PROKARYOTES
Bacteria are the sole members of Monera kingdom.
Main characteristics of prokaryotes:-
(1) Cell Wall:-Cell wall of prokaryotes is made up of peptidoglycan(murein) which is a type of mucopeptide.
(2) Cytoplasm:- (A) Like eukaryotes the cell membrane of prokaryotes is made up of lipoprotein {lipid + protein}
(B) The space between cell wall and cell membrane is known as periplasmic space. This space, is analogous to lysosome because in this space that digestion of complex substance is done.
(3) Cytoplasm:- (A) The cytoplasm of prokaryotes lacks membrane bounce cell organelles.
(B) In prokaryotes cell, the nucleus is indistinct. The nucleus of prokaryotes is also known as incipient nucleus,genophore, nucleoid or fibrillar nucleus. Nuclear membrane is absent around nucleus. It also lacks nucleolus.
Prokaryotes also lack the true chromosome. Instead of it, a false chromosome is present, which is made up of ds circular naked DNA + Non histone protein like polyamines. This files chromosome coils and forms the chromosomal region, which is known as nucleoid.
(C) In prokaryotes ribosomes are of 70s type. Ribosome are the site of protein synthesis.
EUBACTERIA :-
HISTORY
1. They were first observed in rainy water and latter in teeth scum by Leeuwenhoek (1675) and called them "Animalcule".
2. F.J. Cohen and Ehrenberg first of all coined the name "Bacteria".
3. Bergey placed bacteria in "Prosophyta group" and wrote a book "Manual of Determinative Bacteriology". This book is known as "Bible of bacterial classification".
SHAPE
Bacteria have variations in their shape. On the basis of their shape bacteria are of different types.
1. Coccus/Coccus -
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👉 These Bacteria are spherical
👉 These are smallest bacteria
👉 Maximum resistant bacteria
eg. Diplococcus pneumoniae
2. Bacillus/Bacillus -
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👉 This group includes most of the bacteria
👉 These are rod shaped
eg. E.coli, Bacillus anthracis
3. Spirillum/Spirilla -
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👉 These are spiral shaped bacteria
eg. Spirillum volutans, Treponema
4. Comma/Vibrio -
👉 These are comma shaped bacteria
eg. Vibrio cholerae
MOTILITY IN BACTERIA
Bacteria are motile as well as non motile. Movement in bacteria takes place by means of flagella.
On the basis of arrangement of flagella (flagellation) bacteria are of following types:-
1. Atrichous - When flagella are absent, it is called atrichous form.
eg. Micrococcus
2. Monotrichous - When only one flagellum on one end of the bacterium.
eg. Vibrio
3. Amphitrichous - When single flagellum is present on both the ends of bacterium.
eg. Nitrosomonas
4. Lophotrichous - When a bunch of flagellum is present on both end of bacterium.
eg. Salmonella
5. Cephalotrichous - When a bunch of flagella is present on one end of bacteria.
eg. Corynebacterium
6. Peritrichous - When flagella are found on the whole body of bacteria.
eg. E.coli., Salmonella typhi
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