MONERA:
[PROKARYOTA]
Coined
by: Ernst Haeckel (1866)
ARCHEBACTERIA:
1. Group of highly primitive Prokaryotes (Oldest
of the Living Fossils). Gram +ve, mostly Non Motile.
2.
Cell Wall made of Non Cellulosic polysaccharides
& proteins (Not Peptidoglycans as in eubacteria)
3. Cell wall contains branched chain lipids
(cause for high tolerance of heat & pH)
TYPES: 1. Methanogens: Anaerobic,produce CH4 from Formic acid & CO2,
eg: Methanococcus; Methanobacterium
Click here for link:-( Methanogen)
2. Halophiles: Live in Saline conditions,trap solar energy by purple
pigmented membrane to produce ATP & not for synthesis of food. Eg; Halococcus;Halobacterium
Click here for link:-(Halophile)
3. Thermoacidophiles: Found in Hot Sulphur Springs,(800 C),Aerobic
microbes,oxidize sulphur to sulphuric acid; under anaerobic conditions some can
reduce Sulphur to H2S. eg;Pyrococcus, Thermoplasma
Click here for link:- ( Thermophile )
EUBACTERIA: Observed firstly by A V Leeuwenhoek
(1675); termed Bacteria by Ehrenberg (1838)
1. SIZE: 20-100A0 to 700-800A0. Largest is
Thiomargarita namibiensis (1000-3000A0)
2. SHAPE: Coccus;
Bacillus; Spirillum; Vibrio
3. FLAGELLUM (9+0) may be
present or absent.
4. Minute hair like
protenicious structures on the surface (FIMBRIAE or PILI)
5. CELL WALL :
Peptidoglycans(amino sugar) & N- acetyl Muremic acid (NAM) containing N-aceryl
glucosamine (NAG) linled together by beta 1-4-linkage. [sometimes diamino
pimilic acid & Teichoic acid also present]
6. MESOSOME (inmany gram +ve
bacteria) as an infolding of cell memberane, functions for Respiration.
7. RESERVE FOOD: Glycogen
& Lipid storesas fat globules & poly-beta-hydroxybuterate.
8. NUTRITION: Autotrophic
(PHOTO:- eg. Green Sulphur bacteria, Rhodospirillum;; CHEMO:- Nitrosomonas & Nitrobactor from Ammonia; Thiobacillus from Sulphur
oxidation) HETEROTROPHIC: Parasitic, Saprotrophic & Symbiotic.
9. REPRODUCTION: ASEXUAL:
Binary Fission / Budding (eg. Rhodomicrobium) Conidia (eg. Streptomyces) Cyst
(eg. Azotobactor) Endospore. SEXUAL: Conjugation /Transformation /Transduction.
10. PLASMID: Extranuclear
circular DNA present in cell.
JUMPING GENES (TRANSPOSONES) ::
Discovered by McClintock (1965)—DNA segments which can move from one
molecule to another and carry resistance for antibiotic Penecillin.
ACTINOMYCETES:--unicellular,branched,filamentous bacteria, similar to
fungal mycelium hence called Mycobacteria.
MYCOPLASMA: simplest & smallest of free Prokaryotes. (PPLO)
Mycoplasma gallisepticum (Smallest living cell) [ Click link here:- Mycoplasma ]
CYANOBACTERIA (Blue green algae):phototrophic prokaryotes, aquatic,
Thallus body . Food is cyanophycean starch & Protien, Reproduction by
fragmentation/akinets/endospores/hormogonia etc..
[ click here:- Cyanobacteria]
SYSTEMS OF CLASIFICATINS:-
Ø
ARTIFICIAL
(ANCIENT SCRIPTS):- also by Pliny the Elder (23-79 AD) and Linnaeus (1737) in
‘Genera Plantarum’.
Ø
NATURAL
SYSTEM:- First by John Ray; also by A.L de Jussiue, A.P de
Candolle. Best explained flowering plants by Bentham & Hooker
(Dicots/Gymnosperms/Monocots) .
Ø
PHYLOGENETIC:
Firstly by Engler & Prantl in “Die
Naturlichen Pflanzen Familien” ,Followed by John
Hutchinson, Takhtajan [ “Taxonomy without Phylogeny is just like bones without
flesh”]
Ø
CLADISTIC
(MODERN PHYLOGENETIC SYSTEM): Given by E.H Willy Henning (1950)- based
on evolutionary history. The Phylogenetic tree is also called Genealogical tree or Dendrogram.
