BIOL 203 – Final Exam Study Guide with Complete Solutions Graded A 2024

Antoni van Leeuwenhoek: contributions created quality microscopes, allowing him to see the previously unknown microbial world 6 groups of microorganisms bacteria, archaea, fungi, protozoa, algae, small multicellular animals Bacteria (domain, type, cell wall, reproduction, notable features) domain: bacteria type: unicellular cell wall: peptidoglycan (has sugar component) reproduction: asexual notable: most are not pathogenic Archaea (domain, type, cell wall, reproduction, notable features) domain: archaea type: unicellular cell wall: polysaccharide or protein reproduction: asexual notable: closer to eukaryotes than bacteria, can tolerate extreme environments Fungi (domain, type, cell wall, reproduction, notable features) domain: eukarya type: uni/multicellular cell wall: chitin or glucomannan (a sugar) reproduction: asexual/sexual notable: categorized as molds (multicellular filaments) or yeast (unicellular and round) Protozoa (domain, type, cell wall, reproduction, notable features) domain: eukarya type: unicellular cell wall: none reproduction: asexual/sexual notable: similar to animals, capable of locomotion Algae (domain, type, cell wall, reproduction, notable features) domain: eukarya type: uni/multicellular cell wall: cellulose (carb), proteins and agar reproduction: asexual/sexual notable: photosynthetic Parasitic worms (domain, type, cell wall, reproduction, notable features) domain: eukarya type: multicellular cell wall: none reproduction: usually sexual notable: not microscopic but lays microscopic eggs Virus (domain, type, cell wall, reproduction, notable features) domain: ??? type: acellular cell wall: N/A reproduction: obligate parasite → cannot reproduce on their own notable: not alive?? too small to see with light microscope Golden Age of Microbiology questions 1. Is spontaneous generation of microbial life possible? 2. What causes fermentation? 3. What causes disease? 4. How can we prevent infection and disease? Is spontaneous generation (abiogenesis) of microbial life possible? → Francesco Redi - placed meat into 3 flasks - decaying meat in unsealed flask was infested with maggots - decaying meat in sealed flask/flask covered with gauze did not get infested with maggots Is spontaneous generation (abiogenesis) of microbial life possible? → John Needham - boiled beef gravy with infusions of plant/animal material that contained microbes in vials sealed with corks - vials became cloudy and showed microscopic animals when examined Is spontaneous generation (abiogenesis) of microbial life possible? → Lazaro Spallazani - repeated Needham's experiments but boiled the infusions longer and sealed the vials completely by melting the neck - did not observe any growth Is spontaneous generation (abiogenesis) of microbial life possible? → Louis Pasteur - repeated Spallazani's experiments with S-shaped flasks that allowed air to enter - infusions remained sterile after boiling - growth was seen if the infusion came into contact with the dust from the air settled in the bend How did Pasteur refute that spontaneous fermentation occurs? - heated flask of grape juice to kill all microbes - sealed flask - found that no fermentation occurred and juice remained free of microbes How did Pasteur refute that air ferments grape juice? - heated flask of grape juice to kill all microbes - flask remained open to air via curved neck - found that no fermentation occurred and juice remained free of microbes How did Pasteur refute that bacteria ferment grape juice into alcohol? - heated flask of grape juice to kill all microbes - juice in flask was inoculated with bacteria and sealed - found that bacteria reproduce/acids are produced How did Pasteur conclude that yeasts ferment grape juice into alcohol? - heated flask of grape juice to kill all microbes - juice in flask was inoculated with yeast and sealed - found that yeasts reproduce/alcohol is produced Why is Pasteur the "father of microbiology" - discovered anaerobic bacteria (grow in absence of O2) fermented glucose into acids - discovered that yeast were facultative anaerobes (can grow with or without O2) - popularized pasteurization where wine was heated to kill microorganisms and yeast was added after - germ theory of disease Eduard Buchner: contributions - demonstrated that fermentation is performed by enzymes and does not require living cells - began the field of biochemistry and the study of metabolism Koch's postulates: Steps that must be taken to prove the cause of an infectious disease 1) the suspected causative agent must be found in every case of the disease and be absent from healthy hosts 2) the agent must be isolated and grown outside of the host 3) when the agent is introduced to a healthy host, the host should get the disease 4) the same agent must be found in the diseased experimental host Hans Christian Gram: contributions