Biological Classification PDF

Biological Classification Introduction Demerits of the Classification Classification is the arrangement of His classification could not be accepted organisms into groups (taxa) based as- upon their distinctive charact...

Biological Classification Introduction Demerits of the Classification Classification is the arrangement of His classification could not be accepted organisms into groups (taxa) based as- upon their distinctive characteristics y It was an artificial system of reflecting their similarities and classification. dissimilarities. Classification of living y Certain animals lived in two different organisms is essential because: habitats like amphibians and thus their y It makes the study of all living organisms placement was confusing. easy and convenient. The study of one or two organisms can help us to Theophrastus is known as the “Father understand distinctive features of entire of Botany”. He classified plants. Based group. upon habitat, form and texture, he y It makes the study systematic. grouped plants into herbs, shrubs, y It helps in understanding relationships undershrubs and trees. between different groups of organisms. ⚪ He talked about 480 plants in his y It helps in studying the evolutionary book “Historia Plantarum.” relationships between organisms. ⚪ This book “De Historia plantarum” (enquiry into plants) is in ten volumes, HISTORY OF CLASSIFICATION where in Theophrastus described First attempt at classification was made plants, by their uses and attempted by a Greek philosopher, Aristotle, also biological classification of plants known as the “Father of Zoology”. He based on how plants reproduce. This classified animals- attempt was the first of its kind in y In two main groups- Anaima the history of Botany. (Invertebrates) and Enaima (vertebrates), ⚪ In volume nine of Historia Plantarum, lacking red blood cells and having red medicinal uses of plants is described. blood cells respectively. ⚪ This book is one of the first books to y Classified organisms on the basis of contain a description of plant juices, their habitat into aquatic, aerial and gums and resins/their extractions. terrestrial. y Classified plants on the basis of stem Candolle or Augustin Pyramus de and life duration into herbs, shrubs and Candolle or Pyrame de Candolle trees. (Swiss Botanists) introduced the term ‘TAXONOMY’ in his book Théorie Definition Élémentaire de La botanique (Elementary Biological Classification Theory of Botany), in the year 1813. Classification: Systematic arrangement of organisms into categories according John Ray, a naturalist, was the first to their similarities and differences. to apply the concept of “species” to classification. He introduced and defined the term species. His book 1. Chapter “Historia Generalis Plantarum” contains of the sex organs. Linnaeus also put description of more than 18,000 plants forward an artificial system of plant and animals. He divided plants into two classification on the basis of numerical divisions –Imperfect and Perfect. He strength of sex organs into 24 classes further divided Plantae perfecta into like monandria, diandria, polyandria, different life forms like trees, shrubs, didynamia, monoecia, cryptogamia, etc. sub-shrubs and herbaceous plants. Carolus Linnaeus a Swedish naturalist, known as the “Father of Taxonomy”. He gave the sexual system of classification in 1758. ⚪ He listed all animals known to him in his book “Systema Naturae.” He characterized and named over 4400 species of animals. ⚪ Similarly, he named over 8,000 species of plants in his book “Species Plantarum.” ⚪ He also gave taxonomical hierarchy. Carolus Linnaeus George Bentham and Joseph Dalton Hooker (1862- 1883) gave the Natural Demerits of Artificial System of system of classification of seeded Classification plants. Their book “Genera Plantarum” It could not be accepted as- have a description of 202 families of y It was based on superficial Angiosperms. characteristics. Adolf Engler and Karl Prantl gave y It did not take into account the phylogenetic system of classification relationship between the different of plants in their book ‘Die Naturlichen organisms. Pflanzenfamilien’. y Organisms belonging to different groups were placed together e.g., birds and SYSTEMS OF CLASSIFICATION bats were placed in the same group due Types of Classification to their ability to flight. 1 Artificial System of Classification y Separated the closely related species. 2. Natural System of Classification 2. Natural System of Classification Biological Classification 3. Phylogenetic System of Classification It was based on natural affinities 1. Artificial System of Classification among the organisms. It was based This type of classification is based on considering the morphology, on habitat, external features, i.e., ultrastructure, anatomy, embryology morphology or on the numeric number and physiochemistry. 2.  Chapter Merits of Natural System of represented in form of a family tree, Classification called a cladogram. It is better than the artificial system of Information from Numerical Taxonomy, classification as - Cytotaxonomy, Chemotaxonomy helps y It does not consider habit and habitat in resolving difficulties in classification. as characteristics for classifying y Cytotaxonomy- It is based on the study organisms. of Chromosome number, structure, y It considered characteristics of each behaviour during cell division and the and every organism. banding pattern of chromosomes. It y It helped the related organisms to be helps in finding the lineage and similarity placed in one group only. among the organisms. y The system prevents placing together y Chemotaxonomy- It is based on the the non-related organisms. different chemical constituents of the y The system indicates phylogenetic organisms like amino acids, alkaloids, relationships and the origin of different proteins, etc. The chemical constituents taxa. of the plants are specific and stable, thus help in classification. Gray Matter Alert!!! y Numerical Taxonomy- Number and codes are assigned to all the characters and the data is then processed. Each Molecular homology: It is the study of character under consideration is given similarities and differences between a certain number and codes. Then DNA, RNA and proteins of different these characters are used to establish organisms. a numerical degree of relationship between the organisms. Computers make numerical taxonomic studies Demerit of Natural System of easier. Classification y It does not consider habit and habitat as characteristics for classification. Gray Matter Alert!!! 