Ø
PHENATIC:
OLDEST METHOD (Theophrastus 4BC) as many characters as possibly visible.
NEW SYSTEMATICS (by Sir
Julian Huxley):
Ø It
includes all the known characteristics of an organism like Genetics, Cytology,
Ecology, Selection theory, Natural History, Paleontology , Physiology etc..
Ø CYTOTAXONOMY:
based on
cellular structure & functions (mostly structure & number of
chromosomes)
Ø NUMERICAL TAXONOMY:
use number algorithm like Cluster analysis( proposed by Sokal &
Sneath,1963) Its application is enhanced with computer technology
(Bioinformatics)
Ø CHEMOTAXONOMY(Biochemical
Systematics by John Griffith Vaughan): comparison of Biochemical compositions,
mostly Proteins, amino acids & peptide bonds. It divides compounds into
Micro- (molecular weight less than 1000eg. Amino acids, fatty acids) &
Macro- molecules (molecular weight greater than 1000 eg. Proteins,
Polysaccharides, DNA).
SYSYEMS OF
CLASIFICATION OF ORGANISMS
TWO
KINGDOM SYSTEM:
(ARISTOTLE) Aristotle
divided livings into:- Plants & Animals. Linnaeus into Animalia &
Vegetabilia. He further divided them into classes. MERIT:- easy & simple.
DEMERITS:- No clear distinction of lower forms into plants & animals,
Position of Euglena (Myxotrophic)/Chlymadomonas (locomotion by flagella;
chloroplast)/ fungus (heterotrophic, cell wall)/Sponges (sessile animals)/Protozoa,
diatoms..lichens.etc..
THREE
KINGDOM SYSTEM(Ernst
Haeckel) added PROTISTA
(all unicellular eg. Bacteria, protozoa, algae, slime moulds etc..)
FOUR
KINGDOM SYSTEM: E. Catton distinguished between Pro-/Eukaryotes. H. Copeland created
fourth kingdom: Prokaryota (now called Monera).
FIVE
KINGDOM SYSTEM: (Robert
Harding Whittaker;1920-1980) Basis of
classification: 1. Complexity/ structure of cell. 2. Complexity of body
organization. 3. Mode of nutrition. 4. Major ecological role. DEMRITS: Protista as mixed bag,
unicellular cases like yeast & Chlymadomonas not included, position of symbiotic
forms like lichen is ambiguous etc..
SIX
KINGDOM SYSTEM:
(Karl Wose-O. Kandler – M.L. Wheelis; 1990) Three major gps. (DOMAIN)- Eukarya (Protista, Fungi,
Plantae, Animalia) Bacteria (Eubacteria) & Archaea (Archebacteria). (based
on recent DNA sequencing & Nucleic acid Hybridization method). Evidence
from experiments of Carol Bult (1996) by sequencing of 1.7 million bp of
bacterium Methanococcus jannaschii.
VIRUSES
Firstly used by Fred Cohen(1984) for
COMPUTER reference, Discovered in Tobacco leaf by D. Ivanowsky.
Adolf Mayer (1879) firstly
transmitted it using juice extract to infect other plants.
M. Beijerinck (1898) called it as
“contagium vivum fluidum”. (soluble living germs)
“VIRION” (simplest structured
viruse) was termed by Lwoff, Anderson & Jacob (1959).
Felix D’Herelle (1917) coined the
term ‘BACTERIOPHAGE’.
W.M.Stanley (1935) purified &
crystallized TMV (Nobel Prize 1946). H. Ruska (1940) photographed Viruse
Harshey & Chase (1952) T-2
Bacteriophage experiments on DNA Semi-conservative replication.
Zinder & Lederberg(1952)
discovered “Generalized Transduction”.
Alick Issacs & Jean Lindemann
(1957) discovered INTERFERONS.
Bruce Samuel Blumberg (1963)
discovered Hepatitis B Virus (Nobel Prize 1976)
Temin & Baltimore (1970)
discovered Reverse Transcription in Retroviruses (Nobel Prize 1975).
T. O Diener (1971) discovered
VIROIDS & differentiated with Viruses.
M Bishop & H Varmus (1976)
explained ONCOGENE from Rous sarcoma Virus (Noble Prize, 1989).
