CLASSIFICATION SYSTEM IN BIOLOGY.pdf
- 2. IMPORTANT TERMS RELATED TO CLASSIFICATION 1. Classification: it is the process of grouping animals and plants into convenient categories on the basis of certain traits. 2. Identification : it is determination of correct position of an organism in the classification. 3. Nomenclature : it is the process of giving scientific name to the organisms. 4. Systematic : this includes the classification, nomenclature and identification of organisms based on various parameter.
- 3. HISTORY OF CLASSIFICATION • Hippocrates : he classified animals into various groups like insects, fishes and birds , etc. • Aristotle : known as father of Zoology/biology. He had written Historia animalium. • Threophrastus : known as father of botany. • A Swedish naturalist named Carolus Linnaeus is considered the 'Father of Taxonomy' because, in the 1700s, he developed a way to name and organize species that we still use today. His two most important contributions to taxonomy were: 1) A hierarchical classification system 2) The system of binomial nomenclature
- 4. ROLE OF NOMENCLATURE • In binomial nomenclature each scientific name has 2 components : i) Generic name (Genus) ii) Specific name (Species) • The generic name begins with capital letter, whereas the specific name with small letter. • Both the generic and specific names are separately underlined (if handwritten), or given in italic (if printed) to indicate their Latin origin. • The first (generic) name is usually a noun, whereas the second (species) is an adjective.
- 5. HISTORY AND TYPES OF CLASSIFICATION 1. Artificial system of classification 2. Natural system classification 3. Numerical taxonomy/Quantitative taxonomy 4. Phylogenetic classification 5. Karyo-taxonomy 6. Experimental taxonomy 7. Chemo-taxonomy 8. Biochemical taxonomy 9. New systematics
- 6. Basic concept of taxonomic hierarchy • There are seven basic categories of hierarchy: 1. Kingdom 2. Phylum 3. Classes 4. Order 5. Families 6. Genus 7. Species
- 7. • Kingdoms - The most basic classification of living things is kingdoms. Currently there are five kingdoms (Monera Kingdom, Protista Kingdom, Fungi Kingdom, Plant Kingdom, and Animal Kingdom.). Living things are placed into certain kingdoms based on how they obtain their food, the types of cells that make up their body, and the number of cells they contain. • Phylum - The phylum is the next level following kingdom in the classification of living things. It is an attempt to find some kind of physical similarities among organisms within a kingdom. These physical similarities suggest that there is a common ancestry among those organisms in a particular phylum. • Classes - Classes are way to further divide organisms of a phylum. As you could probably guess, organisms of a class have even more in common than those in an entire phylum. Humans belong to the Mammal Class because we drink milk as a baby.
- 8. • Order - Organisms in each class are further broken down into orders. A taxonomy key is used to determine to which order an organism belongs. • Families - Orders are divided into families. Organisms within a family have more in common than with organisms in any classification level above it. Because they share so much in common, organisms of a family are said to be related to each other. Humans are in the Hominidae Family. • Genus is a way to describe the generic name for an organism. The genus classification is very specific so there are fewer organisms within each one. For this reason there are a lot of different genera among both animals and plants. When using taxonomy to name an organism, the genus is used to determine the first part of its two-part name. • Species are as specific as you can get. It is the lowest and most strict level of classification of living things. The main criterion for an organism to be placed in a particular species is the ability to breed with other organisms of that same species. The species of an organism determines the second part of its two-part name.