3. Phylogenetic System of Alpha Taxonomy: Based on Classification morphological features. It is based on evolutionary relationship Beta Taxonomy: Based on between different organisms. This morphological, anatomical, Biological Classification classification assumes that the cytological, embryological features organisms belonging to the same and biochemistry. taxa may have a common ancestor. In Gamma Taxonomy: Based on such a system, organisms belonging experimental, genetic and evolutionary to the same group are believed to evidences. have a common ancestry and maybe 3. Chapter Two Kingdom Classification System Demerits of Two Kingdom Classification y It was given by Linnaeus in 1758. System y Based upon y First formed organisms as reported, ⚪ Mode of nutrition were neither plants nor animals. ⚪ Presence or absence of cell wall y It did not distinguish between ⚪ Locomotion prokaryotes and eukaryotes and placed ⚪ Response to stimuli bacteria along with eukaryotic groups in ⚪ Divided all living organisms into two the plants. kingdoms: Plantae and Animalia. y Fungi were placed in kingdom Plantae, y Kingdom Plantae was characterized. whereas structurally, physiologically ⚪ By the presence of cell wall and and reproductively, they differed from central vacuole plants. ⚪ Autotrophic nutrition y Lower organisms like Euglena, ⚪ absence of nervous system, sense Chlamydomonas, Slime mould have organs and locomotion been considered by both zoologists ⚪ Starch as reserve food material and botanists. Their placement in this ⚪ Well defined growing points with system was ambiguous. unlimited growth. In order to address these discrepancies, y He placed bacteria, fungi, algae, two kingdom classification system was bryophyte, pteridophyte, gymnosperms modified to three kingdom classification and angiosperms in plant kingdom. system. y Kingdom Animalia on the other hand: ⚪ Showed absence of cell wall and Three Kingdom Classification System central vacuole. y Ernst Haeckel added a new kingdom ⚪ Demonstrates heterotrophic Protista and gave us three kingdom nutrition, presence of nervous system. system, sense organs and y This system classified all the living locomotion. organisms into three kingdoms- ⚪ Glycogen as reserve food material ⚪ Protista and absence of well-defined growing ⚪ Plantae points and limited growth. ⚪ Animalia y Protists comprised of bacteria, blue Merits of Two Kingdom Classification green algae, mycoplasma, unicellular System Protozoa, some simple unicellular green y The advantage of two kingdom algae, whole group of Charophyceae and Biological Classification classification was that it initiated the Bacillariophyceae algae, fungi and slime first systematic way of classifying moulds. All these organisms lacked the organisms. capability of tissue differentiation. y This system was adopted by the biologists all over the world for a long time but it showed many inconsistencies. 4.  Chapter y Based upon the simple cell structure -Without true nucleus and membrane bound organelles. y Mycoplasma and prokaryotic forms of primitive organisms were placed in this group. y Kingdom Monera consisted of all the Prokaryotic forms. Kingdom Monera was initially called Mycota. Thus, four kingdoms comprised of Kingdom Monera, Protista, Metaphyta and Metazoa. Ernst Haeckel Merit of Four Kingdom Classification System It created the kingdom Monera. Merit of Three Kingdom Classification System Demerits of Four Kingdom Classification y The advantage of three-kingdom System classification was placing the unicellular y Prokaryotes and Eukaryotes were organisms in a different group called placed together. Protista. y Both unicellular and multicellular organisms are placed under Protista. Demerits of Three Kingdom y Heterotrophic bacteria and fungi cannot Classification System prepare their own food but still were The drawbacks of this classification placed along with autotrophic algae. was- y All Prokaryotic and Eukaryotic unicellular Five Kingdom Classification System organisms were placed in one group. y In 1969 Robert Harding Whittaker Fungi were not classified properly. proposed this system of classification y No mention of the Virus and added kingdom Fungi. He argued Both unicellular and multicellular that fungi, which had been previously organisms were placed under Protista placed along with plants, had a unique Heterotrophic bacteria and fungi that method of obtaining food. So, he cannot prepare their own food but still proposed Kingdom Fungi and separated Biological Classification were placed along with autotrophic it from plants. algae. y Living organisms are divided into five kingdoms; Monera, Protista, Fungi, Four Kingdom Classification System Plantae and Animalia. y In 1956, Lynn Margulis and Copeland added a new kingdom Monera. 5. Chapter Demerit of Five Kingdom Classification System y Though it led to a better arrangement of taxa, still it lacked the systematic position of viruses and lichens. Three Domains of Life or Six Kingdom Classification System y It was introduced by Carl Woese that divides different life forms into three domains- ⚪ Archaea ⚪ Bacteria ⚪ Eukarya Robert Whittaker y He proposed that on the basis of differences in 16S rRNA genes, each Criteria used by Whittaker for his domain arose separately from an classification scheme was: ancestor called as progenote. y Cell structure y Domain Archaea contains the kingdom y Body organization Archaebacteria. y Mode of nutrition y Domain Bacteria contains the kingdom y Reproduction Eubacteria y Phylogenetic relationships y Domain Eukarya consists of Protista, Fungi, Plantae and Animalia. This classification system placed all prokaryotes in the Kingdom Monera and unicellular eukaryotes were placed in the kingdom Protista. Fungi were elevated to the level of kingdom. Merits of Five Kingdom Classification System y It removed most of the confusions of the kingdom system. y It gave just treatment to all groups of Biological Classification organisms. It reflected phylogenetic relationships amongst groups. Carl Woese 6.  