Unit 3- Classification and Characteristics of Microorganism PDF

Unit 3: Classification & Characteristics of microbes Presented by: Ms Muhongo  Learning objectives By the end of this unit, the students should be able to : ❖Identify the types of microorganism ❖List the classification of microorganism ❖Identify characteristics of d...

Unit 3: Classification & Characteristics of microbes Presented by: Ms Muhongo  Learning objectives By the end of this unit, the students should be able to : ❖Identify the types of microorganism ❖List the classification of microorganism ❖Identify characteristics of diseases causing microorganisms  Binomial System Is a system for naming organisms using two names: the genus name and the specific epithet name. It was introduced by Carl Linnaeus in the 18th century and is used to ensure each species has a unique and universally recognized name. Genus: First part of the name, capitalized. Specific epithet: Second part of the name, lowercase. Together they form the species name.  Binomial System rules ❖Binomial names are italicized (or underlined when handwritten). ❖Genus Abbreviation: After the first mention, the genus can be abbreviated to its initial (e.g. K. pneumoniae). ❖Names are usually in Latin or Latinized to maintain consistency across languages. CLASSIFICATION OF ORGANISMS  The domain system Three domain systems are: ❖ Two domain of prokaryotes (archaea and bacteria) ❖ One domain of eukarya  The Kingdom Five kingdoms 1. Prokaryotae (monera)- Bacteria and archaea 2. Protista- Algae and protozoa 3. Fungi- fungi 4. Plantae- plants 5. Animalia- animals  Microorganisms/Microbes ❑ Organisms that can only be seen under a microscope ❑ Classified as: ✓ Pathogenic: disease causing microbes ✓ Non-pathogenic- none disease causing microbes ❑ They can be either: based on cells ✓ Unicellular ✓ Multicellular TYPES OF MICROORGANISMS ❖Bacteria ❖Viruses ❖Fungi ❖Algae ❖Archaea ❖Parasites (protozoa and microbial metazoa) ❖Rickettsia Classification of Bacteria Bacteria can be classified and identified using the following characteristics: ✓ Distinctive morphology (shapes). ✓ Gram staining ✓ Oxygen requirement ✓ Flagella ✓ Nutrition ✓ Temperature ✓ Formation of endospores  Morphology (shapes) of Bacteria: ❖With the compound light microscope, the size, shape, and morphologic arrangement of various bacteria are easily observed. ❖There are three basic shapes of bacteria Cocci- round or Spherical bacteria Bacilli- rod-shaped bacteria Spirilla- Curved and Spiral-shaped bacteria.  Cocci/ Coccus: oUsually round/ oval when reproducing cells can remain attached to each other. ❖ Can form different types of grouping: Diplococcus (they lie in pairs) e.g Streptococcus pneumonia, gonococcus, meningococcus Streptococcus (they lie in chains)- also pathogenic Streptococcus pyrogens. Tetradcoccus (group of four) e.g. micrococcus sp. Sarcinae (group of 8) e.g sarcina ventriculi Staphylococci (Grape like cluster) e.g Staphylococcus aureus Bacillus/ Bacilli Rodlike They divide in : ❖ Bacilli (one) ❖ Diplobacilli (pair) ❖ Streptobacilli (long chain) ❖ Coccobacilli (Shape between a cocci and bacilli) Spirilla ❖They are spiral Can be in 3 forms: ❖Spirillum (rigged spiral) e.g Helicobacter pylori ❖ Spirochete (flexible spiral) e.g Treponema pallidum ❖ Vibrio (rod shape with a curve) e.g Vibrio cholera  Cell wall structure Classification based on peptidoglycan molecule in the Cell wall as: ▪ Gram-positive- thick peptidoglycan ▪ Gram-negative- thin peptidoglycan  Staining reaction ❖Most bacteria are colourless, transparent, and are difficult to see ❖Therefore, various staining methods developed to enable scientists to see and examine bacteria ❖In preparation for staining, the bacteria are smeared onto a glass microscope slide (smear), air-dried, and then fixed, ❖Specific stains and staining techniques are used to observe bacterial cell (e.g. size, shape, morphologic arrangement, composition of cell wall, capsules, flagella, endospores) 16  Method of fixation ❖Fixation is a process used in microbiology to preserve the structure and composition of cells and tissues for subsequent staining and microscopic examination. ❖There are two most common method of fixation, Heat fixation Alcohol (methanol) fixation 17  Purpose of fixation ❖Fixation serves three purposes: Kills the organisms: This prevents further metabolic activity and ensures that the microorganisms remain in a fixed state. Preserves their morphology: Fixation helps maintain the original shape and structure of the cells and tissues. Anchors the smear to the slide: This prevents the specimen from being washed away during subsequent staining and examination. 