PROKARYOTIC CELL STRUCTURE
Living organisms are differentiated from nonliving matter
by their (1) ability to reproduce (2) ability to ingest or assimilate
food and metabolize them for energy and growth (3) ability to
excrete waste products (4) ability to react to changes in their environment
(irritability) and (5) Susceptibility to mutation. The living
organisms include a variety of micro and macro organisms of
differing size , shape morphology, and behaviour. They include
tiny bacteria, protozoans, worms, plants and animals like man,
whale and elephants.
Carlous Linnaeus (1707-1778), the Swedish botanist was the
first to introduce nomenclature for plants and animals. Until 18th
century only plant and animal kingdoms were recognized. However
some organisms are predominately plant like, some animal
like and some do not fall in both the groups. Therefore it was felt
a third kingdom was necessary. Haeckel (1866), a German zoologist
suggested a third kingdom Protista to include those organisms
that are not typically plants and animals. Bacteria, algae, fungi and
protozoa are cellular organisms placed under protista. Viruses are
not cellular organisms and therefore not classified as protists. Bacteria
were lower protists while algae, fungi and protozoa were
higher protists. A satisfactory criteria to differentiate bacteria, fungi
and algae could not be made until the development of electron
microscope, which depicted the internal structure of these organisms.
The absence of membrane bound internal structures in bacteria
and their presence in fungi, algae, protozoa, plants and animal
cells was taken as criterion to differentiate prokaryote and
eukaryote
PROKARYOTIC CELL STRUCTURELiving organisms are differentiated from nonliving matterby their (1) ability to reproduce (2) ability to ingest or assimilatefood and metabolize them for energy and growth (3) ability toexcrete waste products (4) ability to react to changes in their environment(irritability) and (5) Susceptibility to mutation. The livingorganisms include a variety of micro and macro organisms ofdiffering size , shape morphology, and behaviour. They includetiny bacteria, protozoans, worms, plants and animals like man,whale and elephants.Carlous Linnaeus (1707-1778), the Swedish botanist was thefirst to introduce nomenclature for plants and animals. Until 18thcentury only plant and animal kingdoms were recognized. Howeversome organisms are predominately plant like, some animallike and some do not fall in both the groups. Therefore it was felta third kingdom was necessary. Haeckel (1866), a German zoologistsuggested a third kingdom Protista to include those organismsthat are not typically plants and animals. Bacteria, algae, fungi andprotozoa are cellular organisms placed under protista. Viruses arenot cellular organisms and therefore not classified as protists. Bacteriawere lower protists while algae, fungi and protozoa werehigher protists. A satisfactory criteria to differentiate bacteria, fungiand algae could not be made until the development of electronmicroscope, which depicted the internal structure of these organisms.The absence of membrane bound internal structures in bacteria
and their presence in fungi, algae, protozoa, plants and animal
cells was taken as criterion to differentiate prokaryote and
eukaryote
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