Chapter Merits of Six Kingdom Classification Archaebacteria (Archaea – ancient: System bact – rod) y Prokaryotes are separated into two y These are most simple and ancient groups on the basis of basic differences bacteria which were probably the first and this helps in determining the genetic to evolve. similarities between organisms. y Archaebacteria are popularly known as They are grouped in such a way that the “Oldest of living fossils”. their features can indicate a common y It is a most unusual group of bacteria ancestor which are capable of growing under extreme conditions. Demerits of Six Kingdom Classification y Structurally, they resemble prokaryotes System (except for cell wall which is not made y It is time consuming and the scientists of peptidoglycan) but metabolically have to study minute details in order to they differ from them. The cell wall place the animals in different domains is composed of non–cellulosic specially the Domain Archaebacteria polysaccharide and proteins. This and Domain Bacteria. cell wall gives them ability to survive y Viruses and lichens do not have any under conditions of extremely high pH, position in this classification also. temperature and salinity. y Most of them are chemoautotrophs. KINGDOM MONERA y Types of archaebacteria: It comprises of most primitive and (i) Methanogens simplest organisms. All prokaryotes (ii) Halophiles such as bacteria, Mycoplasma and blue (iii) Thermoacidophiles green algae are placed in this group. Methanogens Characteristics y These are strictly anaerobes. y Unicellular, organisms having prokaryotic y Generally present in marshy areas or gut cell structure. of several ruminants like goat, cows and y Cell wall is made of peptidoglycan. buffaloes. They ferment the cellulose, Cellulose is absent. which forms the main food of these y Naked DNA lies in the cytoplasm in a ruminants. coiled form. It is called a nucleoid. y They are responsible for the production y Nutrition is autotrophic, saprophytic, of about 65% of atmospheric methane. parasitic and symbiotic. This property of Methanogens is used in Biological Classification y Asexual mode of reproduction. Gametes biogas plants. are absent. Example: Methanobacterium, y Kingdom Monera includes Methanococcus, Methanogenium, Archaebacteria, Eubacteria, Methanospirillum Cyanobacteria and Mycoplasma 7. Chapter Halophiles organisms and in all environments y Mostly anaerobes, they are found in where life can exist. extremely salty environments like Bacteria are classified into different marshes, salt lakes etc. types using different criteria:- y No photosynthetic activity has been found. They can convert light energy to Gray Matter Alert!!! ATP. y Halophiles contain ‘Halorhodospin’. This Largest Bacterium: Thiomargarita chemical pumps in chloride into the cell namibiensis – Ocean shelf of Namibia. and prevents cellular dehydration. Example: Halobacterium, Halococcus, Haloferax Based upon the shape, they are of four types: Thermoacidophiles y Coccus: These are spherical shaped y These are temperature and acid loving bacteria that lack flagella. Spheres bacteria. They occur in hot Sulphur can occur singly (Monococcus), springs They can live in extreme in pair (Diplococcus), in clusters temperature and acidic pH. (Staphylococcus) or change chains y Thermoacidophiles survive in extreme (Streptococcus). temperature and acidic pH due to: y Bacillus: These are rod shaped bacteria. ⚪ Presence of special branched chain They may occur singly (Monobacillus), lipids in their cell membrane which in pair (Diplobacillus), in clusters reduces cell fluidity. (Staphylobacillus) or in chains ⚪ Ability of enzymes to work at low (Streptobacillus). pH. y Spirillum: These are bacteria that are ⚪ Resistance of enzymes to high screw shaped or are twisted. They occur temperature. as single cells. y Vibrio: These are comma shaped Under anaerobic conditions they oxidise bacteria. They occur as single cells. sulphur to sulphuric acid. 2S + 2H2O + 3O2 → 2H2SO4 + Energy Based upon Gram staining, they are of Example: Sulpholobus, Desulphurolobus two types: y Gram positive Example: Bacillus, Eubacteria (True bacteria) Clostridium Antonie van Leeuwenhoek (1683) Gram negative Example: Pseudomonas, Biological Classification observed small animalcules in decaying Salmonella tooth scum, under his self made microscope. Ehrenberg (1829) gave the Technique of Gram Staining term “Bacteria.” The differential staining technique was Bacteria are omnipresent and can be introduced by Hans Christian Gram found in water, air, soil, in and on other (1884), hence it is called Gram stain. The 8. 9. Biological Classification Chapter Chapter main stain used is 1% solution of crystal y Then it is washed with alcohol. If the violet or gentian violet. cells retain the colour, they are gram y Heat treated bacteria is stained with an positive and if the cells do not retain aqueous solution of crystal violet for 1-2 the colour, they are gram negative. minutes. Then it is transferred to iodine y Gram negative bacteria are then solution (iodine dissolved in potassium stained with a counterstain like eosin iodide solution). Iodine solution acts as or safranin to make them visible under mordant and makes the cell wall accept microscope. the Gram stain easily. The difference in the ability to retain colour is because of different structures of the bacterial cell wall. Gram Positive Gram Negative Biological Classification Fig: Cell Wall of Gram Positive and Gram Negative Bacteria 10.  Chapter Difference between Gram positive and Gram negative Bacteria. CHARACTER GRAM POSITIVE GRAM NEGATIVE Number of layers One Two Thickness Thick (20-80 nm) Thin (8-10 nm) Lipopolysaccharide, Chemical Peptidoglycan, Teichoic Lipoproteins and composition acid and lipoteichoic acid peptidoglycan Lipid Less More Peptidoglycan More Less Based Upon Flagellation, they are of General Structure Of Bacterial Cell two types: Cell Structure: Bacteria have typical y Atrichous: These are bacteria without prokaryotic cell structure. Cell is flagella. All coccus forms are atrichous. surrounded by a rigid cell wall which y Trichous: These are the bacteria that do is made of peptidoglycan. Cell wall is have flagella. Depending upon number further surrounded by mucilaginous of flagella, they may be- sheath. Inside cell wall, cell membrane ⚪ Monotrichous: Bacteria having a is present. Membrane bound organelles single flagellum attached at one and a well-defined nucleus is absent. end. Example: Vibrio cholerae. Genetic material consists of single ⚪ Lophotrichous: Bacterial cell having circular naked segment of DNA which tuft of flagella attached at one end. is known as nucleoid or genophore or Example: Spirillum volutans. incipient nucleus. It is rich in Guanine ⚪ Amphitrichous: Bacteria having one and Cytosine. Extra chromosomal Biological Classification or more flagella attached at both material Plasmid is present in the cell ends. Example: Nitrosomonas. which provide antibiotic resistance to ⚪ Peritrichous: Bacteria having flagella the bacteria. evenly distributed throughout the surface of bacterial cells. Example Cell Membrane: It is a living, elastic, E. Coli. semi-permeable membrane which 11. Chapter regulates the flow of material in and Respiration in