10/3/2024 WU 18  Types of staining reaction ❖Simple staining- used to determine bacterial shape (e.g., cocci, bacilli) and morphologic arrangement (e.g., chains, clusters). ❖Structural staining - Used to observe specific structures within bacteria like capsules, spores, and flagella ❖Gram staining- is a differential staining used to differentiate between different types of bacteria based on their cell wall characteristics. It categorizes bacteria into two groups: Gram-positive and Gram-negative. 10/3/2024 WU 19  Gram staining Based on the results of Gram staining method, bacteria are classified as ❖Gram negative- stain red or eosin in colour under a microscope ❖Gram positive- stain purple or violet in colour under a microscope ▪ The peptidoglycan molecule in their cell wall is the one gets stained. Gram Staining procedures  Interpretation of Gram Staining results ❖Gram-positive bacteria - The thick layer of Peptidoglycans is stained purple by the crystal violet dye, which is why gram-positive bacteria appear purple or violet. ❖Gram-negative bacteria - The thin layer of Peptidoglycans cannot retain the crystal violet dye, and thus appear red or pink due to the retention of the counter-stain. Gram stain examples  Motility ❖Bacterial motility is most associated with the presence of flagella or axial filaments, ❖A flagella stain can be used to demonstrate the presence, number, and location of flagella on bacteria cells. 10/3/2024 WU 24  Colony morphology ❖A mound or pile of bacteria on the surface of a solid culture medium is known as a bacterial colony, ❖ The colony morphology of bacteria varies from one species to another, this include the; Size, Colour, Overall shape, Elevation, Margin of the colony. WU 25  Oxygen requirement Bacteria are also classified based on the requirement of oxygen for their survival ❖Obligate Aerobic bacteria - Bacteria that need oxygen for their survival. ❖Obligate Anaerobic bacteria - Bacteria that do not require oxygen for survival. ❖Facultative anaerobe-are capable of surviving in either the presence or absence of oxygen. ❖Microaerophiles- Requires low concentration of Oxygen  Temperature requirement Classification based on temperature response: ❖Psychrophiles- those that grow in cold temperature e.g. at -20 to 10 °C. ❖Mesophiles- those that grow at optimum temperature e.g. at 20-40 °C. ❖Thermophiles- those that grow in hot temperature e.g. from 45-122 °C.  Nutritional Requirements ❖All bacteria need some essential elements such as carbon, hydrogen, oxygen, sulphur, phosphorus, and nitrogen for growth. ❖Some bacteria require additional elements like potassium, calcium, iron, manganese, magnesium, cobalt, copper, zinc, and uranium. ❖Certain microbes have specific vitamin requirements. ❖Fastidious organisms: Bacteria with high nutritional demands are called fastidious. 10/3/2024 WU 28  Nutrition requirement ❖Photoautotrophic Bacteria They synthesize their own food from organic matter, light energy and carbon-dioxide. ❖ Autotrophy/ Chemoautotrophic Bacteria They synthesize their food with the help of energy obtained from chemical sources. ❖ Heterotrophic Bacteria They obtain their food from other living organisms, as they cannot synthesize it on their own. ❖Symbiotic Bacteria They obtain nutrition from host organism by offering something in return ❖Saprophytes Bacteria They use decaying life form as source of energy  Biochemical and Metabolic Activities ❖As bacteria grow, they produce many waste products and secretions, some of which are enzymes that enable them to invade their host and cause disease. ❖The pathogenic strains of many bacteria, such as staphylococci and streptococci, can be identified by the enzymes they secrete. 