BIOL 1020 Unit I Module 1 Chapter 1.pdf - Chapter 1 Humans and the Microbial World 1 BIG PICTURE Discovery of the microbes Biogenesis versus spontaneous

BIOL 1020 Unit I Module 1 Chapter 1.pdf - Chapter 1 Humans...

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Unformatted text preview: 7/8/13 Chapter 1 Humans and the Microbial World 1 BIG PICTURE: Discovery of the microbes Biogenesis versus spontaneous generation Origins of microbiology Who is a microbe? Naming and distinguishing the microbes Food for thought A Glimpse of History English mathmatician •  Robert Hooke –  Described ‘microscopical mushroom’ (common bread mold) in 1665 –  “Cells” in cork 1 7/8/13 A Glimpse of History •  Science of microbiology born in 1674 •  Antony van Leeuwenhoek (1632–1723) –  Drapery merchant –  Made simple magnifying glass –  Studied lake water –  Observed ‘animalcules’! Importance of Microorganisms •  Microorganisms are foundaSon for all life on earth •  Have existed for ~3.5 billion years •  Plants, animals, modern microorganisms all evolved from ancestral bacteria •  Our life depends on their acSviSes first person to see bacteria observed in rainwater and own feces and scraped plaque from teeth before humans people believed that thigns came from nonliving ideas = spontaneous generation. humans noticed that when things are there for some time, it goes bad, and when examined has worms and bacteria The Dispute Over Spontaneous GeneraSon •  Theory of Spontaneous GeneraSon –  “Life arises spontaneously from non-­‐living material” –  This idea was difficult to dislodge –  Theory had supporters and detractors •  Detractors included –  Francesco Redi –  Louis Pasteur –  John Tyndall •  Each contributed to disproving the theory 2 7/8/13 showed that maggots were the offspring of The Dispute Over Spontaneous GeneraSon •  Italian biologist and physician Francesco Redi •  Demonstrated worms on ro`ng meat came from eggs of flies landing on meat (1668) –  Placed meat in two jars –  Covered one jar with gauze –  Gauze prevented flies from deposiSng eggs –  No eggs à no worms flies and flies did not arise did not come directly from meat only 200 years later would spontaneous generation be disproven further The Dispute Over Spontaneous GeneraSon believed that boiling would kill all living things. even with sealed vessels •  In 1749, John Needham demonstrated boiled broths sSll produced microorganisms •  In 1776, Father Spallanzani contradicted Needham’s results the broth would cloud which helped with the argument of spontaneous generation. –  Boiled broths longer; sealed flasks by melSng necks –  Broths remained sterile unless neck cracked •  Controversy remained –  Did heaSng destroy “vital force” necessary for spontaneous generaSon? The Dispute Over Spontaneous GeneraSon father of modern microbiology •  French chemist Louis Pasteur 3 7/8/13 The Dispute Over Spontaneous GeneraSon •  Developed swan-­‐necked flask –  Boiled infusions remained sterile despite opening to air –  Ended arguments that unheated air or broths contained “vital force” necessary for spontaneous generaSon contiminating organisms in air, boiling allowed for sterilization if protected from contamination, then it would putrify. flasks were freely open in the air, except the curve allowed to block the dust.. as long as the flask was upright and intact The Dispute Over Spontaneous GeneraSon •  English physicist John Tyndall finally explained conflicSng data –  Proved Pasteur correct –  Sterilizing broths required different Smes •  Some sterilized in 5 minutes •  Others not despite 5 hours of treatment –  Realized hay infusions contained heat-­‐resistant microbes •  Contaminated labs using hay Development of Medical Microbiology: Koch’s Postulates The Golden Age of Microbiology (1875–1918) –  Most pathogenic bacteria idenSfied –  Robert Koch pasteur found endospores = head resistant forms of bacteria john tyndall= tyndalization, biogenesis, life can only arise from preexisting life bacertia associated with human disease was studied and there was an