Microbiology Lecture 1 PDF

MICROBIOLOGY LECTURE NO 1 DR/ Mayada Mahmoud Lecturer of microbiology and immunology Researcher at HRI Branch manger of NFSA Risk assessor ( USAID and WHO) Dr. Mayada Mahmoud  What Is Microbiology? Microbiology is th...

MICROBIOLOGY LECTURE NO 1 DR/ Mayada Mahmoud Lecturer of microbiology and immunology Researcher at HRI Branch manger of NFSA Risk assessor ( USAID and WHO) Dr. Mayada Mahmoud  What Is Microbiology? Microbiology is the study of microorganisms – (biological entities too small to be seen with the naked eye). Microorganisms (or microbes) inhabit every corner of the Earth and are responsible for some of the deadliest human diseases and form the basis of many industrial processes. An object must measure about 100 micrometers (µm) to be visible without a microscope, but most microorganisms are many times smaller than that. Dr. Mayada Mahmoud Dr. Mayada Mahmoud  Types of Microorganisms A. Bacteria  Bacteria are found in nearly every habitat on earth, including within and on humans.  Most bacteria are harmless or helpful, but some are pathogens, causing disease in humans and other animals.  Bacteria are often described in terms of their general shape.  Common shapes include: spherical (coccus), rod-shaped (bacillus), or curved, wavy (spirillum), spiral (spirochete), or vibrio). Dr. Mayada Mahmoud B.Protists  Protists are unicellular eukaryotes that are not plants, animals, or fungi.  Algae and protozoa are examples of protists. Algae (singular: alga) Are plant-like protests that can be either unicellular or multicellular.  Their cells are surrounded by cell walls made of cellulose, a type of carbohydrate. Dr. Mayada Mahmoud Protozoa (singular: protozoan) :  Protozoa are very diverse.  Some protozoa are photosynthetic; others feed on organic material. Some are free-living, whereas others are parasitic, only able to survive by extracting nutrients from a host organism.  Most protozoa are harmless, but some are pathogens that can cause disease in animals or humans. Dr. Mayada Mahmoud  C. Fungi 1. Fungi (singular: fungus) are also eukaryotes. 2. Some multicellular fungi, such as mushrooms, resemble plants. 3. Some are pathogeneic. 4. Fungi are not photosynthetic, and their cell walls are usually made out of chitin rather than cellulose. 5. Unicellular fungi(yeasts) are included within the study of microbiology. ORAL CANDIDIASIS MUSHROOMS Dr. Mayada Mahmoud  E. Molds: 1. Molds are made up of long filaments that form visible colonies. 2. Molds are found in many different environments, from soil to rotting food. 3. Molds play a critical role in the decomposition of dead plants and animals. 4. Some molds can cause allergies, and others produce disease-causing metabolites called mycotoxins. 5. Molds have been used to make pharmaceuticals, including penicillin( blue green mold fungi), which is one of the most commonly prescribed antibiotics, and cyclosporine, used to prevent organ rejection following a transplant. Dr. Mayada Mahmoud G. Helminths Multicellular parasitic worms called helminths are not technically microorganisms, as most are large enough to see without a microscope. However, these worms fall within the field of microbiology because diseases caused by helminths involve microscopic eggs and larvae. Taenia saginata, infects both cattle and humans. T. saginata eggs are microscopic (around 50 µm), but adult worms like the one shown here can reach 4–10 m, residence in the digestive system. Dr. Mayada Mahmoud H. Viruses  Viruses are acellular microorganisms, which means they are not composed of cells.  A virus consists of proteins and genetic material—either DNA or RNA, but never both—that are inert outside of a host organism.  Viruses are incorporating themselves into a host cell to multiply and infect other hosts.  Viruses can infect all types of cells, from human cells to the cells of other microorganisms.  In humans, viruses are responsible for numerous diseases.  A bacteriophage is a virus that infects and replicates within bacteria and it is used as alternative to antibiotics. Dr. Mayada Mahmoud  Bacterial structure and organization The Cell : The cell can be defined as a basic functional unit of life perform their individual functions. All living organisms are composed of 1. One cell (single cell) which called uni-cellular organisms, like prokaryotic organisms including bacteria. 2. or many cells to(multi-cellular organisms), like eukaryotic organisms including human, animals and plants. Dr. Mayada Mahmoud  Types of Cells Prokaryotic Cell and Eukaryotic cells Dr. Mayada Mahmoud  Prokaryotic Cell vs Eukaryotic Cell Prokaryotic Cell Eukaryotic Cell The term “prokaryote” is derived from the Greek word The term “Eukaryotes” is derived from the Greek word “pro“, (meaning: before) and “karyon” (meaning: “eu“, (meaning: good) and “karyon” (meaning: kernel), kernel=Nut). It translates to “before nuclei.