Micro3cellstructureandtaxonomy

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Micro3cellstructureandtaxonomy

  1. 1. CELL STRUCTURE AND TAXONOMY<br />
  2. 2. Cell is defined as the fundamental living<br /> unit of any organism.<br />Metabolism refers to all of the chemical reactions that occur within a cell.<br />Deoxyribonucleic acid (DNA) is the genetic material that makes up the genes of the cell’s<br /> chromosomes.<br />
  3. 3. Procaryotes are microorganisms that do not have the complex system of membranes and organelles.<br />Procaryotes include archaea, bacteria, and cyanobacteria.<br />
  4. 4. Eucaryotes are organisms that have a true nucleus and many membrane-bound organelles.<br />Eucaryotes include algae, protozoa, fungi, plants, animals, and humans.<br />
  5. 5. Acellular microorganisms (not composed of cells) include viroids, prions, and viruses.<br />
  6. 6. EUCARYOTIC CELL STRUCTURE<br />1. Cell Membrane<br />- encloses the cell<br />- selectively permeable<br /> 2. Nucleus<br /> - controls the functions of the entire cell<br /> and is called the “command center”<br /> - nucleoplasmis the gelatinous matrix<br /> where the chromosomes are suspended<br />
  7. 7. - the nuclear membrane encloses the <br /> nucleus<br /> - chromosomes consist of linear DNA<br /> molecules and proteins<br /> - genes are located along the DNA<br /> molecules<br /> - each gene contains the genetic <br /> information that enables the cell to<br /> produce a gene product<br />
  8. 8. - the organism’s complete collection of <br /> genes is its genotype (genome)<br /> - the nucleolus is the dark area in the <br /> nucleus where ribosomal ribonucleic acid<br />(rRNA) is manufactured<br />
  9. 9. 3. Cytoplasm<br /> - semifluid, gelatinous, nutrient matrix <br /> where storage granules and organelles <br /> are suspended, including endoplasmic<br /> reticulum, ribosomes, Golgi complexes,<br /> mitochondria, centrioles, microtubules,<br />lysosomes, and other membrane-bound<br /> vacuoles<br />
  10. 10. 4. Endoplasmic Reticulum (ER)<br /> - system of membranes that are <br /> interconnected and arranged to form a <br /> transport network of tubules and <br /> flattened sacs<br /> - rough endoplasmic reticulum (RER) has<br />many ribosomes attached to its outer<br />surface<br /> - smooth endoplasmic reticulum (SER) has<br />no attached ribosomes<br />
  11. 11. 5. Ribosomes<br /> - sites of protein synthesis<br /> 6. Golgi Complex<br /> - flattened, membranous sacs that <br /> communicates with the ER and completes <br /> the transformation of newly synthesized<br /> proteins into mature, functional ones and<br /> packages them into small vesicles for<br /> storage within the cell or export outside the<br /> cell<br />
  12. 12. - Golgi complexes are referred to as<br /> “packaging plants”<br /> 7. Lysosomes<br /> - vesicles that contain lysozyme and other<br /> digestive enzymes that break down <br /> foreign material taken into the cell by<br />phagocytosis<br />
  13. 13. - these enzymes also aid in breaking down<br /> worn out parts of the cell and may <br /> destroy the entire cell by a process <br /> called autolysis if the cell is damaged<br /> 8. Peroxisomes<br /> - vesicles that contain catalase which<br /> catalyzes the breakdown of hydrogen<br /> peroxide into water and oxygen<br />
  14. 14. 9. Mitochondria<br /> - sites of adenosine triphosphate (ATP)<br /> formation and are referred to as<br /> “powerhouses” of the cell<br /> 10. Plastids<br /> - sites of photosynthesis<br /> - a plastid called chloroplast contains a<br /> green, photosynthetic pigment called<br />chlorophyll<br />
  15. 15. 11. Cytoskeleton<br /> - include microtubules, microfilaments,<br /> and intermediate filaments<br /> - strengthen, support, and stiffen the cell,<br /> and give the cell its shape<br />
  16. 16. 12. Cell Wall<br /> - external structure that provides rigidity,<br /> shape, and protection to the cell<br /> - the cell walls of algae and plants contain<br />cellulose <br />- the cell walls of fungi contain chitin<br />
  17. 17. 13. Flagella<br /> - long, thin structures that are organelles<br /> of locomotion<br /> 14. Cilia<br /> - short, thin, numerous organelles of<br /> locomotion<br />
  18. 18. PROCARYOTIC CELL STRUCTURE<br />1. Cell Membrane<br /> - encloses the cell<br /> - selectively permeable<br />2. Chromosome<br />- single, long, supercoiled, circular DNA <br />molecule that is suspended in the <br />cytoplasm<br />
  19. 19. - a procaryotic cell contains neither<br />nucleoplasm nor a nuclear membrane<br /> - small, circular molecules of double-<br /> stranded DNA that are not part of the<br /> chromosome (referred to as plasmids)<br /> may also be present in the cytoplasm<br />
  20. 20. 3. Cytoplasm<br /> - semiliquid matrix<br /> 4. Cytoplasmic Particles<br /> - most of these are ribosomes<br /> - occur also in the form of cytoplasmic<br /> granules<br />
  21. 21. 5. Bacterial Cell Wall<br /> - the main constituent is a polysaccharide<br /> called peptidoglycan (murein)<br /> - provides rigidity, strength, and protection<br />
