorophyll.
entrosome and centrioles Centrosome and centrioles are absent,
Centrosome instead polar caps are present.
are present.
Chromosomes Small. Large
Storage of stores reserve Stores reserve carbohydrates as starch.
reserve food carbohydrates as glycogen.
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