Bacteria out of the cell. It shows invaginations to Respiration: Based upon the mode of form mesosomes. respiration, bacteria are of two types:- Cytoplasm: It is a colorless, colloidal, y Aerobes and Anaerobes. homogenous material which lacks any y Each group is further subdivided into membrane bound cell organelle. It does facultative and obligate types. not show streaming movement and appears granular due to the presence of 70S ribosomes. These ribosomes Definition generally lie scattered in cytoplasm. Sometimes, they may form a small Facultative Aerobes: Organisms that chain of 4 – 6 ribosomes attached are chiefly anaerobic but can respire to mRNA. This structure is called in the presence of oxygen also. polyribosome. Some bacteria living in aquatic conditions may show sap or gas vacuoles, otherwise these vacuoles are Obligate aerobes: These are the bacteria Biological Classification absent. that respire only in the presence of oxygen. Example: Bacillus subtilis Rack your Brain Facultative aerobes: These are the bacteria that normally respire in Which is the most essential unit for a absence of oxygen but can respire in it’s living cell to sustain limited life span? presence also. Example: Chlorobium. 12.  Chapter Photosynthetic bacteria, Green Sulphur Definition bacteria or Purple Sulphur bacteria are obligate anaerobes. Thus, their Facultative Anaerobes: Organisms photosynthesis is anoxygenic. They use that are chiefly aerobic but can H2S as hydrogen donor instead of H2O. respire in the absence of oxygen. Most of the pathogenic forms are anaerobes. Facultative anaerobes: These are Nutrition in Bacteria the bacteria that normally respire in Nutrition: Bacteria show both the the presence of oxygen. However, if modes of nutrition: sufficient oxygen is not available, they y Autotrophic can switch over to anaerobic respiration y Heterotrophic to get energy. Example: Pseudomonas. Autotrophic Nutrition Obligate anaerobes: These are the y It is shown by less than 1% of bacteria that respire only in the absence bacteria. Bacteria showing this Biological Classification of oxygen. Since the amount of energy mode maybe photoautotrophic or liberated during anaerobic respiration chemoheterotrophic. is less, the rate of growth of these anaerobic bacteria is slow. Example: Photoautotrophic bacteria Clostridium botulinum. y These bacteria have a photosynthetic pigments like bacteriochlorophyll 13. Chapter (found in purple bacteria), bacteriopheophytin, chlorophyll (found Definition in green sulphur bacteria). y By using these pigments, they trap the Chemoautotrophs: Organisms that solar energy and synthesize food for are able to manufacture their own themselves. These pigments occur in organic food from inorganic raw membranes of thylakoids. materials. y The photosynthesis shown by these bacteria is anoxygenic. No oxygen is Nitrifying bacteria – Nitrosomonas evolved during this photosynthesis and Nitrosococcus oxidize ammonia to as they do not use water as a reducing nitrite and release energy. agent. Therefore, these monerans are 2NH4+ + 3O2 → 2NO2– + 2H2O + 4H+ + Energy commonly found near the bottom Nitrobacter oxidizes nitrites into of pond or lake. At the bottom of nitrates. these water bodies, reduced sulphur and 2NO2– + O2 → 2NO3– + Energy other compounds are easily available. y Hydrogen is obtained either directly Sulfur oxidizing bacteria- A colourless or from various inorganic or organic sulfur bacteria oxidizes hydrogen compounds like H2S (Green bacteria). sulphide into Sulphur to obtain energy y Bacteriochlorophyll, bacteriopurpurin 2H2S + O2 → 2S + 2H2O + Energy and Bacterioviridin are pigments Iron bacteria- The bacteria Ferrobacillus that are found in different bacteria. ferrooxidans obtain energy by the These pigments are present in the oxidation of oxidized ferrous ions into chromatophores. ferric form. 4FeCO3 + 6H2O + 3O2 → Chemoautotrophic bacteria 4Fe (OH)3 + 4CO2 + Energy y These bacteria are able to manufacture their own organic food from inorganic Heterotrophic bacteria raw materials. The energy needed is These obtain energy from the external obtained from the oxidation of inorganic source as they cannot manufacture materials. their own food. y The energy used is ATP. Different types They are: of chemoautotrophic bacteria are- Saprophytic y Nitrifying bacteria Symbiotic y Sulfur oxidizing bacteria Parasitic Biological Classification y Iron bacteria Saprophytic bacteria y These are the free-living bacteria which obtain their energy from the dead and decayed organic matter like fallen leaves, vegetable and fruit leaves, 14.  Chapter animal excreta and corpses of animals. y One of the most important examples Breakdown of organic compounds is the association of Rhizobium in the aerobically is known as decay. root nodules of leguminous plants. y They break the complex organic matter Rhizobium fixes atmospheric nitrogen in into soluble form. the form of nitrates in the soil. In return y Anaerobic breakdown of carbohydrates the bacteria get shelter and food from is known as fermentation. the plants. y While the anaerobic breakdown of y Escherichia coli lives in human intestine, proteins is known as putrefaction. where it produces vitamin B and K y The bacteria play an important role in and prevents the growth of putrefying the environment by decomposing the bacteria. dead organic matter. They can be called as nature’s scavengers or cleaners of Parasitic bacteria the environment. y They live in contact with other living organisms. Symbiotic bacteria y They cause diseases due to the y They live in an association with other breakdown of the host cells or due to living organisms where both are the secretion of toxic substances. benefitted. NAME OF DISEASE (IN ANIMALS) CAUSATIVE BACTERIA Pneumonia Diplococcus pneumoniae Typhoid Salmonella typhii Cholera Vibrio cholerae Plague Pasteurella pestis Biological Classification Gonorrhea Neisseria gonorrhoeae Gastroenteritis E. coli 15. Chapter NAME OF DISEASE (IN PLANTS) CAUSATIVE BACTERIA Soft rot of potato Pseudomonas solanacearum Citrus canker Xanthomonas citri Bacterial blight of paddy Xanthomonas oryzae Tundu disease in wheat Corynebacterium tritici Potato wilt Pseudomonas solanacearum Fire blight of apple and peach Erwinia amylovora Crown gall of sugar beet Agrobacterium tumefaciens Reproduction in Bacteria Mesosomes leading to the formation Reproduction: These reproduce of two daughter cells, thus pushing asexually by binary fission and tide the DNA towards the two poles. The over unfavorable conditions through cytoplasm divides finally and forms two endospore and perinate. Sexual daughter cells. reproduction is absent, but the exchange of genetic material takes place. Endospore Endospores are thick-walled resting Binary Fission: Mature bacterium spores that are formed in adverse divides into two equal daughters. environmental conditions. Dehydration Similar to amitosis, it does not involve and drying separate a part of the the formation of a spindle. The DNA protoplasm with the nuclear material Biological Classification uncoils and replicates attached to known as the endospore primordium. the Mesosome. A new Mesosome is Walls get deposited over this primordium formed which gets attached to the and form the endospore. The parent newly replicated DNA. Formation of a cell undergoes lysis and the liberated membrane takes place between the two endospore germinates under favorable conditions to form one bacterium. 