F. Sanger (1977) explained complete
nucleotide sequence of 5375 nucleotides of φx174 (Noble
Prize,1980)
Francosise Barre-Sinoussi and Luc
Montagnier (1983-84) isolated & identified the Human Immunodeficiency Virus
(HIV) that cause Acquired Immuno Deficiency Syndrome (AIDS) [Nobel Prize,
2008].
Yuan Chang & Patrick Moore
(1994) identified Human Herpes Virus 8 (HHV-8), the causative agent of Kaposi’s
Sarcoma using PCR (Polymerase Chain Reaction) Technology.
(courtesy clipartof.com)
Ø CHARACTERISTICS
OF VIRUSES: - Smallest living structures made only of Nucleic acid &
Protein coat. Largest viruses T4 – phages contain 77 genes, smallest Qβ and MS2 contain only 3 genes.
Species specific for host.
Ø STRUCTURE: -
(a) CORE: - genetic material DNA or RNA {* Human Cytomegalo Virus,
exceptionally has BOTH – DNA genome & 4 mRNA’s} (b) CAPSID: - Protective
Protein coat around core (c) NUCLEOCAPSID: - combined structure formed by core
& capsid (d) ENVELOP: - viruses like HIV & Influenza have an additional
lipoprotein layer around capsid derived from cell surface membrane of the Host.
(e) CAPSOMERE: - identical repeating sub- units in some Capsids.
Ø Unlike other
microbes, Viruses do not grow on artificial medium, lacked functional anatomy
& can pass through bacteria proof Chamberland filter (porcelain filter).
Ø Virus undergo
Mutation but act as living only inside a living host ( needed for their
metabolism).
Ø PLAQUES are
clear spots on the surface of culture medium having Bacteriophages &
bacteria, formed by the lyses of host bacterial cells by Bacteriophages.
Ø Viral
reproductive cycle can be LYTIC or LYSOGENIC. In Lytic, virus destroy the host
cell & in Lysogenic, viral genome replicate with host DNA & at times
carry host DNA as PROPHAGES (bacterial Transduction).
Ø CLASSIFICATION:
- Holmes (1948) classified them into Three Groups. I – PHAGINAE (attacks
bacteria), II – PHYTOPHAGENIA (attacks plants) & III _ ZOOPHAGENIA (attacks
animals).
Ø Tobacco Mosaic
Virus (TMV): - discovered by M.W Beijerinck (1898): - First virus discovered,
most studied plant virus, genetic material is ssRNA, Rod shaped, Capsid is made
of 2130 capsomeres each containing single polypeptide chain made of 158 amino
acids.
Ø BACTERIOPHAGES:
- Discovered by Fredrich Twort (1915) & Felix d’Herelle (1917) named it. It
contains Nucleoprotein. Some phages are comma shaped, some spherical but
majority of them are Tadpole shaped. Typically they have a Polyhedral Head,
Short neck, a collar & straight tail. The genetic material DNA is located
in the head enclosed by a protein Capsid.
Ø RETROVIRUSES:
- possess ssRNA genome, also a gene for Reverse Transcription to copy +RNA from
a –DNA copy. (Temin, 1970). Cancer producing viruses are called Oncoviruses.
(General Structure of a Retrovirus)
Ø “Regressive
Theory” of Viral Origin: - origin as mobile genetic elements (like Transposons
or plasmids).
SUB-VIRAL
AGENTS: -
“Non cellular
organisms containing genome but lacks one of the essential features of a virus.”
1.
VIROIDS (discovered by T. O Diener,
1971) small single stranded circular “ Naked RNA” molecules (250-370 nucleotides) without capsid, only
1/10th the size of smallest Virus. Cause disease like Potato
spindle-tuber disease, exocortis disease of citrus trees & chrysanthemum
stunt disease.
2.
SATELLITE VIRUSES (discovered by B.
Kassanis, 1966) known as “Incomplete Viruses”. The replication of these viruses
depends on the co-infection of a second ‘Helper virus’.
3.
VIRUSOIDS (discovered by J.W.
Randles, 1981) structurally & functionally similar to viroids but are
located inside the protein coat of a true virus.
4.