understanding that they affect humans. ABX and vaccines were developed Koch created medical microbio 4 7/8/13 found that this was always present in blood Development of Medical Microbiology: Koch’s Postulates •  Robert Koch (1875)-­‐ physician studying bacterium Bacillus anthracis (Anthrax) Isolated B. anthracis from infected ox Grew it in the lab cultured bacteria could cause disease in a new animal. Used the pure culture to infect laboratory mice Mice became sick Koch recovered B. anthracis from the infected mice formed the standards by which diseases Development of Medical Microbiology: Koch’s Postulates •  Robert Koch (1875)-­‐ physician studying bacterium Bacillus anthracis have been studied. Koch's postulates •  Koch’s Postulates – Criteria used to establish that a specific microorganism causes a specific disease 1. Microbe present in every case of the disease 2. Isolated from diseased host and grown in pure culture 3. Disease reproduced when microbe is put back into healthy host 4. Same microbe recovered from experimentally-­‐infected host Medical Microbiology •  Most microorganisms are not harmful •  Some are pathogens –  Cause disease –  Influenza in 1918–1919 killed more Americans than died in WWI, WWII, Korean, Vietnam, and Iraq wars combined •  Modern sanitaSon, vaccinaSon, and effecSve anSmicrobial treatments have reduced incidences of the worst diseases 5 7/8/13 Past Triumphs •  Viral disease smallpox once a leading killer –  ~10 million deaths over 4,000 years –  Devastating on unexposed populations (e.g., Aztecs in New World) –  Worldwide eradication attempts eliminated disease •  No reported cases since 1977 •  Plague another major killer in history –  ~1/3 of population of Europe (or ~25 million individuals) died between 1346–1350 –  Today, fewer than 100 die worldwide •  Polio •  Leprosy Present and Future Challenges •  Despite impressive progress in health, much work remains –  Especially true for viral diseases and diseases associated with poverty –  Respiratory infecSons, diarrheal diseases cause most illness and deaths in world today •  In United States, ~750 million infecSons per year –  ~200,000 deaths –  Cost in tens of billions of dollars Present and Future Challenges •  New diseases arise conSnuously rapid changes and dramatic diseases that suddenly become prevalent are called emerging diseases 6 7/8/13 Present and Future Challenges •  Emerging diseases –  Most newly recognized –  MulSple examples •  Swine flu •  Middle East Respiratory Syndrome Coronavirus (MERSCoV) •  MulSdrug-­‐resistant tuberculosis •  Lyme disease •  HepaSSs C •  Acquired immunodeficiency syndrome •  HemolySc uremic syndrome •  Hantavirus pulmonary syndrome •  Mad cow disease •  West Nile encephaliSs Present and Future Challenges climate change •  Emerging diseases –  Pathogens can become resistant to anSmicrobial medicaSons (e.g., tuberculosis, malaria) –  Increased travel and immigraSon •  Many diseases eliminated from developed countries sSll exist in many parts of world (e.g., malaria, cholera, plague, yellow fever) –  Changes in populaSon •  Weakened immune systems (e.g., elderly, HIV/AIDS) –  Chronic diseases may be caused by bacteria •  E.g., pepSc ulcers caused by Helicobacter pylori •  Possibly indigesSon, Crohn’s disease, and back pain, for example Present and Future Challenges •  Re-­‐emerging diseases –  VaccinaSon can become vicSm of own success –  Lack of firsthand knowledge of dangers of diseases can lead people to fear vaccines more than the diseases •  Diseases such as measles, mumps, whooping cough nearly eradicated from U.S. but could re-­‐emerge with declining vaccinaSon rates in britain, parents are failing to immunize because of measles. Wales, Nov 2012, 12,000 cases. 2011 only had 19 cases total. 