- 9. Example of taxonomy of humans • Common name : Human • Biological name : Homo sapiens • Domain :Eukarya • Kingdom : Animilia • Phylum : Chordate • Class : Mammalia • Order : Primates • Family : Hominidae • Genus : Homo • Species : sapien
- 10. Kingdom: Animalia Multicellular organisms; cells with a nucleus, with cell membranes but lacking cell walls Phylum: Chordata Animals with a spinal cord Class: Mammalia Warm-blooded chordates that bear live young; females have mammary glands that secrete milk to nourish young Order: Primates Mammals with collar bone; eyes face forward; grasping hands with fingers; two types of teeth (incisors and molars) Family: Hominidae Primates with upright posture, large brain, stereoscopic vision, flat face, different use of hands and feet Genus: Homo Hominids with S-curved spine, recognisable as human Species: Homo sapiens Humans with high forehead, well-developed chin, thin skull bones
- 11. BROAD CONCEPT CLASSIFICATION • There is a great diversity in structure, cellularity, habitat, mode of nutrition of different organisms in ecosystem. To understand these differences and similarities between different organisms, we can classify various animals and plants on the basis of the following parameters. 1. Cellularity 2. Ultra structure (Prokaryotes/Eukaryotes) 3. Energy and carbon utilization 4. Ammonia excretion 5. Habitat
- 12. 1) CELLULARITY • A cell is the structural and functional unit of life. The total number of cells present in an individual varies from one organism to the other. Based on the number of cells, organisms are classified into: 1. Unicellular Organisms 2. Multicellular Organisms
- 13. Unicellular Organisms • They are simple, minute, single-celled organisms, made up of a single cell which existed about 3.8 million years ago. • Bacteria , amoeba, Paramecium archaea, protozoa, unicellular algae, and unicellular fungi are the main groups of unicellular organisms. • These unicellular organisms are mostly invisible to the naked eye. Most of the unicellular organisms are prokaryotes. • Unicellular entities fulfil their nutritional requirements through a process known as phagocytosis. • They reproduce through asexual means through the process of replication. • Movement in unicellular entities is brought about through cilia, pseudopodia, flagella, etc • Examples : Amoeba, Paramecium , Plasmodium , Euglena etc.
- 15. Multicellular Organisms • Organisms which are composed of multiple cells are called multicellular organisms. These cells are attached to each other to form tissue and after that procedure a multicellular organism (Cells→ Tissues → Organs → Organ Systems) • Organisms including, animals, birds, plants, humans are the main groups of a multicellular organism. Most of the multicellular organisms are eukaryotes. • Most of these cells are visible to the naked eye. • Examples : Animal – Hydra , Plant – Spirogyra , Cyanobacteria such as Chara (Multicellular prokaryotic organisms) , Species of gymnosperms and angiosperm plants (Multicellular eukaryotic organisms)
- 17. 2)Ultra structure (Prokaryotes/Eukaryotes) • On the basis of internal structure of cell of an organisms, cells can be divided into : 1. Prokaryotic cell -A prokaryote is a single-celled organism that does not have a membrane-bound nucleus, mitochondria, or any other membrane-bound organelle. Example – bacteria
- 18. 2. Eukaryotic cell - Eukaryotic cells are cells that contain a true nucleus and membrane bound organelles, and are enclosed by a plasma membrane. Example – animal, plants, fungus etc.
- 20. 3) Energy and carbon utilization • On the basis of energy and carbon utilization, the organism are divided into 3 types.. 1. Autotrophs 2. Heterotrophs 3. Lithotrophs
- 21. Autotrophs • An autotroph is also derived from the Greek word, where auto means ‘self‘ and trophe means ‘nourishing‘. Hence these types are considered as primary producer, which are able to prepare their own food with the help of sunlight, water, and air. • The two major types of autotrophs are chemoautotrophs and photoautotrophs. • Photoautotroph mainly plants with green leaves like from the mosses to long trees, algae, phytoplankton and some bacteria uses a process called photosynthesis, where plants acquire energy from the sun and use them in converting carbon dioxide from the air and water from the soil into a nutrient called glucose.
- 22. • Chemoautotrophs derive energy for their life functions from inorganic chemicals. They feed on chemicals that are good electron donors, such as hydrogen sulfide, sulfur, or iron. • Like all autotrophs, chemoautotrophs are able to “fix” carbon. They take atoms of carbon from inorganic compounds, such as carbon dioxide, and using it to make organic compounds such as sugars, proteins, and lipids. • Chemoautotrophs are commonly found in environments where plants cannot survive, such as at the bottom of the ocean, or in acidic hot springs. • One type of chemoautotroph, Nitrosomonas, plays the crucially important role of fixing nitrogen in the soil of some ecosystems..