PRIONS (Proteinaceous Infectious
Particles) unique among infectious agents as they contain NO Nucleic Acid
(composed exclusively of Proteins). It does not replicate itself, it causes
another protein to change its shape and thereby becomes a prion (Stanley
Prusiner, awarded Nobel Prize 1997, for his work on prions)
INTERFERONS: (DISCOVERED BY Alick
Isaacs & Jean Lindemann, 1957) group of small antiviral glycoprotein which
inhibit viral multiplication. Human Interferons are of three molecular types: -
(a) alpha Interferon (α-IFN) produced by Leucocytes. (b) Beta Interferon (β-IFN) produced by Fibroblasts and
(c) Gamma Interferon (Ƴ-IFN) produced by Lymphocytes.
Generally, α & β are powerful
Antiviral Protein. Interferons are Virus non-specific (same interferon is
active against different viruses). Apart from defense, they also regulate cell
motility, cell division, activation of Macrophages * Transplant Tissue
rejection (graft rejection).
VIRAL DISEASES OF MAN: -
1.
Pneumotropic Diseases: (involves
respiratory tract) eg. Influenza, SARS & common cold.
2.
Dermotropic Diseases: (involving
Skin & allied structures) eg. Herpes, Chickenpox (Varicella), Smallpox
(Variola), Measles (rubeola), mumps, German Measles (Rubella) etc..
3.
Viscerotropic Diseases: (internal
organs) eg. Yellow fever, Dengue, Hepatitis, AIDS etc..
4.
Neurotropic Diseases: (involves
mainly CNS) eg. Rabies, Polio, Encephalitis.
COMMON PLANT DISEASES BY VIRUSES: -
Bunchy Top of Banana, Grassy
Shoot of Sugarcane, Leaf curl of Papaya, Little leaf of Brinjal, Potato leaf
roll, Rosette disease of Groundnut, Tobacco mosaic, Tobacco ring spot, Tungro
disease of Rice, Yellow vein mosaic of Lady Finger.
PRACTICE EXERCISE:
Ø Which classification is based on morphological character:
artificial/natural/phylogenetic (DPMT 2008).
Ø In Eukaryotes, which of these is not found:
plastid/nucleus/ribosome/mesosome (Har. PMT 2001)
Ø The host of TMV is : Nicotiana/Withania/Triticum/Datura (Odisha JEE
2007)
Ø TMV has a : ssRNA/dsRNA/ssDNA/dsDNA (JKCMEE 2008)
Ø Provirus is: a free virus/primitive virus/free DNA/integral viral
genome (CPMT 2007; JCECE 2008)
Ø Methanogens are most abundant in: Hot springs/Cattle field/sulphur
rock/ polluted stream ( AIPMT 2011)
Ø Infectious proteins are present in: prions/viroids/satellite virus/
Gemini viruses (AIPMT 2010)
Ø Viruses has: prokaryotic nucleus/single chromosome/both DNA &
RNA/DNA in protein coat (AIPMT 2014)
Ø Which one has coiled RNA & capsomeres: Retroviruses/Polio
Virus/Measles Virus/TMV (AIPMT 2014)
Ø Motile bacteria moves by: pili/cilia/flagella/fimbrae (AIPMT 2014)
Ø What perform the function of mitochondria in bacteria: cell
wall/pili/ribosome/mesosome (AIPMT 2014)
Ø Archebacteria differ from eubacteria in: st. of cell
memb./reproduction/nutrition/cell shape (AIPMT 2014)
Ø Which of them is not in Whittaker’s classification: algae/viruses/fungi/bacteria
(BHU 2012)
Ø Cyanobacteria are also referred to as: Protista/golden algae/slime
mould/blue green algae (AIPMT 2012)
Ø Which of them is caused by virus: syphilis/diphtheria/polio/T.B (AMU
2013)
Ø Which of them cause Potato Spindle Tuber disease:
Viroid/virion/prion/Rhabdovirus (MPPMT 2007)
Ø T.O Diener discovered: Bacteriophage/infectious protein/free inf.
RNA/free infectious DNA (AIPMT 2009)
Ø Which of them has ssDNA: TMV/Reovirus/Wound Tumor Virus/φx174 coliphage
(DPMT 2003; Kerala 1997)
Ø Polio is caused by: Bacteriophage/dsDNA virus/ssRNA virus/ssDNA virus
(DUMET 2010)
Ø Phylogenetic system is based up on which of them: floral/chemical/physical/evolutionary
(AIPMT 2009)
Ø Phenatic system is based on: (AIPMT
2003;2004)
(a) Sexual characteristics
(b) Dendrogram based on DNA characteristics
(c) The ancestral lineage of existing organisms
(d)
Observable
characteristics of an existing organism.
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