10/3/2024 WU 30  Viruses Are also called virions Are very small and simple in structure Their size range from 10 to 300nm in diameter They can only be observed/ viewed using atomic microscope They infect all organism includes human, animals, fungi, protozoa, algae, and bacterial cells. Five specific properties that distinguish viruses from living cells ❖The viruses posses either DNA or RNA unlike living cells which posses both. ❖ They are unable to replicate on their own, they require a host cell. ❖ Unlike other cells, they do not divide by binary fission, mitosis or meiosis ❖They lack genes and enzymes necessary for energy production ❖ They depend on the ribosomes, enzymes and metabolites of the host protein and nucleic acid production.  Virion structure ❖A typical virion consists of a genome of either DNA or RNA, surrounded by a capsid (protein coat), composed of many small protein units called capsomeres (capsomers) ❖Together, nucleic acid and the capsid referred to as nucleocapsid ❖Some viruses (called enveloped viruses) have outer envelope composed of lipids and polysaccharides ❖There are no ribosomes for protein synthesis or sites of energy production; they invade and take over functioning cell to produce new virus. 10/3/2024 WU 33  Viruses classified by the following characteristics: Type of genetic material (either DNA or RNA) Shape of the capsid Number of capsomeres, Size of the capsid, Presence or absence of an envelope, Type of host that infects, Type of disease it cause, Target cell, and Immunologic or antigenic properties. 10/3/2024 WU 34  Categories of viruses; ❖ Based on types of genome they posses Most viruses either double- stranded DNA, or single-stranded RNA Few viruses possess single- stranded DNA, or double-stranded RNA ❖ Viral genomes usually circular molecules, ❖ Some are linear (have two ends) 10/3/2024 WU 35  Morphology Classification based on the shape: ▪ Helical viruses- Have filamentous ▪ Polyhedral viruses- they have isometric ▪ Spherical viruses- they are enveloped ▪ Complex viruses- have head and tail  Viroid's and prions ❖Although viruses are extremely small non-living infectious agents, ❖viroid's and prions are even smaller and less complex infectious agents. ❖Viroid's are infectious RNA molecules that cause a variety of plant disease ❖Prions are infectious protein molecules that cause a variety of animal and human diseases 10/3/2024 WU 37  INFECTIOUS CYCLE OF VIRUSES There are various ways how the viral genome enters the host cell and how mature virions leave the host ❖Lytic pathway ❖Lysogenic pathway. 10/3/2024 WU 38  The Lytic pathway cycle 10/3/2024 WU 39  The Lysogenic pathway cycle 10/3/2024 WU 40  VIRAL PATHOGENESIS The ability of viruses to cause disease can be viewed on two levels Cellular level- Changes that occur within individual cell. Viruses can disrupt various cellular processes Host level- Process that take place in the infected patient. Viral infections can cause a range of symptoms and systemic effects, depending on the virus and the host's response like fever, headache etc 10/3/2024 WU 41  Viral Effects on Infected Cells Infected cells can exhibit various morphological and functional changes, including: ❖Multinucleated giant cells: These are formed when multiple cells fuse together after infection with certain viruses, such as herpesvirus and respiratory syncytial virus. ❖Cytopathic effect (CPE): This refers to visible or functional changes in infected cells, often associated with cell death. Like cells shrinks or bust ❖Malignant transformation: In some cases, viral infection can lead to the transformation of cells into a malignant state, characterized by uncontrolled growth and the ability to invade surrounding tissues. ❖Asymptomatic infection: Some virus-infected cells may appear normal and function normally, despite producing large numbers of progeny viruses. This is known as latent infection or persistent infection. 