L1 Micro-BMS Lecture Notes PDF

INTRODUCTION Cellular Microorganism 1-Eukaryotes 2- Prokaryotes *Viruses *Prions Date of the lecture :21-11-2023 Microbiology department L1 in BMS module Dr :Amany Mohamed Abdel Wahab Professor of Microbilogy [email protected] ILOs The students must be -Diffe...

INTRODUCTION Cellular Microorganism 1-Eukaryotes 2- Prokaryotes *Viruses *Prions Date of the lecture :21-11-2023 Microbiology department L1 in BMS module Dr :Amany Mohamed Abdel Wahab Professor of Microbilogy [email protected] ILOs The students must be -Differentiate between eukaryotic and prokaryotic cells. -Describe the structures of bacterial cells &their functions. -Explain the different virulence factors in bacteria that allow it to produce the diseases.  Eukaryotic cell Prokaryotic cell --- --- Nuclear membrane + Nuclealus _____ + Chromosomes one More than one No except Mycoplasma Cytoplasmic membrane Contains sterols Mesosomes ___ + ____ + Mitochondria Ribosomes 70S 80S Reproduction Sexually or asexually Asexually by simple binary Fission Protozoa , Fungi , Human and Bacteria , Rickettsia eg animal cell CLASSIFICATION It is the arrangement of bacteria into taxonomic groups The taxonomic groups used in classification are (in diminshing size ) : are orders , families , genera and species. A group of organisms that have a Species :close 1- phenotypic resemblances determined by a number of biochemical tests, or 2- A group of organisms with genetic similarity. - Species can be divided into Subspecies and types by different methods of typing NOMENCLATURE Is the scientific naming of microorganisms bacteria named binomially By incorporating the genus and the species names. e.g Staphylococcus aureus The genus name The species name Streptococcus viridans The genus name The species name BACTERIAL MORPHOLOGY Morphological characters includes : - Size. - Shape. - Staining properties. - Arrangement. - Motility. - Sporulation. - Capsule. Size : micron SHAPE & ARRANGEMENT  Cocci  Bacilli BACTERIAL STRUCTURE NOMENCLATURE CELL WALL G+ve - Petidoglycan 50-60 % - Teichoic acid + Teichouronic acid + Polysaccharide G-ve - Petidoglycan 5-10 % -Lipoprotein layer. -Outer membrane. - LPS Periplasmic space NOMENCLATURE FUNCTION OF CELL WALL - Characteristic shape. - Protects cell membrane from external hypotonicity. - Responsible for gram stain. - Surface Ag - Endotoxin activity of G-ve bacteria BACTERIA WITH DEFICIENT CELL WALL - Mycoplasma pleomorphic penicillin x - L form environmental conditions - Protoplast G+ve Hypertonic medium - Spheroplast G-ve Hypertonic medium Choose the correct answer: 1-The cell walls of many Gram positive bacteria can be easily destroyed by the enzyme known as A-Lipase. B-Lysozyme. C-Pectinase. D-Peroxidase. CELL MEMBRANE - Semipermeable membrane. - Formed of 2 layers of phospholipids + proteins + enzymes. - Function: 1- Selective permeability. 2- Active transport of nutrients. 3- Provides enzymes needed for cell wall synthesis. 4- Plays a role in DNA replication. 5- Site of respiration ( energy ). Mesosomes Cell division and respiration. INTRACYTOPLASMIC STRUCTURES 1- The nuclear body: double stranded DNA. 2- Ribosomes: ptn + RNA Bacteria ribosomes: 70s sedementation rate 30S + 50S subunits : protein synthesis. 3- Plasmids : circular extrachromosomal DNA. 4- Intracytoplasmic inclusions : food reserves. SURFACE STRUCTURES Capsule - Polysaccaride except : B. anthracis : polypeptide Streptococcus pyogenes : hyaluronic acid - By gram stain : unstained hallow - Stained by special stain. Function: 1- Antiphagocytosis 2- Antigenic ( identification , typing ) Glycocalyx Polysaccaride lying outside the cell. - Function : adherence on surfaces. - e.g : S. mutans ( dental caries ) Choose the correct answer: Which of the following is true about the Cell wall of Gram positive bacteria (a) Cell wall comprises of four layers. (b) The cell wall is thicker than that associated gram-negative bacteria. (c) Cell wall devoid of teichoic acids. (d) Cell wall contain lipopolysaccharide layer. Flagellae - Organ of motility. - Formed of ptn flagellin. - Consists of a filament , a hook , basel body. - Anchored to cell membrane. Distribution: A- Monotrichate B- Lophotrichate. C- Amphitrichate. D- Peritrichate. Pili ( fimbriae ) - Hair-like projection: shorter + thinner - Formed of Ptn pilin. - Mainly in G-ve. 1- ordinary pili : attachement to mm. 2- Sex pili : with F + plasmid – transfere of DNA from F+ to F- bacteria ( conjugation ) Endospores: - Highly resistant resting form ( dormant) during unsuitable growth condition. - Usually outside the host tissues. - It is formed of nuclear material( core) + thick covering cortex + outer coat ( Ca++ impermeable to water ) - Don’t take ordinary stain. - More resistant to chemicals , dryness and heat. - Killed by autoclave. ENDOSPORE