Biological classification
- Theophrastus wrote many books on 'plants.
Few of them are as follows:
(a) Historia plantarum
(b) Causes of plants
(c) Enquiry into plants
- Theophrastus gave names and descriptions of 480 plants in his book Historia plantarum.
- Theophrastus proposes the first classification of plant kingdom. He classified plant kingdom in to four groups on the basis of growth habit. (a) Trees (b) Shrubs (c) Under shrubs (d) Herbs
3. Carolus Linnaeus: [1707 – 1778]
- He is known as father of taxonomy, father of plant taxonomy and father of animal taxonomy.
- Linnaeus gave the two kingdom system classification. He grouped plants and animals into kingdom plantae and kingdom Anirnalia respectively.
- Linnaeus wrote many books. Some important books are:
(1) Hortus uplandicus - First book
(2) Flora lapponica
(3) Philosophia botanica
(4) Critica botanica
(5) Systema naturae (1737)
(6) Genera plantarum
(7) Species plantarum -last book (1753)
4. A.P. De Candolle:
- He was the first to propose the significance of vascular tissue in taxonomy. On this basis of vascular tissue he classified plants into two groups
(a) Cellular plants (Non vascular plants) - This group includes Thallophyta and Bryophyta
(b) Vascular plants - This group includes Pteridophyta, Gymnosperm and Angiosperms.
5. George Bentham (1800 -1884) and Joseph Dalton Hooker (1817 -1911):
- Both Bentham and Hooker were related to Royal botanical garden.
- They wrote the book "Genera plantarum" (1862 - 1883).
- In this book, Bentham and Hooker gave the biggest and natural classification of spermatophyta i.e. plants with seeds
- In Genera plantarum, there is description of 202 families. In it, basically the description of plants with seeds is present.
6. A. W. Eichler:
- Syllabus de vorlesungen uber phanerogamen kunde - Book written by Eichler.
- In this book, Eichler gave the first phylogenetic classification of plant kingdom.
- The classification of Eichler is very little phylogenetic.
- In this way Eichler classified plant kingdom into five divisions and arranged them in the order of evolution (Phylogeny).
7. Engler (1844 - 1930) & Pranti (1849 - 1893):
- Book - "Die Naturlichen Pflanzen Familien".
- He gave the phylogenetic classification of plant kingdom. This classification was more phylogenetic as compared to Eichler's classification.
8. Oswald Tippo:
- Proposed the biggest phylogenetic classification of plant kingdom.
- This classification is the complete classification of plant kingdom.
- This is the most acceptable classification for books and study.
(a) Cyanophyta:B.G. Alage
(b) Euglenophyta:Euglenoids
(c) Chlorophyta:Green algae
(d) Chrysophyta:Yellow-green algae
(e) Pyrrophyta:Dinoflagellates & Diatoms
(f) Phaeophyta:Brown algae'
(g) Rhodophyta:Red algae
(h) Schizomycophyta:Bacteria
(i) Myxomycophyta:Slime molds (False fungi)
(j) Eumycophyta:True fungi
9. Karl Menz:
- He showed the importance of serology in taxonomy.
- Similarities and dissimilarities in stru. of proteins help to know the phylogenetic relationship of living beings. Living organisms which are phylogenetically close relatives have more similarities in their proteins.
- Organisms which are distantly related have different proteins.
(1) First tissue was originated in animal kingdom in → Coelentrata
(2) First tissues was originated "in plant kingdom in → Bryophyta
(3) Phylogenetic relationship of plants and animals can be established by animal serum. Serology indicates that chimpanzee is closest relative of man.
|
- Haeckel gave the three kingdom (Protista, Plantae, Animalia) system of classification.
- Haeckel established the kingdom Protista.
- Haeckel grouped those living organisms in Protista which did not have tissues.
- Kingdom Protista: Prokaryotes, Protozoa, porifera, Algae & fungi
Five Kingdom Classification (from 1969 to 1990)
In order to develop phylogenetic classification, R.H. Whittaker (1969), an American taxonomist, divided all the organisms into five kingdoms. As the viruses are on the border line of living and nonliving, they have been left out. Whittaker has used five criteria for delimiting the different kingdoms.
1) Complexity of cell structure, prokaryotic and eukaryotic .
2) Complexity of body structure or structural organization, unicellular and multicellular.
3) Mode of nutrition which is divergent in multicellular kingdoms- photoautotrophy in plantae, absorptive heterotrophy in fungi and ingestive heterotropy in animalia. Photoautotrophy totrophic nutrition is also called holophytic nutrition while ingestive heterotrophy is known as holozoic nutrition. Absorptive heterotropy is saprobiotic (=saprophytic ) nutrition.
4) Ecological life style like producers (plantae), decomposers (fungi) and consumers (animalia).
5) Phylogenetic relationships.
Whittaker’s five kingdoms are monera, protista, plantae, fungi and animalia.
Three Domains of Life (Six Kingdom Classification) - 1990
- The three- domain system is a biological classification which was introduced by Carl Woese, a professor in the department of microbiology, university of Illinois, Urbana- Champaign in 1990 that divides cellular life forms into archaea, bacteria and eukarya domains.
- It emphasizes the separation of prokaryotes into two groups, originally called eubacteria (now bacteria) and archaebacteria (now archaea) because of their fundamental differences, Woese argued that each of the two arose separately from an ancestor with poorly developed genetic machinery, often called a progenote.
- In fact the three-domain system is loosely based on the traditional five- kingdom system but divides the monera into two ‘’domains’’, leaving the remaining eukaryotic kingdoms in the third domain.
It is actually a six kingdom classification.
(1) Archaea domain:
The demain contains prokaryotic organisms which have a monolayer core of lipids in the cell memebrane and distinct nucleotides in their 16S RNA. It contains a single kingdom.
Kingdom archaebacteria
The kingdom contain early prokaryotes which live in extreme environments,
For Example:
(a) Methanogens - metabolize hydrogen and carbon dioxide into methane.
(c) Thermoacidophiles – live in acid high temperatures (upto 110 degrees Celsius).
(2) Bacteria domain:
The domain contains prokaryotes which lack membrane covered cell organelles but do have a sort of micro chambers for separating various activities. There is a single kingdom.
The domain contains diverse type of bacteria having peptidoglycan cell wall, glycogen as food reserve,naked DNA coiled to form nucleoid, absence of sap vacuoles and presence of 70S ribosomes. Some common group are bacteria, my-coplasma, ctinomycetes, rickettsiae, spirochaetes, firmicutes, cyanobacteria.
(3) Eukarya domain. The domain contains eukaryotic organisms which originated by endosymbiotic association between some archaebacteria and eubacteria. It has four kingdoms- protista, fungi, plantae and animalia.
Viroids (L. Virus- Point, EIos – Diminutive)
- They are obligate parasites.
- The RNA is tightly folded to form circular or linear structure.
- Viroids are known to cuse diseases (some 20) in plants only, e,g,. potato spindle tuber, chrysanthemum stunt. Animal or human infection is not known.
- Viroud does not production is not very clear. Viroids particle can multiply by both RNA development and DNA dependent replication.
Prions (Prusiner,1983)
- They are highly resistant glycoprotein particles which function as infectious agents.
- They are formes due to mutation in gene PRNP.
- They can also act as catalyst converting normal protein into prion state.
- Prions are not affected by proteases, nucleases, temperature up to 800OC, UV radiations and formaldehyde.
- Prions accumulate in nervous tissue and bring its degeneration. Common diseases caused by them are scrapie of sheep, mad cow disease, cruetzfeldt-jakob disease (CJD) and kuru.
Comments
Post a Comment