10/3/2024 WU 42 Viral effect on infected person ❖Viral infections can cause a wide range of symptoms and effects in infected patients. ❖These effects can vary depending on the specific virus, the host's immune response, and other factors. Some common viral effects include: ❖Respiratory symptoms: Cough, sneezing, shortness of breath, sore throat, chest pain ❖Gastrointestinal symptoms: Diarrhea, vomiting, nausea, abdominal pain ❖Neurological symptoms: Headache, fever, fatigue, muscle aches, confusion, seizures ❖Other symptoms: Rash, fever, weight loss, fatigue, weakness ❖Severe complications: Pneumonia, meningitis, encephalitis, liver damage, kidney failure, death 10/3/2024 WU 43  Viral Pathogenesis and immunopathogenesis Viral diseases can cause symptoms through two primary mechanisms: ❖Direct cell damage- Viruses can cause cell death and dysfunction. This can lead to loss of function in infected tissues and organs. For example, poliovirus kills neurons, resulting in paralysis, while other viruses may impair cellular functions without causing immediate death. ❖Immunopathogenesis- occurs when the immune system's response to a viral infection causes tissue damage and symptoms. One example is the action of cytotoxic T cells, which can kill virus-infected cells, leading to potential tissue damage. 10/3/2024 WU 44  Viral virulence ❖Viral virulence can vary significantly between different viruses and even among strains of the same virus. This variation is influenced by factors such as: ❖Viral genetics: The genetic makeup of a virus can determine its ability to replicate, spread, and cause disease. ❖Host factors: The health status, age, and genetics of the host can influence the severity of a viral infection. ❖Environmental factors: Factors like temperature, humidity, and sanitation can affect the transmission and spread of viruses. 10/3/2024 WU 45  Viral virulence and evasion of host defense ❖Viruses have evolved various strategies to evade host defenses, including: ❖Producing multiple antigens: Viruses can produce a large number of different antigens, making it difficult for the immune system to recognize and target them all. ❖Reducing the synthesis of class I MHC proteins: MHC proteins are essential for presenting viral antigens to cytotoxic T cells. By reducing the production of MHC proteins, viruses can impair the ability of cytotoxic T cells to recognize and kill infected cells. 10/3/2024 WU 46  The duration of viral infections ❖Acute infections: These are infections that have a rapid onset and relatively short duration, typically lasting a few days to a few weeks. Examples include the common cold, influenza, and most cases of gastroenteritis. ❖Chronic infections: These are infections that persist for a long period, often for months or years. Examples include hepatitis B, hepatitis C, and HIV. ❖Latent infections: These are infections in which the virus remains dormant in the host's cells, without causing active symptoms. They can reactivate at a later time, leading to a recurrence of the infection. Examples include herpes simplex virus 10/3/2024 WU 47  Fungi ❖Mycology is the scientific study of fungi, and a person who studies fungi is called a mycologist. ❖Fungi are ubiquitous organisms found in various environments. They can be saprophytic (living on dead organic matter), or parasitic, causing diseases in other organisms. Examples of parasitic fungi include ringworm, and fungal infections of the lungs. ❖Fungi can be both harmful and beneficial ❖Fungi are a diverse group of eukaryotic organisms that include yeast, molds etc. ❖Fungi are often referred to as the "vultures of the microbial world" due to their ability to decompose organic matter and recycle nutrients. They play a vital role in maintaining the balance of ecosystems. 10/3/2024 WU 48  Classification of fungi- The kingdom fungi ❖The kingdom Fungi is currently divided into five phyla based primarily on their mode of sexual reproduction: Lower Fungi: 1. Zygomycotina (Zygomycota):Includes common bread molds and other fungi that cause food spoilage. Characterized by the formation of zygospores during sexual reproduction. 2. Chytridiomycotina (Chytridiomycota):Considered to be "not true fungi" due to their flagellated spores. Primarily aquatic organisms, often found in water or soil Higher fungi: 3. Ascomycotina (Ascomycota): Includes certain yeasts and some fungi that cause plant diseases. Characterized by the formation of ascospores within structures called asci. 4. Basidiomycotina (Basidiomycota): Includes some yeasts, some fungi that cause plant diseases, and the large "fleshy fungi" found in woods (e.g., mushrooms).Characterized by the formation of basidiospores on structures called basidia. 