  22. 22. 6. Glycocalyx<br /> - slimy, gelatinous material produced by <br /> the cell membrane and secreted outside<br /> of the cell wall<br /> - Two types:<br /> 1. Slime layer<br /> - not highly organized and not firmly<br /> attached to the cell wall<br />
  23. 23. - enables certain bacteria to glide or<br /> slide along solid surfaces<br /> 2. Capsule<br /> - highly organized and firmly attached<br /> to the cell wall<br /> - serves an antiphagocytic function,<br /> protecting the encapsulated bacteria<br /> from being ingested by phagocytic<br /> white blood cells<br />
  24. 24. - S-colonies are smooth, mucoid, and<br /> glistening colonies on nutrient agar<br /> produced by encapsulated bacteria<br /> - R-colonies are dry, rough colonies<br /> produced by nonencapsulated<br /> bacteria<br />
  25. 25. 7. Flagella<br /> - threadlike, protein appendages for<br /> locomotion<br /> - Types of bacteria based on their flagella:<br /> 1. Peritrichous bacteria<br /> - bacteria possessing flagella over <br /> their entire surface<br /> 2. Lophotrichous bacteria<br /> - bacteria with a tuft of flagella at one<br /> end<br />
  26. 26. 3. Amphitrichous bacteria<br /> - bacteria that have one or more <br /> flagella at each end<br /> 4. Monotrichous flagella<br /> - bacteria possessing a single polar<br /> flagellum<br />
  27. 27. 8. Pili (Fimbriae)<br /> - hairlike structures composed of protein<br /> molecules called pilin that arise from the<br /> cytoplasm<br /> - Two types of pili:<br /> 1. A type that enables bacteria to adhere<br /> to surfaces<br /> 2. A sex pilusthat enables transfer of<br /> genetic material from one bacterial cell<br /> to another by conjugation<br />
  28. 28. 9. Spores (Endospores)<br /> - thick-walled structures that are a means<br /> of survival when their moisture or<br /> nutrient supply is low<br /> - the process of spore formation is called<br />sporulation, whereby a copy of the <br />chromosome becomes enclosed in thick<br />protein coats<br />
  29. 29. - spores are resistant to heat, cold, drying,<br /> and most chemicals<br /> - when the dried spore lands on a moist,<br /> nutrient-rich surface, it germinates, and<br /> a new vegetative bacterial cell emerges<br />
  30. 30. PROCARYOTIC CELL REPRODUCTION<br />Procaryotic cells reproduce by binary fission, in which one cell (the parent cell) splits in half to become two daughter cells.<br />Generation time is the time it takes for binary fission to occur.<br />
  31. 31. TAXONOMY<br />Taxonomy is the science of classification of living organisms.<br />Taxonomy consists of three separate but interrelated areas:<br /> 1. Classification<br /> - arrangement of organisms into <br /> taxonomic groups (taxa) on the basis of<br /> similarities or relationships<br />
  32. 32. - taxa include kingdoms or domains, <br /> divisions or phyla, classes, orders, <br /> families, genera, and species<br /> 2. Nomenclature<br /> - assignment of names to the various taxa<br /> according to international rules<br />
  33. 33. 3. Identification<br /> - process of determining whether an <br /> isolate belongs to one of the established,<br /> named taxa or represents a previously<br /> unidentified species<br />
  34. 34. MICROBIAL CLASSIFICATION<br />The science of taxonomy is based on the<br /> binomial system of nomenclature developed<br /> in the 18th century by the Swedish scientist<br />Carolus Linnaeus.<br />
  35. 35. In the binomial system, each organism is<br /> given two names.<br />The first name is the genus, and the second<br /> name is the specific epithet.<br />The first and second names together are<br /> referred to as the species.<br />
  36. 36. To express the genus, capitalize the first letter of the word and underline or italicize the whole word – for example, Escherichia.<br />To express the species, capitalize the first letter of the genus name (the specific epithet is not capitalized) and then underline or italicize the entire species name – for example, Escherichia coli.<br />
  37. 37. Frequently, the genus is designated by a single letter abbreviation; for example, E. coli<br /> indicates the species.<br />In an article about Escherichia coli, Escherichia would be spelled out the first time the organism is mentioned; thereafter, the abbreviated form, E. coli, could be used.<br />
  38. 38. The abbreviation “sp.” is used to designate a single species, whereas the abbreviation “spp.” is used to designate more than one species.<br />
  39. 39. Five-Kingdom System of Classification<br /> by Robert H. Whittaker<br /> 1. Bacteria and archaeans are in the<br /> Kingdom Procaryotae (or Monera)<br /> 2. Algae and protozoa are in the <br /> Kingdom Protista (organisms in this <br /> kingdom are referred to as protists)<br /> 3. Fungi are in the Kingdom Fungi<br /> 4. Plants are in the Kingdom Plantae<br /> 5. Animals Are in the Kingdom Animalia<br />
  40. 40. Three-Domain System of Classification<br /> by Carl R. Woese<br /> 1. Domain Archaea<br /> 2. Domain Bacteria<br /> 3. Domain Eucarya<br />

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