16.  Chapter There is no multiplication taking place, but the survival of the individual takes place. Hence cannot be considered as a method of reproduction. It is formed in Bacillus and Clostridium. Fig: Endospore of Bacteria Advantages of endospore formation exchanged by- 1. Resistant to high temperature y Sterile Male Method: The (1000C). bacteria having a plasmid with a 2. Tolerate toxic substances. fertility factor will replicate and 3. Produce anticoagulant chemical – get transferred to the recipient Dipicolinic acid. cell. The recipient becomes a donor. Genetic Recombination y Fertile Male Method: The fertility It is of the following types- factor gets integrated with the y Conjugation genome of the male and F+ male y Transformation becomes Hfr male that is high y Transduction fertility male or super male. When (a) Conjugation- Lederberg and the F factor is detached from Tatum, first observed Conjugation Hfr, it converts back to F+ male. in Escherichia coli. Bacteria are The Hfr and F- female connects dimorphic i.e., have male or donor with the sex pilus. The integrated (F+) and female or recipient (F-). DNA with the Hfr breaks and Male/Donor have sex pili on their replicates. This replicated DNA surface and fertility factor in their moves to the female cell.The plasmid. Fertility factor is responsible segment replaces a homologous for producing the sex pili and for segment in the F- cell. Thus a the other factors needed for gene new recombinant is formed. Biological Classification transfer. Both sex pili and fertility (b) Transformation-Griffith in the year factors are absent in the female. 1928, conducted an experiment on Sex pili form a protoplasmic bridge Diplococcus pneumoniae. It has two or conjugation tube with the female strains- recipient. Genetic material can be y R type i.e a non-virulent strain, cannot cause disease. 17. Chapter Transformation has also been reported in Bacillus, Haemophilus and Neisseria (c) Transduction-Discovered first time in Salmonella typhimurium by Zinder and Lederberg. A process of genetic recombination in bacteria in which genes from a bacterium are incorporated into the genome of a bacteriophage and then carried to another host cell, when the bacteriophage initiates another cycle of Fig: Conjugation in Bacteria infection. It is of three types: y S type i.e virulent type, can y Generalized transduction cause a disease as it has a y Restricted/Specialized polysaccharide coat. transduction y He took both the different types y Abortive transduction of strains and injected them into Generalized transduction –It is the mice and saw the results. transfer of any gene of the donor y R type injected into the mice → bacterium e.g., T4 - bacteriophage. Mice lived. Restricted/Specialized transduction y S type injected into the mice –It can carry only a specific region of →The mice died. the bacterial DNA to a recipient e.g., y S type strain was heat killed and Bacteriophage. inserted into the mice → The Abortive transduction –In this, the donor mice lived. bacterium gene is not integrated into y R strain and heat killed S strain the genome of the recipient bacterium injected into the mice → The and is lost after a few generations. mice died. Economic Importance of Eubacteria Through this Griffith arrived at a Useful effects conclusion with a transformation (a) In Agriculture: principle that transforms the non- y In soil fertility: Bacteria convert virulent strain into the virulent one. Later atmospheric free nitrogen into Biological Classification Avery, MacLeod and McCarty separated nitrogenous compounds. the carbohydrates, DNA and proteins Example: Azotobacter and from the dead mice and through the Clostridium, Nitrosomonas, addition of proteases, DNAase and Nitrosococcus. RNAase respectively, showed that DNA y Decay and decomposition of dead is the transforming principle. plants and animals and converts 18.  Chapter their complex compounds into simpler substances. (b) In dairy: y Lactobacillus converts milk into curd. It converts lactose sugar found in milk to form lactic acid. y Formation of cheese. Rack your Brain Which bacteria help to maintain the purity of the Ganges? (c) In industry: y Alcoholic Beverages are prepared from different raw materials using the bacteria. y Vinegar is produced by Acetobacter aceti. y Linum usitatissimum, Cannabis sativa and Corchorus capsularis (Jute) are retted by the bacteria. y Micrococcus candidans is used for curing the tea leaves which helps in developing the taste in the leaves. y Leather is tanned by bacteria. (d) In medicines: y Manufacture of antibiotics. Antibiotics are chemical substances produced by living microorganisms and are capable of inhibiting or destroying other Biological Classification microbes. Harmful effects (a) Food poisoning (Botulism): It is caused by Clostridium botulinum. Fig: Transduction in Bacteria The main symptoms are vomiting, 19. Chapter followed by paralysis and even death in some cases. (b) Biological warfare: Bacteria that cause diseases like anthrax, blackleg are used for biological warfare. (c) Putrefaction: It is the spoilage of protein, anaerobically by the putrefying bacteria e.g., Proteus, Mycoides. Cyanobacteria (Blue green algae) y These are gram positive, photosynthetic prokaryotes. y They are found in fresh water, sea water, moist rocks, moist soil, hot springs and frozen waters. They live under many different types of environments and thus are considered the colonizers of the barren land. y They are unicellular, colonial or filamentous. Each filament consists of mucilage sheath. The cells have nucleoid Fig: A Filament of Anabaena bearing and lack membrane bound organelles. Heterocyst and Akinete y The photosynthetic pigments present are chlorophyll a, beta carotene, C– break into a number of pieces by the phycocyanin and C–phycoerythrin. decay of the vegetative cell which forms C–phycocyanin gives blue and C– a separation disc and thus separating the phycoerythrin gives red colour. pieces. Each separated piece is known y They have special structures known as a hormogonium which develops into as heterocyst which are present in a new Cyanobacteria. the intercalary or lateral position. Heterocyst has an enzyme nitrogenase, Resting spore or Akinetes- An akinete which helps in fixing the atmospheric is an enveloped, thick-walled, non- nitrogen in the form of nitrates in the motile, dormant cell that is formed soil. by filamentous, heterocyst-forming Biological Classification y Cyanobacteria reproduce asexually cyanobacteria. They can tide over by fragmentation, binary fission, unfavorable conditions and once endospores and hormogonia. favorable conditions return, on absorbing moisture germinates into a Hormogonia- Hormogonia are formed by new filament. some Cyanobacteria, the filament may 20.  