5. Deuteromyotina (Deuteromyota): Also known as "imperfect fungi" due to their lack of observed sexual reproduction. Includes many medically important molds, such as Aspergillus and Penicillium 10/3/2024 WU 49  Algae ❖Are photosynthetic, eukaryotic organisms, together with protozoa, are classified in second kingdom of five-kingdom system of classification ❖The study of algae is called phycology or (algology) ❖A person study algae is called phycologist or (algologist) ❖All algal cells consist of; cytoplasm, Cell wall, Cell membrane, Nucleus, plastids, ribosome, mitochondria, and Golgi bodies ❖Some algae cells have pellicle (thickened cell membrane) stigma (light sensing organelle (eyespot) and flagella ❖Algae are more plantlike than protozoa, ❖Not all algae are microorganisms, they are found fresh water, salt water, in wet soil, and wet rocks ❖They produce their energy by photosynthesis 10/3/2024 WU 50  Algae Found in fresh water and salty water, wet soil, and on wet rocks. Few species use organic nutrients and others survive with very little sunlight. classified based on photosynthetic pigments as: green, golden, brown or red algae  Archaea ❖Archaea, mean an ancient ❖Archaea contains 2 phyla, 8 classes, 12 orders, 21 families 69 genera and 217 species ❖They vary in shape, some are cocci, bacilli, and other form long filaments ❖Many are extremophiles, meaning they live in extreme environment. ❖All archaea possess cell walls, their cell walls contain no peptidoglycan as in case of all bacteria 10/3/2024 WU 52  OTHER MICROORGANISMS Chlamydia's, rickettsia's and mycoplasmas ❖ Are bacteria, but do not possess all the features of a typical bacterial cells. ❖ Referred to as unique or obligate intracellular bacteria. ❖ As they are small and difficult to isolate.  Rickettsia’s ❖Bacteria with gram negative type cell wall. ❖ Obligated intracellular pathogens that cause diseases in human and other animals. ❖ The pathogen live within the host cell. ❖ Rickettsia have no connection to the disease called rickets. ❖They have leaky cell membranes, ❖ Most rickettsia must live inside another cell to retain all necessary cellular substances. ❖ All diseases caused by rickettsia species are transmitted by arthropod vectors (carriers) mainly ticks and lice.  Rickettsia’s ❖Arthropods such as lice, fleas, and ticks transmit the pathogen from one host to another by their bites or waste products. ❖Diseases includes typhus and typhus like diseases (e.g rocky mountain spotted fever) ❖ All these diseases involve production of a rash.  Chlamydia’s ❖They are obligated intracellular pathogens that cause diseases in human and other animals. ❖ The pathogen live within the host cell. ❖ Transferred by aerosols or by direct contact between host ❖ Not by arthropods Mycoplasmas ❖The smallest of the cellular microbes. ❖ Because they lack cell wall, they assume many shapes, from coccoid to filamentous ❖ Appear pleomorphic when examined microscopically. ❖ Sometimes confused with cell wall deficient (CWD) forms of bacteria.  Parasites Classified based on Location in/ on the Host 1. Ectoparasites: Parasites that live on the surface of the host (e.g. lice, mite, ticks…) 2. Endoparasites: Parasites that live inside the host (e.g. Giardia lamblia, Ascaris lumbricoides etc.) HOST ❖HOST: Organism that harbours the parasite and provides shelter and nourishment. TYPES 1. Definitive host 2. Intermediate host 3. Reservoir host 4. Amplifier host 5. Paratenic host  Types of Host ❖Definitive host: is essential for the completion of a parasite's life cycle, as its where the parasite reproduces sexually.E.g.: In Plasmodium sexual reproduction takes place in mosquitoes, MOSQUIOTO is the definitve host. ❖Intermediate host: is necessary for the development of the parasite's larval or asexual stages. E.g. In Plasmodium asexual multiplication takes place in human beings, thus humans are Intermediate host. ❖Reservoir host: can maintain the parasite's population and act as a source of infection for humans and other animals.. Eg: dog for Cystic echinococcosis. ❖Amplifier host: allow parasites to multiply rapidly, increasing the risk of transmission. ❖Paratenic host: is not essential for the parasite's life cycle, but they can serve as a temporary reservoir for the parasite.. Eg: big fish for plerocercoid larva of Diphyllobothrium latum  CLASSIFICATION OF PARASITE They are divided into two categories based on structure and shape: ❖Protozoa: Single-celled organisms, such as amoebas, ciliates, flagellates, and