MICROPARA - MODULE 2 AND 3

• Bacteria are very small to be seen by our naked eye.
• Types of Microorganism


  • Cellular Microorganism
  • Acellular Microorganism

  
• Cellular Microorganism


  Organism that contain cells, either unicellular or multicellular

  
• Cellular Microorganism - Unicellular

  • Prokaryotes (Archaea, Bacteria, Cyanobacteria)

  
• Cellular Microorganism - Unicellular/Multicellular

  • Eukaryotes (Algae, Fungi, Protozoa)

  
• Acellular Microorganism


  Organism that doesn't contain cell

  
• Acellular Microorganism


  • virus, viroids, prions
• Prokaryotic Cell


  • No true nucleus
  • Ave size: 0.2 – 2.0 μm (diameter), 2 – 8 μm (length)
  • Lack membrane-enclosed organelles
  • No cytoskeleton
  • Transverse binary fission
  • Monomorphic or pleomorphic
• Archaea


  • Archaea means ancient
  • Archaea bacteria look identical microscopically to members of the Bacteria domain
  • Chemical composition of cell wall differs: Archaea do not have peptidoglycan
  • Have the ability to grow in extreme environments
• Bacteria


  • Single-celled prokaryote
  • Prokaryote is a simple cell with a nucleoid region, surrounded by cytoplasm and a cell wall

  
• Bacterial Shapes


  • Bacilli - rod shaped
  • Cocci - spherical shaped
  • Spirilla - spiral shaped

  
• Bacterial Multiplication


  Binary fission - one cell divides into two cells, identical to original
• Prokaryotic Cell Structure - Appendages

  • Glycocalyx
  • Flagella
  • Fimbriae
  • Pili
  • Axial filaments

  
• Glycocalyx


  • The outer layer usually made up of bound polysaccharides on the cell surface and superficial layer of unbound proteoglycans and glycoproteins
  • Capsule
  • Anti-phagocytic function
  • Vaccine target
  • Attachment
  • Slime layer
  • Glide or slide on surfaces
  • Formation of biofilm

  
• Flagella


  • Long, slender, threadlike, whip-like extension of certain cells or unicellular organisms used mainly for movements
  • Arrangements: Atrichous, Monotrichous, Lophotrichous, Amphitrichous, Peritrichous
• Fimbriae


  Hair-like structures made of "pilin" that enable bacterial cell to adhere to surfaces

  
• Pili


  • Short, filamentous projection on a bacterial cell, used not for motility but for adhering to other bacterial cell (especially for mating) or to animal cells
  • Joins bacterial cell for DNA transfer during conjugation

  
• Axial filaments


  Flagella-like fibrils arising at the ends
• Prokaryote: Cell Wall


  • Composed of peptidoglycan (murein)
  • N-acetylglucosamine (NAG)
  • N-acetylmuramic acid (NAM)
  • Used to characterized bacterial cells

  
• Differences between Gram Positive and Gram Negative Organisms

  • Staining
  • Cell wall
  • Lipid content
  • Periplasmic space
  • Flagella
  • Spores
  • Pili

  
• Gram Positive


  • Cell wall contains teichoic acid
  • Outer membrane absent
  • Peptidoglycan thicker
  • Low lipid content
  • Periplasmic space absent
  • Flagella have two rings in basal body
  • Mostly spore-forming
  • Pili over cell surface absent

  
• Gram Negative


  • Teichoic acid absent in cell wall
  • Outer membrane present
  • Peptidoglycan thinner
  • High lipid content
  • Periplasmic space present
  • Flagella have four rings in basal body
  • Generally non-sporous
  • Some have pili over cell wall
• Internal to Cell Wall

  • Plasmid
  • Ribosomes
  • Inclusions
  • Endospore
• Plasmid


  Contains extra-chromosomal DNA which carry genes that confer protective trait that may be duplicated and passed on to an offspring
• Ribosomes


  Minute particle composed of protein and ribonucleic acid (RNA) that serves as the site of protein synthesis
• Inclusions


  An abnormal structure in a cell nucleus or cytoplasm having characteristic staining properties
• Endospore


  Bacteria undergo sporulation during exposure to harsh conditions
• Comparison of Three Cellular Domains

  • Bacteria
  • Archaea
  • Eukarya

  
• Bacteria


  • Prokaryotic cell type
  • Single, circular chromosome
  • 70S ribosomes
  • Peptidoglycan in cell wall
  • Fatty acids with ester linkages in cell membrane

  
• Archaea


  • Prokaryotic cell type
  • Single, circular chromosome
  • 70S ribosomes but structure more similar to 80S
  • No peptidoglycan in cell wall
  • Long chain, branched hydrocarbons with ester linkages in cell membrane

  
• Eukarya


  • Eukaryotic cell type
  • Several, linear chromosomes
  • 80S ribosomes
  • No peptidoglycan in cell wall
  • Fatty acids with ester linkages in cell membrane
  • Sterols in membrane
• Eukaryotic Cell


  • All members of the living world except the prokaryotes
  • Single celled and multi-celled
  • Contain basic organelles: cell membrane, cytoplasm, nucleus
  • Membrane bound "true" nucleus
  • Ave size: 10 – 30 μm
  • Mitosis/meiosis

  
• Eukaryotes


  • Algae
  • Fungi
  • Protozoa

  
• Algae


  • Photosynthetic eukaryotes with a wide variety of shapes that occur in most habitats
  • Small, single-celled forms to complex multicellular forms
  • Not plants, more plantlike than protozoa
  • Lack true roots, stems and leaves

  
• Fungi


  • Can be single celled or very complex multicellular organisms
  • Found in just about any habitat but most live on the land, mainly in soil or on plant material
  • Decomposers that play an important role in the cycling of carbon and other elements
• Protozoa


  • Single celled organisms that come in many different shapes and sizes
  • Live in a wide variety of moist habitats including fresh water, marine environments and the soil
  • Some are parasitic, causing disease like malaria
  • Motile and can move by means of flagella, cilia, and amoeboid movement

  
• Cell Organelles and its Function

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Chloroplasts
  • Endoplasmic reticulum
  • Golgi apparatus
  • Central vacuole
• Virus


  • Considered acellular, non-living, obligate intracellular parasite
  • Made up of a core containing DNA or RNA surrounded by a protein coat
  • Can reproduce only by using the cellular mechanism of another cell
  • Often considered the parasites of the microbial world
• Viroids


  • Very small, circular RNA (may appear linear), and infectious in plants
  • Do not contain a capsid
• Prions


  • Contain only protein
  • Causative agent for some neurodegenerative diseases in humans and animals