14 |
A Handbook of Biology
It divides the kingdom monera into two domains, leaving the remaining 4
eukaryotic kingdoms in the third domain.
KÏÑGDØM MØÑËRÅ
Bacteria are the most abundant microorganisms.
Hundreds of bacteria are present in a handful of soil.
They also live in extreme habitats such as hot springs, deserts, snow &
deep oceans. Many are parasites.
Based on shape, bacteria are of 4 types: Coccus (Spherical), Bacillus
(Rod-shaped), Vibrium (Comma-shaped) & Spirillum (Spiral).
Some bacteria are autotrophic (synthesize food from inorganic
substrates). Majority are heterotrophs (they do not synthesize food but
depend on other organisms or on dead organic matter for food).
Monera has 2 major group - Archaebacteria and Eubacteria.
ÅRÇHÅËBÅÇTËRÏÅ
They live in the most harsh habitats such as extreme salty areas
(halophiles), hot springs (thermoacidophiles) and marshy areas
(methanogens). (Odisha NEET 2019)
Archaebacteria have a different cell wall structure for their survival in
extreme conditions
Methanogens are present in the guts of ruminant animals (cows,
buffaloes, etc). (NEET-II 2016)
They produce methane (biogas) from the dung of these animals.
(NEET-I 2016)
Halophiles
and
methanogens
are
obligate
anaerobes
while
thermoacidophiles are facultative anaerobes.
ËÜBÅÇTËRÏÅ (’TRÜË BÅÇTËRÏÅ’)
They have a rigid cell wall and a flagellum (if motile).
They include Autotrophs (photosynthetic and chemosynthetic) and
Heterotrophs.
Term bacteria was given by Ehrenburg.
‘Germ Theory of disease’ was given by Louis Pasteur.
Father of bacteriology-Anton von Leeuwenhoek