Chapter Economic Importance of Cyanobacteria Useful activities y Production of oxygen through photosynthesis. y Used as biofertilizers. Nostoc is important for their nitrogen-fixing ability. It is used in paddy fields. y Anabaena and Aulosira prevent mosquitoes from breeding. y Nostoc commune, Cylindrospermum Fig: Mycoplasma muscicola are used in the reclamation of ‘usar’ land that is sterile alkaline soil. are parasitic. They cause diseases in plants and animals. They cause Harmful activities pleuropneumonia in domestic animals, y They cause algal bloom, causing the little leaf disease of Brinjal, Witches’ deterioration of the water bodies. broom, Papaya bunchy top, Potato Produce an odour in the water and purple top in plants. block the water supply system. y They produce toxic chemicals which is harmful to humans and animals. Rack your Brain Mycoplasma (P.P.L.O. - PleuroPneumonia DNA of which organism possesses a Like Organisms) replicating disc? y These are the simplest of all the living forms. They were discovered by Nocard and Roux in 1898, in cattle suffering Actinomycetes from pleuropneumonia. y These are generally gram positive and y They do not have a regular shape and anaerobic. They are found in soil and hence are known as the ‘Joker of the decaying organic matter and also in microbial world’. The plasma membrane humans and animals. is present while cell wall is absent. y Streptomycin, Actinomycin are y Membrane bound organelles are absent. antibiotics isolated from Actinomycetes They are resistant to Penicillin but not bacteria. against Tetracyclines. y It has a double helix DNA. It has RNA Spirochaetes Biological Classification and ribosomes that help in protein y Coiled aflagellate bacteria. They cause synthesis. diseases like Syphilis in human. y It multiplies by budding off minute elementary bodies. Rickettsia y Mycoplasma are heterotrophic. They y First discovered by Ricketts in 1909 and are saprophytic and most of them described by Rocha Lima in 1916. 21. Chapter y Rod or circular obligate parasites. Photosynthetic Protists or Protistan y They have a mucopeptide cell wall and Algae DNA as their genetic material. They are photosynthetic and are divided y Asexual reproduction occurs by into three groups- Dinoflagellates, fragmentation, conidia and oidia Chrysophytes and Euglenoids formation. y The endospores are not formed. Dinoflagellates y They are sensitive to antibiotics like Characteristics: Chloramphenicol, Tetracycline. They y Most of these are marine and are cause Q fever, rock mountain spotted photosynthetic. Unicellular, motile with fever, rickettsial pox in humans. two flagella. One flagellum projecting from one end and the other lies in KINGDOM PROTISTA the transverse groove between the Characteristics wall plates. They appear green, yellow, y These are unicellular, eukaryotes that blue or red depending on the pigments can be solitary and colonial. present in high concentration in their y They are surrounded by a cell membrane cells. which may be covered by the pellicle, shell or cellulosic wall. They have membrane bound organelles. y Locomotion is brought about by the pseudopodia, flagella and cilia. y Nutrition may be photosynthetic, holozoic, parasitic and mixotrophic. Mixotrophic nutrition is a mixed nutrition where the organism can perform two different modes of nutrition depending Fig: Dinoflagellates on the environmental conditions. Example: Euglena is both photosynthetic y They are surrounded by a cell wall made and parasitic. up of cellulose, which is composed up of y Reproduction by asexual and sexual two plates interlocking each other. This methods. gives them an appearance of armoured y The kingdom Protista is broadly divided dinoflagellates. into three groups namely- Reproduces asexually. Sexual y Photosynthetic Protists or Protistan reproduction is absent in them except Biological Classification Algae Ceratium. y Consumer – Decomposer Protists-Slime y Gymnodinium and Gonyaulax grow in Moulds large numbers in the sea, giving it a red y Protozoan Protists colour and thus causes the red tide. 22.  Chapter Gonyaulax catenella when present in y Cell is called frustules. The cell wall large numbers produces a toxin saxitoxin is made up of two halves fitting each which is poisonous to the fishes and other like a soap box and hence known marine animals. as diatom. The cell wall is made up of y Examples: Ceratium, Noctiluca, silica. Peridinium y Diatoms are the main producers in the oceans. The cell wall of the desmids does not decay easily, they accumulate Gray Matter Alert!!! at the bottom of the water bodies leading to the formation of the diatomaceous Bioluminescence: Ability of the earth. organism to produce light.Noctiluca, y Desmids are present in large numbers in Peridinium emit light due to luciferin- non-polluted water. They are unicellular. luciferase reaction. Examples: Navicula, Cymbella, Triceratium. Euglenoids Characteristics Chrysophytes y Unicellular, found in freshwater body. Characteristics Euglena is an example. y It includes diatoms and desmids (golden Cell wall is absent. They are covered algae). Diatoms are microscopic and by a layer of protein known as pellicle single celled. They do not have flagella which makes them flexible. and float in water. y They consist of two flagella. One is short and other is long. Biological Classification 23. Chapter y Euglena shows mixotrophic nutrition. y They consist of flagella for locomotion. In the presence of sunlight, they are They only show asexual reproduction. autotrophic while in the absence of Examples: Trypanosoma gambiense, sunlight they obtain their food by Leishmania, Giardia. feeding