“ therefore, translating to “good or true very minute in size Fairly large in size Nuclear region (nucleoid) not surrounded by a Nuclear region (nucleoid) surrounded by a nuclear nuclear membrane membrane Single chromosome present More than one chromosome present Nucleolus absent Nucleolus present Similarities: Both have ribosomes, cytoplasm, and cell membrane Dr. Mayada Mahmoud Dr. Mayada Mahmoud  Inner structure Cytoplasm It is the storehouses for all types of chemicals and components that are used to sustain the life of a bacterium. Function : It helps in cellular growth, metabolism and replication. Cytoplasm region (or) nucleoid region An area of the cytoplasm that contains the single bacterial DNA molecule. Plasmids They are a small additional circle of DNA. Plasmid plays a vital role in exchanging DNA between the bacterial cells. Bacterial cells have many plasmids. Dr. Mayada Mahmoud Dr. Mayada Mahmoud  Inner structure (continue) Ribosome They are the smallest part of cell organelle. Function : Ribosome plays a vital role in protein synthesis. selective action of several antibiotics (tetracycline) that inhibit bacterial protein synthesis. Mesosomes: They are the folding, present inside the plasma membrane. Function Plays a vital role in cellular respirations, replication of DNA, cell division, separation of chromosomes during cell division and also performs the role of Golgi bodies and mitochondria. Dr. Mayada Mahmoud  Outer structure Capsule: It is composed of a thick polysaccharide which covers the outside of the cell wall. Function It is used to stick cells together and works as a food reserve and it also protects the cell from dryness and from chemicals. Slime layer An easily removed layer composed of polysaccharides. Function Serve to trap nutrients, to aid in cell motility, to bind cells together or to adhere to smooth surfaces. Some bacteria produce slime to help them to stick to surfaces , usually made up from polysaccharides, produced by streptococcus mutants enables stick to the surface of teeth, were helps to form plaque , leading to dental carries. Dr. Mayada Mahmoud  Outer structure Cell wall The bacteria are surrounding by rigid cell wall. cell wall consist of peptidoglycan. Peptidoglycan called murein Peptidoglycan (PG) is complex of polysaccharide and polypeptide. Function Protection the internal structures. It maintains the shape of bacterial cell. Contain component which toxic to host cell. It plays a role in cell division Example on cell wall deficient bacteria a- Mycoplasma This is naturally deficient in cell wall. Mycoplasma is not affected by penicillin treatment. b- L- forms Some of bacteria under certain condition are fail in synthesis of cell wall when the cells is subjected to penicillin drug or lysozymes. Dr. Mayada Mahmoud  Gram staining It differentiates between bacteria depending on the amount of peptidoglycan in the cell wall, in which bacterial species with walls containing small amounts of peptidoglycan and, characteristically, lipopolysaccharide, are Gram negative whereas bacteria with walls containing relatively large amounts of peptidoglycan and no lipopolysaccharide are Gram positive. Most bacteria are classified according to reaction of Gram stain into major groups; Gram positive & Gram negative bacteria based on staining properties. Dr. Mayada Mahmoud  Gram + ve VS Gram – ve bacteria Gram + ve Gram – ve Relatively thick layer of peptidoglycan Have only a thin layer of peptidoglycan Retain crystal violet dye in Gram staining procedure; Appear pink so appear purple Dr. Mayada Mahmoud Dr. Mayada Mahmoud  Cell membrane (plasma membrane):- Plasma membrane Referred to as phospholipid bilayer; composed of lipids and associated proteins. Function 1. Control on inflow of metabolites from cell by control on active transport of molecules into cell because it has selective permeability. 2. Energy generation. 3. Secretion of enzyme and toxin. 4. Have important role in synthesis of cell wall. Dr. Mayada Mahmoud  External structure (continue) Flagella Present in some prokaryotic cells Composed of filament, hook, and basal body Flagellin protein Function used for locomotion (responsible for movement) Bacteria move in response to stimuli (taxis). Fimbriae and Pili Rod-like protein extensions, Sticky, bristle like projections composed of protein called pilin Shorter than flagella and May be hundreds per cell Function: Used by bacteria to adhere to one another, to hosts, and to substances in environment Serve an important function in biofilms(The plaque that forms on your teeth and causes tooth decay is one type of bacterial biofilm) Mediate the transfer of DNA from one cellDr. to another Mayada Mahmoud (conjugation). Spores Some bacteria can develop a highly resistant structure called endospore as response to unfavorable growth environmental condition such as radiation , heat for ex., Clostridium , Bacillus. Endospore formation is NOT a mechanism of reproduction. Rather it is a mechanism for survival It is impermeable to water. Spores may vary in : -Shape : oval or spherical. -Site : terminal , sub terminal or central as seen. -Size : the same size or bulging of the vegetative cell. Dr. Mayada Mahmoud