* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download eprint_1_17645_235
Survey
Document related concepts
Signal transduction wikipedia , lookup
Cell nucleus wikipedia , lookup
Biochemical switches in the cell cycle wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell culture wikipedia , lookup
Cell membrane wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Cell growth wikipedia , lookup
Lipopolysaccharide wikipedia , lookup
Endomembrane system wikipedia , lookup
Transcript
Nursing college, Second stage Microbiology Dr.Nada Khazal K. Hendi Lecture-2- Eukaryotes & Prokaryotes The following table illustrates the main differences between Eukaryotic cells & Prokaryotic cells: Structure Definite Nucleus Nuclear membrane Chromosome Cell envelope Nucleolus Organelles.(mitocondria, Golgi apparatus, ribosome Replication Representative organisms Eukaryotic cells Yeas Yeas Multiple Yeas, have flexible cell mem. Except fungi have rigid cell wall with chitin Yeas Prokaryotic cells No No Single Yeas, have rigid cell wall that contain peptidoglycan No Yeas No Large 80 S ribosome By mitosis Small 70 S ribosome By binary fission Animals, plant, protozoa, fungi Bacteria The following table illustrates the comparison of medical important organism characteristic Cells Viruses No cell (particle) Bacteria Yeas Diameter(μm) 0.02-0.3 smallest MO 1-0.5 Nucleic acid Either DNA or RNA Nature of outer surface proteins Capsid and lipoprotein envelope ribosome absent Produce many copies of Nucleic acid and protein, then, reassemble into multiple progeny viruses. They are replicate only within living cell none Methods of Replication Motility 1 Both rigid cell wall that contain peptidoglycan 70 S Fungi Yeas 3-10 (yeast) Both rigid cell wall with chitin 80 S Protozoa Yeas 15-25 trophozoite Both Flexible cell mem. Except 80 S By binary fission Budding or mitosis mitosis some none most Nursing college, Second stage Microbiology Dr.Nada Khazal K. Hendi Scientific name: The binomial system of published by C. Linnaeus. The genus and species are significant taxonomic uses in binomial nomenclature for each organism. First name for genus and second name for species. First letter of genus should be written in capital letter, whereas first letter of species, must be write in small. Name of genus and species for any organism must be write in Italic from or place line under each genus and species. Ex: Staphylococcus aureus. Name of bacteria are derived from 1. The name of disease that caused by bacteria. Ex: Vibrio cholerae= causes cholerae. 2. The locality where the bacteria was first isolated. Ex: Escherichia coli=from colon. 3. The scientists responsible for isolating bacteria. Listeria= Lister. 4. Properties of bacterial morphology and physiology. Staphylococcus aureus= cluster. Classification of MO The importance of classification: 1. To establish the criteria for identification. 2. To arrange similar organisms in to groups. 3. To provide information about how organism evolved. 4. To avoid the confusing in the information about different types of organisms. All types of organisms classified in to five kingdom; monera, protista, fungi, plantae, and animalia. The following table illustrates the kingdom. Kingdom Types of cell Organism monera Prokaryotes Bacteria protista Eukaryotes Protozoa fungi Eukaryotes fungi plantae Eukaryotes plant animalia Eukaryotes Man, animals 2 Nursing college, Second stage Microbiology Dr.Nada Khazal K. Hendi Shapes and size of bacteria and patterns of arrangement 1. spherical (cocci); A: singular cocci. B: diplococci (pairs of cells). C: streptococci (chains). D:staphylococci (clusters or grape like).E: tetrad: four cocci 2. Bacilli (rod like); A: singular bacillus. B: diplobacilli (pairs of cells). C: streptobacilli (chains). D:coccobacilli ( spherical to rod) 3. spirochetes: spirilium (spiral). F vibrio (comma). 4. pleomorphic (appear in many shape). Bacterial size Most disease causing by bacteria range in size from 0.2 -5 μm in diameter and 0.4-14 μm in length approximately. The bacterial cells are about the size of mitochonderia. Structure and function of bacterial cell Cell wall The bacteria are surrounding by rigid cell wall. The principle structural component of cell wall is peptidoglycan. Peptidoglycan (PG) is complex of polysaccharide and polypeptide. Most bacteria are classified according to reaction of Gram stain with components of cell wall into major groups; Gram positive & Gram negative bacteria. The cell wall of Gram positive differs from Gram negative. Gram positive bacteria have thick cell wall and teichoic acid, while Gram negative bacteria have thin cell wall and no teichoic acid. The large amounts of PG make Gram positive bacteria susceptible to antibiotics (penicillin) that inhibit cell wall synthesis. All bacteria have cell wall except Mycoplasma. Function of cell wall: 1. Protection the internal structures. 2. Give shape the cell. 3. Contain component which toxic to host cell. Cell membrane (plasma membrane): Cell membrane is composed of two layers of lipid (the lipids linked to proteins and to polysacchrides). It is located under cell wall. 3 Nursing college, Second stage Microbiology Dr.Nada Khazal K. Hendi Gram negative bacteria have inner and, whereas Gram positive bacteria have only inner cell membrane. The space between inner and outer membrane called periplasmic space. Outer cell membrane of Gram negative bacteria is composed of lipopolsaccharide (LPS) and lipoproteins. LPS acts as endotoxine. Function of cell membrane 1. Control on inflow of metabolites to from cell by control on active transport of molecules into cell because it has selective permeability. 2. Energy generation by oxidative phosphorylation. 3. Secretion of enzyme and toxin. 4. Synthesis of precursors of cell wall (have important role in synthesis of cell wall). Nucleoid The bacterial genome consists of a single chromosome. It is not surrounded by nuclear membrane. Some bacteria have small, circular of DNA (plasmid) as free in cytoplasm. Ribosome It is composed of several RNA and proteins. The 70s unit is composed of two small subunits (50s and 30s), while eukaryotic ribosome is consist of 80s (60s and 40s). The important role of it: 1. The ribosomes are site of protein synthesis. 2. The differences in rRNA and protein constitute of bacteria, the basis of selective action of several antibiotics (tetracycline) that inhibit bacterial protein synthesis. External structures A – Capsule: some bacteria have capsule. It is a gelatinous layer covering the entire bacterium, may be composed polysaccharide or poly peptide. Capsule importance: 1. Protection against deleterious agents (Lytic enzyme). 2. Contribute to virulence of many bacteria (inhibiting phagocytosis) &it play role in adherence of bacteria to human tissues. 3. it is used as antigen (K- antigen)in certain vaccines. 4. specific identification of MO. 4 Nursing college, Second stage Microbiology Dr.Nada Khazal K. Hendi Flagella: It is long filamentous appendages. They are organ of locomotion The flagella may be located at one end or both ends of bacteria, in other they are over the outer surface. Most rod bacteria have flagella (motile), while most cocci are non motile. Function: 1. organ for motility. 2. may play role in pathogenesis. 3. act as antigen (H- antigen). Pili (Fimbriae) It is hair like filaments that extend from cell membrane. They are shorter and straighter than flagella. They are fond mainly in Gram negative bacteria. Pili have important role: 1. they mediate the attachment of bacteria to specific receptor on human cells. 2. have role in transfer of genetic material between bacteria through conjugation. 5