sporozoans. ❖Metazoa or Helminths (worms): Multicellular organisms, including flatworms (tapeworms and flukes) and roundworms. PROTOZOA ❖Protozoa are eukaryotic organisms ❖Study of protozoa is called protozoology ❖A person who studied protozoa is called a protozoologist. ❖Most protozoa are unicellular (single-celled). ❖Protozoal cells are more animal-like than plant-like. ❖Most of them are free-living organisms, found in soil and water. ❖All protozoa cell possess a variety of eukaryotic structures and organelles PROTOZOA ❖They have no chlorophyll, so they cannot make their own food by photosynthesis. ❖Some ingest algae, yeasts, bacteria and small protozoa as food. ❖Others live on dead and decaying organic matters.  A life cycle of Protozoa.. A typical protozoa life cycle consist of two stages: The trophozoite – is a motile, feeding, dividing stage The cyst stage - is the non-motile, dormant, survival stage.  CLASSIFICATION OF PROTOZOA Protozoa can be classified by their mode of locomotion 1. Amebae move by means of pseudopodia e.g. Entamoeba histolytica, Naegleria fowleri.. 2. Flagellates move by means of whip-like flagella e.g. Giardia lamblia, Trichomonas vaginalis 3. Sporozoa are non-motile, transmitted by a vector e.g. Plasmodium spp, Cryptosporidium spp 4. Ciliates move by means of hairlike cilia e.g. Balantidium coli  HELMINTHES/METAZOA ❖A multicellular organism, the main group being helminthes ( worms). ❖Helminths (parasitic worms) are divided into roundworms (nematodes) and flatworms. ❖Flatworms are further divided into tapeworms (cestodes) and flukes (trematodes).  Cestodes (tapeworms) ❖They are flatworms that are characterized by their long, segmented bodies. ❖Cestodes are intestinal parasites that attach and causes Taeniasis. Examples of various species: ❖Taenia saginata –beef tapeworm ❖ Taenia solium –pork tapeworm ❖ Taenia echinococcus – dog tapeworm ❖ Taenia gageri – goat tapeworm ❖ Taenia ovis – sheep tapeworm ❖ Diphylobothrium latum – fish tapeworm  Trematodes (Flukes) ❖They are parasitic organisms that infect various organs in their hosts, including the liver, lungs, intestines, and blood vessels. Common Types of Flukes: ❖Liver flukes: E.g. Fasciola hepatica (common liver fluke). ❖Lung flukes: E.g. Paragonimus westermani. ❖Intestinal flukes: E.g. Fasciolopsis buski (giant intestinal fluke) ❖Blood flukes: E.g. Schistosoma mansoni, Schistosoma haematobium, and Schistosoma japonicum  Nematodes ( roundworms) Common Types of Nematodes: ❖Intestinal nematodes: These nematodes infect the intestines. Examples include Ascaris lumbricoides (roundworm), Ancylostoma duodenale (hookworm), and Strongyloides stercoralis (threadworm). ❖Tissue nematodes: These nematodes migrate to various tissues in the body. Examples include Trichinella spiralis (trichina worm), Onchocerca volvulus (river blindness worm), and Wuchereria bancrofti (filarial worm).  Characteristics of disease-causing microorganisms Disease causing microorganism (pathogens) possess specific characteristics that enable them to invade and harm their hosts. These characteristics include: ❖Pathogenicity ❖Virulence ❖Organism specificity ❖Toxigenicity ❖Infectious dose ❖Antigenic variations ❖Ability to develop resistance 10/3/2024 WU 70  Characteristics of disease-causing microorganisms ❖Pathogenicity- refers to a microorganism's ability to cause disease in a host. This involves the microorganism's ability to invade the host, multiply, and produce harmful effects. ❖Virulence- is a measure of the severity of a disease caused by a pathogen. It refers to the degree of damage that a pathogen can inflict on a host. It's influenced by factors such as the number of pathogens a host encounters, the route and duration of exposure, and the pathogen's toxic capabilities. ❖Toxigenicity- is the ability of a microorganism to produce toxins. Toxins are substances that can damage host cells and tissues, contributing to the pathogen's virulence. 