on other organisms. y They reproduce asexually. Amoeboid Protozoans Examples: Euglena, Astasia. y Also known as Sarcodina. y They are found in fresh water or marine water. Rack your Brain y They show locomotion by finger like projections known as pseudopodia. What is hologamy? Which group of y Reproduction is usually asexual by organisms shows it? binary fission and some forms show sexual reproduction. Examples: Amoeba, Entamoeba Consumer – decomposer protists – histolytica slime moulds Characteristics Ciliated Protozoans y They are found in shady and damp y Also known as Ciliata, one of the most places. advanced groups. y The vegetative phase of the thallus is y They are usually found in fresh water free living. It consists of the protoplasm and show locomotion because of the in which the nuclei are suspended. presence of thousands of hair like y Mode of nutrition is saprophytic. structures all over the body, known as y They reproduce by the formation of cilia. spores on special structures known y They consist of cytostome by which the as sporangia. The spores germinate intake of food takes place. to form myxamoebae which form the y The nucleus shows dimorphism. There gametes. These gametes fuse together is a micronucleus and a macronucleus. to reproduce sexually. Micronucleus controls the reproduction y Examples: Physarium, Stemonitis. while macronucleus is vegetative. Examples: Paramecium, Podophyra. Protozoan Protista Characteristics Gray Matter Alert!!! y They are unicellular and heterotrophic. Biological Classification y They are divided into the following- Hemixis: Reorganisation process where the Flagellated Protozoan macronucleus breaks and forms y Commonly known as Zooflagellates. new macronuclei. It is observed y They are unicellular, heterotrophic. in Paramoecium caudatum, Paramoecium aurelia. 24.  Chapter y Chitin is present in their cell walls. It is a polymer of N-Acetyl Glucosamine. Exception- Oomycetes, in which cellulose occurs. y The mode of nutrition is heterotrophic as they lack chlorophyll. Food is stored in the form of glycogen. y They are saprophytic, parasitic and symbiotic. Gray Matter Alert!!! Smallest Fungi – Yeast Largest Fungi – Mycelium of Armillaria Sporozoans ostoyae or Honey fungus. y Simple body design. y They have a parasitic mode of nutrition. y They lack any organelle for locomotion. Saprophytic Fungi y They produce spores in their life cycle Saprophytic means they obtain their which causes infection. nutrition from dead decaying organic Example: Malaria causing Plasmodium matter. and Monocystis. Parasitic Fungi KINGDOM FUNGI y Parasitic means they obtain food from y It comprises eukaryotic organisms. living hosts. y It is divided into Phycomycetes, y Parasitic fungi may be obligate or Ascomycetes, Basidiomycetes and facultative. Deuteromycetes. ⚪ Obligate parasitic fungi depend on a living host throughout their life. Characteristics ⚪ Facultative parasitic fungi are the one y They are mostly filamentous, who are actually saprophytes and multicellular except Yeast which is have secondarily become parasites. unicellular. ⚪ Parasitic fungi form the structure y Body is not composed of stem, leaves appressoria to adhere to the host and and roots. It is composed of fine tubular Biological Classification for absorption of food haustoria are structures known as hyphae which produced by obligate parasitic fungi. form a network known as Mycelium. The mycelium may be septate or non- Symbiotic Fungi septate. When aseptate, the nuclei lie y Fungi show a symbiotic association with in a common mass and this condition is the algae and with the roots of higher known as coenocytic. 25. Chapter plants. Symbiotic association with the algae is known as Lichens. y In lichens, the fungi absorb water and minerals and algae synthesize food. The association of fungi with the roots of higher plants is known as mycorrhiza. Reproduction in Fungi Fig: Sporangiophore y Reproduction in fungi is vegetative, asexual and sexual. y In Yeast, the whole cell is converted Conidiospores or Conidia into a reproductive structure known as y In some fungi, the spores are not Holocarpic. produced in sporangium but at the y In Rhizopus, only a part of the thallus is tip of specialized branches known as converted into a reproductive structure, conidiophores. known as Eucarpic. y Such spores are known as conidiospores y Fungi reproduces vegetatively by or conidia. They are single celled, double fragmentation, budding, oidia and celled or multi celled. fission. y They are formed exogenously. Asexual Reproductive Units in Fungi Conidium Fungi reproduces asexually by- Zoospores y These are thin-walled spores that are motile due to the presence of flagella. The zoospore may be uniflagellate or Phialide biflagellate. Conidiophore Hyphae Fig: Conidiophore Biological Classification y Fungi reproduces sexually by the Sporangiospores following three phases- y These are thin walled, non–motile spores produced in sporangium. Plasmogamy- The fusion of the two y They are also called aplanospores. They motile or non-motile gametes leads to are formed endogenously. 26.  Chapter the fusion of their protoplast. The nuclei Spermatization do not fuse and the mycelium formed is y The male gametes called Spermatia are dikaryotic. formed in Spermogonia. Karyogamy- The fusion of the two y The female gametangium is called haploid nuclei from two different Ascogonium. parents results in the formation of a y The spermatium attaches itself to diploid nucleus. the trichogyne and the male nucleus Meiosis- Reductional division in the is transferred and thus causing zygote leads to the formation of haploid dikaryotization. spores. Karyogamy and meiosis occur in fungi Somatogamy but sometimes not at a specific time or y It occurs in higher fungi. Hyphae of two point in the life cycle. Such a cycle is different strains fuse together and bring known as the parasexual cycle and the about dikaryotization. phenomenon is known as parasexuality. It is seen in some of the Deuteromycetes. The fungi reproduce sexually by the following methods- Gametangial Contact y The fusion of two gametangia occurs. y The male gametangium is antheridium and the female gametangium is oogonium. y The male nucleus is transferred to the Mycorrhiza female directly or through a tube. y The term ‘mycorrhizae’ was coined by Frank (1885). Gametangial Copulation y It is an example of symbiosis or y In some cases, the whole thallus acts mutualism. as gametangium and in others, the y Association between a fungus and dissolution of the cell wall between the the root of the higher plants e.g., Pine, two gametangia is known as gametangial Birch, Ficus etc. Roots of higher plants copulation. get infected by fungi. The root cells and fungi directly transmit nutrients to each other. Biological Classification Definition Mycorrhiza: It is a symbiotic associa- tion between a fungus and the roots of a green plant. 