- 23. Heterotrophs • Heterotrophs is an organism that cannot manufacture its own food by carbon fixation and therefore derives its intake of nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are secondary and tertiary consumers. By consuming reduced carbon compounds, heterotrophs are able to use all the energy that they consume for growth, reproduction and other biological functions. • There are two forms of heterotroph. • Photo-heterotrophs use light for energy, although are unable to use carbon dioxide as their sole carbon source and, therefore, use organic compounds from their environment. Helio-bacteria and certain proteo--bacteria are photo- heterotrophs. • Chemo-heterotrophs obtain their energy from ingesting preformed organic energy sources such as lipids, carbohydrates and proteins which have been synthesized by other organisms. Example : human
- 24. Examples of Heterotroph • Herbivores: Heterotrophs that eat plants(producers) to obtain their nutrition are called herbivores, or primary consumers. • Carnivores : eat only other consumers. The energy carnivores can use as energy mainly comes from lipids (fats) that the herbivore has stored within its body. Small amounts of glycogen is stored within the liver and in the muscles and can be used for energy intake by carnivores, although the supply is not abundant. • Omnivores : eat both consumers and producers
- 25. • Lithotrophs are a diverse group of organisms using inorganic substrate (usually of mineral origin) to obtain reducing equivalents for use in biosynthesis (e.g., carbon dioxide fixation) or energy conservation (i.e., ATP production) via aerobic or anaerobic respiration. • An example of this is chemolithotrophic bacteria in giant tube worms or plastids, which are organelles within plant cells that may have evolved from photolithotrophic cyanobacteria-like organisms. • Lithotrophs belong to the domains Bacteria and Archaea. • The term "lithotroph" was created from the Greek terms 'lithos' (rock) and 'troph' (consumer), meaning "eaters of rock". • Many but not all lithoautotrophs are extremophiles.
- 27. 4) Ammonia excretion • Different animals expel different nitrogenous compounds. On the basis of the type of nitrogenous end product. There are 3 modes of excretion. They are: • (a) Ammonotelism • (b) Ureotelism • (c) Uricotelism
- 28. a) Ammonotelism : It is the type of excretion in which ammonia is the main nitrogenous waste material. Such animals are called ammonotelic. • It is found in aquatic animal groups like sponges, coelentrates, crustaceans, echinoderms, bony fish, tadpole larvae and salamander. b) Ureotelism : It is a type of excretion where urea is the main nitrogenous waste material. Animals showing ureotelism are called ureotelic animals. • Generally found in land animals which can afford to excrete sufficient volume of water or to concentrate urea in considerable quantity in the urine. It is commonly found in man, whales, seals, desert mammals like kangaroo rats, camels, toads, frogs, aquatic and semi aquatic reptiles like alligator, terrapins and turtles. c) Uricotelism : Elimination of uric acid as the main nitrogenous waste material is called uricotelism. Animals showing uricotelism are called uricotelic animals. • It is a common method seen in birds, land reptiles, insects, land snails and some land crustaceans.
- 29. Habitat • a habitat is the type of natural environment in which a particular species of organism lives. It is characterized by both physical and biological features. A species' habitat is those places where it can find food, shelter, protection and mates for reproduction. • Aquatic Habitats: The animals which live in water are called aquatic animals. According to the nature of the water aquatic animals may be marine or fresh-water. • Marine Animals: About three fourths of the earth’s surface is covered by the oceans. The salt water serves as the home for the marine animals who can survive neither in fresh water nor on land. • Fresh-Water Animals : :Fresh-water animals are found in ponds, pools, rivers, lakes and swamps. Some prefer to live in stagnant water but others choose the running stream.
- 30. • Terrestrial Habitats: Terrestrial animals are those who live on the land. They may be simple surface dwellers or they may burrow beneath the soil and thus become sub terrestrial. The surface communities may choose to live on rocks, or plains, or desert or damp forest. The aerial animals spend a part of their time in the air, but they depend on the surface for rest. A number of animals are arboreal, homing amongst the branches of the tree.