10/3/2024 WU 71  Characteristics of disease-causing microorganisms Infectious dose- The amount of pathogen ( number of microorganisms) required to cause an infection in the host. Antigenic variations- is a mechanism by which microorganisms can evade the host's immune system by changing or altering their surface antigens. Ability to develop resistance- Occur when a microbe acquire a genetic mutation. Making it resistant to the effect of one or more antimicrobial agents that were once exposed to. 10/3/2024 WU 72  Microbial growth ❖Microbial growth deals with the growth of a population (or an increase in the number of cells), not to an increase in the size of the individual cell. Factors involved in microbial growth: ❖Growth factors- conditions required by microorganisms to grow and reproduce ❖Inhibiting factors- condition required to stop the growth of microorganism 2024/10/03 73  MICROBIAL GROWTH FACTORS ❖ MOISTURE All organisms in the vegetative state require moisture for survival and their growth. ❖ NUTRIENTS- Organisms require organic and inorganic material such protein CHO Lipids – iron copper zinc etc. ❖ OXYGEN - Some microbes only thrive where is oxygen (Anaerobic) ❖ TEMPERATURE: Different microorganisms requires different temperatures ❖ pH – Different microorganisms requires different pH. ❖ OSMOTIC PRESSURE: If the microbe is to survive in environment which is always liquid it will be determined by the osmotic pressure.  Pathogenicity Many pathogens are able to cause disease because they possess one or all of the following: ❖Capsules ❖Pili ❖Endotoxin ❖secrete exotoxins and exoenzymes that damage cells and tissues. 10/3/2024 WU 75  Genetic Composition ❖Modern laboratories are increasingly relying on molecular diagnostic procedures to identify microorganisms. ❖These techniques analyze the genetic material (DNA or RNA) of an organism, which is unique to each species. ❖This allows for highly accurate and specific identification of microbes. ❖These techniques have revolutionized microbiology, enabling rapid and precise identification of pathogens, which is crucial for diagnosing and treating infectious diseases. 10/3/2024 WU 76  Genetics ❖Genetics is the study of heredity and involves topics such as DNA, genes, genetic codes, and chromosomes. ❖Genotype: its complete set of genes of an organism, which is inherited from its parents. ❖Phenotype: An organism's phenotype is the observable physical traits, attributes, or characteristics that result from the interaction of its genotype with its environment. ❖Genes: are segments of DNA that code for specific proteins or RNA molecules. They determine an organism's inherited traits. ❖Genetic code: is the set of rules that govern how DNA sequences are translated into amino acid sequences in proteins. ❖Genes play a crucial role in directing all cellular functions, providing an organism with its unique traits and individuality. 10/3/2024 WU 77  Microbial genetics ❖Microbial genetics is the study of the genetic material of microorganisms Involve key aspect such as: ❖Genome structure: The arrangement and organization of genetic material. ❖Gene expression: How genetic information is converted into functional products. ❖Genetic variation: Mechanisms that create diversity, like mutation and horizontal gene transfer. ❖Horizontal gene transfer: The transfer of genes between different organisms. ❖Genomic analysis: Studying the entire genetic makeup of a microorganism. 10/3/2024 WU 78  Genetic Mutations ❖Mutation- is a change in the DNA sequence of a gene. It can occur accidentally or be induced by exposure to certain agents. Mutations can be transmitted to offspring, leading to genetic variation within a population. Types of Mutations ❖Beneficial mutations: These mutations can provide an organism with an advantage, such as increased resistance to disease or improved ability to obtain resources. ❖Harmful mutations: These mutations can result in the production of non-functional proteins or disrupt essential cellular processes, leading to negative consequences for the organism. ❖Lethal mutations: These mutations can be fatal to an organism, preventing it from surviving or reproducing. 10/3/2024 WU 79  Genetic Mutations ❖The mutation rate- is the frequency at which mutations occur in a population. It can be influenced by various factors, including: Genetic factors: Some organisms may have higher or lower mutation rates due to their genetic makeup. Environmental factors: Exposure to mutagens, such as radiation or chemicals, can increase the mutation rate. ❖Mutagens are agents that can cause mutations by damaging DNA. 10/3/2024 WU 80  Mutations 10/3/2024 WU 81 Thank you