MBIO

• Major Groups of Microorganisms

  • Prokaryotes
  • Eukaryotes
  • Acellular Microbes
• Prokaryotes


  Based on cell structure, no nucleus, Bacteria and Archaea
• Eukaryotes


  Have a nucleus, larger, more complex, Algae(photosynthetic), fungi, protozoa(animal-like)
• Acellular Microbes


  Non cellular, no nucleus, smaller than cells, Viruses (most scientists consider not living)
• Range in size


  • Very small: viruses ~ 20 nm
  • Very large: some protozoa ~ 5 mm
  • Best studied: Bacteria ~ micrometers
• 1m = 1000mm= 1000000 um = 1000000000 nm
• Why study Microbiology


  • Microbes are important members of the environment
  • Important members of the food chain
  • Breakdown and recycle organic wastes
  • Used by industry to produce: beer, wine, pickles, cheese, etc., pharmaceuticals including antibiotics, Genetically engineered to produce therapeutic substances: insulin (E.coli genetically modified)
  • Play a role in human immunity- Normal microbiota, or the microbiome
• Microbiome


  The entire collection of microorganisms that live in or on our body
• History of Microbiology


  • Robert Hooke
  • Antoni van Leeuwenhoek
  • Spontaneous Generation vs Biogenesis
  • Louis Pasteur
  • Joseph Lister
  • Robert Koch
  • Edward Jenner
  • Louis Pasteur
  • Paul Ehrlich
  • Alexander Fleming
• Spontaneous Generation


  Belief that some forms of life can arise from non-living matter
• Biogenesis


  Living matter arises only from pre-existing living matter
• Louis Pasteur


  • Used swan necked flasks to disprove the theory of spontaneous generation
  • Developed the principle of aseptic technique
  • Showed that microscopic yeast(single cell fungi) convert sugar to alcohol using a process called: fermentation
  • Heating the beer or wine after fermentation would kill the bacteria and prevent spoilage, this process is called pasteurization
  • His work on fermentation showed that microbes were responsible for chemical and physical changes to their environment, which prompted the speculation that microbes could also be responsible for disease
• Joseph Lister


  • Used phenol to clean surgical instruments and treat surgical wounds
  • Drastically reduced the incidence of surgical wound infections, led to the development of disinfectants and antiseptics
• Robert Koch


  • Investigated the cause of anthrax(disease of cows)
  • Isolated bacteria from the blood of infected cows, showed that a particular bacterium was present in all cases of the disease
  • Injected the bacterium into healthy cows, re-isolated bacteria from the injected cows and showed that they were identical to his first sample
  • Showed that a specific microbe was the cause of a particular disease, established a sequence of experimental steps that could be used to find the causative agent of other diseases-Koch's Postulates
• Edward Jenner


  • Developed a vaccine to protect against the disease smallpox
  • Observed that people who were previously sick with the mild disease cowpox did not get sick with small pox
  • Purposefully inoculated(immunizing against a disease) a young boy with cowpox, the boy became mildly ill and recovered along with being immune to smallpox
• Louis Pasteur


  • Bacterium that caused fowl cholera(contagious bacteria disease of birds) lost its ability to cause disease when grown in the lab for long periods of time, still able to induce immunity to fowl cholera when injected into healthy birds
  • Vaccination: A purposeful exposure to a killed or weakened microbe in order to induce an immune response
• Paul Ehrlich


  • Noticed that certain dyes stained bacteria differently than they stained animal cells
  • Proposed that a chemical might be found that would harm disease causing microbes without harming the host(selective toxicity)
  • Eventually discovered Salvarsan(an arsenic derivative that could be used to treat syphilis), beginning of chemotherapy
• Alexander Fleming


  • Noticed that mold inhibited bacterial growth on contaminated plates
  • Produced a natural compound called Penicillin(the first antibiotic)
  • Antibiotic: An antimicrobial chemical produced naturally by bacteria or fungi
• Nomenclature


  Naming system for microorganisms, genus(capitalized) and latinized, always written in italics or underlined
• Chemical Building Blocks and Chemical Bonds

  • Atom
  • Element
  • Molecule
  • Compound
• Atom


  The smallest chemical unit of matter
• Element


  Matter composed of one type of atom
• Molecule


  Two or more atoms combine to form
• Compound


  Two or more different types of atoms which form
• Structure of atoms


  • Every atom has a centrally located nucleus made up of protons (+) and Neutrons (neutral)
  • Nucleus is stable and does not participate in chemical reactions
  • Electrons circle the nucleus and are negatively charged, stabilize the positive charge of the nucleus
• Electrons


  Circle the nucleus and are negatively charged
• Chemical Bonds


  Form between atoms through interactions of electrons in their outer shells, the goal of every atom is to become chemically stable by filling its outermost shell with electrons
• Shells of electrons


  • 1st = 2 e-
  • 2nd = 8 e-
  • 3rd = 8 e-
• Ions


  Atoms (or group of atoms) that have a positive or negative charge
• Cation


  Positive ion, loss of an electron
• Anion


  Negative ion, gained an electron
• Types of chemical bonds found in living organisms

  • Ionic Bonds
  • Covalent Bonds
  • Hydrogen Bonds
• Ionic Bonds


  Result from attraction between ions of opposite charges
• Covalent Bonds


  Form when atoms share pairs of electrons, found in many compounds especially those that contain carbon
• Hydrogen Bonds


  Occur between covalently bonded molecules that display polarity, creates a region with partial negative charge (O) and a region with partial positive charge (H), loose attraction between oppositely charged regions of different molecules, weaker than ionic and covalent bonds
• Water as the Solvent of Life

  • Approx. 75% of cell weight is water
  • Water has an unequal charge distribution(which allows for hydrogen bonding), each water molecule can form up to 4 hydrogen bonds with other water molecules
  • Imparts a high boiling point (100 degrees Celsius), makes water resist rapid changes in temperature
  • Water is a polar solvent (likes to dissolve other polar and ionic compounds), unequal charge distribution allows it to dissolve many ionic compounds, positive region of water molecules surround negative ions, negative regions surround positive ions, holds the ions in solution
  • Water's polarity facilitates the splitting and joining of hydrogen ions (H+) and hydroxide ions (OH-), makes these ions available for chemical reactions
  • pH scale describes the concentration of H+ ions in a solution, pH 7 = neutral, pH below 7 = acidic, pH above 7 basic or alkaline
• Organic Molecules


  Any molecules that contain both carbon and hydrogen
• Four major classes of organic molecules

  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic Acids
• Carbohydrates


  Large group of compounds including sugars and starches, all contain the elements C, H and O often in the ration 1:2:1, generally polar(so they dissolve in water), ready source of energy for cells
• Types of Carbohydrates


  • Monosaccharides
  • Disaccharides
  • Polysaccharides