- 31. MOLECULAR BASIS OF CLASSIFICATION OF ORGANISMS
- 32. 3 Domains and 6 Kingdoms of Classification • Carl Woese et al. classified organisms into 3 domain classification based sequence of ribosomal RNA genes and formed the molecular basis of dividing all organisms into 6 kingdoms. 1. Domain Bacteria A. Kingdom Eubacteria : Unicellular and prokaryotic with peptidoglycan. 2. Domain Archaea A. Kingdom Archaea : Unicellular and prokaryotic without peptidoglycan.
- 33. 3. Domain Eukarya : C. Kingdom Protista : Unicellular/ Multi cellular and eukaryotic. D. Kingdom fungi : Unicellular/ multi cellular, eukaryotic and decomposers. E. Kingdom plantae : Multicellular, eukaryotic and autotrophic. F. Kingdom Animalia : Multi cellular, eukaryotic and heterotrophic.
- 34. Model organisms • A model organism is a species that has been widely studied , usually because it is easy to maintain and breed in a laboratory setting has particular experimental advantages. • These organisms have properties that made them excellent research subject.
- 35. The characteristics of model organisms 1. Relatively easy to grow and maintain in a restricted space. 2. Relatively short generation time. 3. Relatively well understood growth and development. 4. Relatively easy to provide necessary nutrients for growth 5. Closely resemble other organisms or system.
- 36. Different types of model organisms Genetic model organisms Experimental organisms Genomic model organisms Good candidates for genetic analysis. Good candidates for research in developmental biology. Good candidate for genome research. Breed in large numbers . Have short generation time, hence large scale crosses can be followed over generations. Produce robust embryos that can be easily manipulated and studied. Easy to manage genomes . genome is similar to human. Example : Drosophila Example : Frog Example : Rat
- 37. 3 types of model 1. Mammalian models : • Mouse (Mus musculus) 2. Non – mammalian models • Bacterium (Escherichia coli) • Baker’s yeast (Saccharomyces cerevisiae) • Nematode (Caenorhabditis elegans) • Fruit fly (Drosophila melanogaster) 3. Plant model • Arabidopsis thalania
- 38. E.coli • It is a natural mammalian gut bacteria used as model organism because.. 1. E.coli is a singled cell organism so its simple to study. 2. Its life cycle is short. 3. It easily grow on nutrient medium. 4. It can be easily genetically manipulated.
- 39. Mouse (Mus musculus) • It is a premier mammalian model organism because.. 1. It has close genetic and physiological similarities to human. 2. These are small, maintained easily and have a short life span. 3. All new drugs , treatments are tried on mice.
- 40. Fruit fly (Drosophila melanogaster) • It is a versatile model organism that has been used in biomedical research over a century because.. 1. Relationship between human genes and fruit fly genes is close. 2. 75% of genes that cause human diseases are found in fruit fly. 3. They have a short life span 4. These are inexpensive to maintain 5. It is easy to manipulate genes in fruit fly.
- 41. Yeast (saccharomyces cerevisiae) • Yeast is one of the simplest eukaryotic organisms but many essential cellular processes are the same in yeast and human. • Baker’s or budding yeast model has long popular model organisms for basic biological research because… 1. It is easy to manipulate in lab 2. Yeast shows cell division in a similar way to our cells. In 1996, it was the first eukaryotic organisms to have its genome sequence. 3. 20% of genes causing diseases are found in yeast. 4. Many drugs are tested on yeast which have functional equivalent of mutated human genes to reverse the disease.
- 42. Nematode (caenorhabditis elegans) • At approximately 1mm in length and transparent. It is used as model organisms because… 1. It can easily grow in labs on nutrient medium 2. It produces over thousands egg each day 3. Worm is transparent so its cells can be easily studied. 4. Its genes can be easily mutated.
- 43. A. thalania • It is a small flowering plant, used as model organisms in plant biology. • Arabidopsis is a member of the mustard family, it is used as a model organism because.. 1. It has a short life span 2. It can be easily cultivated 3. Mutations can be easily produced in this plants.