27. Chapter Mycorrhiza is classified into two plants develop resistance to soil borne categories: diseases, drought resistance and pH y Ectotrophic mycorrhiza: and temperature extremes. ⚪ The fungus partner is commonly a On the basis of the mycelium, spore Basidiomycetes. formation and reproduction, the fungi ⚪ In this type of mycorrhiza, the are divided into the following divisions: fungus completely encloses the Phycomycetes: Commonly known as rootlet and penetrates into the cells Algal fungi because of their aquatic of root cortex. habitat and form of the thallus. ⚪ The hyphae in intercellular space form a network called Hartig Net. Characteristics: Ectotrophic mycorrhiza is found in Pines, y Mycelium is coenocytic. Spurs, Firs, Oaks, Beeches, Birches, y Asexual reproduction takes place by the Eucalyptus. formation of sporangia which in aquatic y Endotrophic mycorrhiza: conditions form zoospores. ⚪ The fungal partner is commonly Zygomycetes. Zygomycetes: Commonly known as ⚪ In this kind of mycorrhiza, the conjugation Fungi. fungus does not form an external Characteristics mantle but lives within the root y These are terrestrial fungi, which are both intracellularly as well as usually saprophytic. intercellularly. y The mycelium is aseptate and thus ⚪ The fungal hyphae develop some coenocytic. The hyphae are made up of special organs, called vesicles within chitin. the root cortical cells and are called y Motile spores are absent, and they Vesicular-Arbuscular Mycorrhiza reproduce asexually by producing (VAM). VAM helps in the absorption sporangiospores. Sporangiospores are of phosphate from soil. produced in specialized structures Endotrophic mycorrhiza is found in known as sporangia, developed on Orchid. the tip of special hyphae called sporangiophores. Advantages of mycorrhizal association y Sexually they reproduce by the special y The fungal hyphae increase the plant’s structures called gametangium. Male uptake of phosphorus from the soil. and female gametangium is formed. y Helps the host to absorb water The male and the female gametangium Biological Classification efficiently. form gametes which are multinucleate y The fungi produce various growth and known as coenogametes. Sexual promoting substances which help the reproduction occurs by gametangial plants to grow efficiently. copulation or conjugation. Thus, they y Due to phytotoxins released by fungi are known as conjugation fungi. in mycorrhizal association, the higher 28.  Chapter y After conjugation, a diploid spore Basidiomycetes (Commonly known as known as zygospores is formed. Due to Club fungi) the formation of Zygospore, the class is Characteristics known as Zygomycetes. Zygospore does y Large group, which are the best not form the new mycelium but forms decomposers of wood. They are able to germ sporangium. Germ sporangium degrade both lignin and cellulose. forms the meiospores called germ y Mycelium is of two types-primary and spores which germinate to give rise to secondary. the mycelium. y Primary mycelium consists of haploid Examples: Rhizopus, Mucor. cells while secondary mycelium consists of diploid cells. Septum has central Ascomycetes (Commonly known as Sac pores with barrel shaped outgrowths. fungi) Such a structure is known as dolipore. Characteristics Clamp connections are also present. y Unicellular (Yeast) to multicellular y Mycelium of different mating strains (Penicillium). come together to form a dikaryotic y They are saprophytic (Yeast), parasitic mycelium. This secondary mycelium (Penicillium) and those growing on dung bears the basidiocarp which produces known as coprophilous (Mucor mucedo). sexual spores (basidiospores) on a club- y Mycelium is branched and is septate. shaped structure called a basidium. y They reproduce asexually by conidia y Each basidium produces four spores produced on the conidiophores. on the tips of minute stalks called y They reproduce sexually by the formation sterigmata. It is this reproductive of ascospores, which are produced in structure (basidium) that gives the specially formed fruiting bodies called group its name. the ascus. Usually, eight ascospores are Examples: Agaricus campestris, Ustilago produced in the ascus. There are four tritici types of ascus- y Cleistothecium is a closed, globose ascocarp from which the ascospores are released, only by its rupture or decay. y Gymnothecium is a completely enclosed structure containing globose or pear-shaped, asci. The wall of the gymnothecium has loosely interwoven Biological Classification hyphae. y Perithecium- These are flask shaped structures opening by a pore or ostiole through which the ascospores escape. y Asexual reproduction takes place by the formation of conidia. Examples: Neurospora, Peziza 29. Chapter Biological Classification Fig: Asexual Cycle of Ascomycetes and Phycomycetes 30.  Chapter Harmful activities Rack your Brain y Aspergillus contaminates laboratory cultures thus known as ‘weed of What is the role of clamp connection laboratory’. It produces Aflatoxins that in Fungi? are carcinogenic. y Rhizopus and Mucor are the common saprotrophic fungi that attack a large Deuteromycetes: Commonly known as number of foodstuffs. ‘Fungi Imperfecti’ y Hallucination drug LSD i.e., Lysergic Characteristics Acid Diethylamide is extracted from y The group consists of all the fungi in Claviceps purpurea. which the sexual reproduction is not y They cause a number of diseases in the reported. plants- y Mycelium is septate and thus is not ⚪ Early Blight of Potato caused by coenocytic. Clamp connections are Alternaria solani. absent. ⚪ Red Rot of Sugarcane caused by y Asexual reproduction takes place by Colletotrichum falcatum. spores like conidia. ⚪ Tikka Disease of Ground Nut caused Examples: Alternaria solani, by Cercospora personata. Colletotrichum, Helminthosporium oryzae ⚪ Wilt of Arhar caused by Fusarium. ⚪ Ringworm/Athlete’s Foot caused by Economic Importance of Fungi Trichophyton interdigitale. Useful activities y Yeasts are commonly used for Rusts fermentation and in preparation of ⚪ These are characterized by the alcoholic beverages e.g., beer, wine, formation of rusty pustules cider, toddy etc. Two common yeasts containing the spores. A basidiocarp used in the brewing industry are is absent. (i) Puccinia graminis tritici Saccharomyces cerevisiae (Brewer’s causes black rust of wheat. ye