7 7/8/13 Host-Microbe Interactions •  Not all microbes cause disease all the Sme •  All surfaces of human body populated by microorganisms •  Beneficial microbes –  Termed normal microbiota or normal flora –  Prevent diseases by compeSng with pathogens –  Development of immune system response –  Aid in digesSon more people killed in disease than in war normal microbiota - contribute to wellness but can enter sterile or inappropriate parts and can cause hurt •  The beneficial microbes can become pathogens –  Damage body Sssues à disease symptoms The Living World of Microbes •  Enormous numbers –  Bacterial species outnumber mammalian species by factor of 10,000 –  ConsideraSons of biodiversity typically overlook enormous contribuSon of microbes –  Less than 1% of all microbial species can be grown and studied in laboratory microbes are found in every observable habitat on earth. Microbiology: A Human PerspecSve •  We could not survive on earth without microorganisms •  Numerous benefits §  Examples include nitrogen fixaSon, oxygen producSon, degradaSon of materials (e.g., cellulose, also sewage and wastewater) 8 7/8/13 Applications of Microbiology •  BiodegradaSon –  Degrade PCBs, DDT, trichloroethylene and others –  Help clean up oil spills –  BioremediaSon: using microorganisms to hasten decay of pollutants •  Bacteria synthesize commercially valuable products •  Examples include: –  –  –  –  –  –  –  –  Cellulose (stereo headsets) Hydroxybutyric acid (manufacture of disposable diapers and plasScs) Ethanol (biofuel) Hydrogen gas (possible biofuel) Oil (possible biofuel) Insect toxins (insecScides) AnSbioScs (treatment of disease) Amino acids (dietary supplements) Applications of Microbiology •  Biotechnology –  Use of microbiological and biochemical techniques to solve pracScal problems •  GeneSc engineering –  IntroducSon of genes into another organism –  Disease-­‐resistant plants –  ProducSon of medicaSons (e.g., insulin for diabetes) Taxonomy of Microorganisms •  All living things can be classified into one of three groups, or domains –  Bacteria –  Archaea –  Eucarya •  Organisms in each domain share certain important properSes 9 7/8/13 Taxonomy of Microorganisms Taxonomic Categories (taxa) •  Taxonomy – Science of classifying living beings •  ClassificaAon – Arranging organisms into taxonomic categories •  Nomenclature – Assigning scienSfic names to organisms based on their taxa normanclature, charles linneus •  Binomial system of assigning scienAfic names Domain Bacteria •  Bacteria –  Single-­‐celled prokaryotes –  No membrane-­‐bound nucleus –  No other membrane-­‐bound organelles –  DNA in nucleoid –  Most have specific shapes (rod, spherical, spiral) –  Rigid cell wall contains pepSdoglycan (unique to bacteria) –  MulSply via binary fission –  Many move using flagella Domain Archaea •  Archaea –  Like Bacteria, Archaea are prokaryoSc –  Similar shapes, sizes, and appearances to Bacteria –  MulSply via binary fission –  May move via flagella –  Rigid cell walls no membrane bound nucleus •  However, major differences in chemical composiSon –  Cell walls lack pepSdoglycan –  Ribosomal RNA sequences different •  Many are extremophiles –  High salt concentraSon, temperature less closely related to bacteria but is more relate to eucarya 10 7/8/13 Domain Eucarya •  Eucarya –  Eukaryotes = “true nucleus” –  Membrane-­‐bound nucleus and other organelles –  More complex than prokaryotes –  Microbial members include fungi, algae, protozoa •  Algae and protozoa also termed proSsts •  Some mulScellular parasites including helminths (roundworms, tapeworms) considered as well Domain Eucarya •  Algae –  Diverse group –  Single-­‐celled or mulScellular –  PhotosyntheSc •  Contain chloroplasts with chlorophyll or other pigments –  Primarily live in water –  Rigid cell walls –  Many have flagella do not have connective tissue between cells as do plants •  Cell walls, flagella disSnct from those of prokaryotes •  Fungi Domain Eucarya –  Diverse group –  Single-­‐celled (e.g., yeasts) or mulScellular (e.g., molds, mushrooms) –  Energy from degradaSon of organic materials –  Primarily live on land lack photosynthetic pigments recycling organic matter 100.000 fungal species have been described with 1.5 million reported to exist. most closely to related to animals 11 7/8/13 Domain Eucarya nonphototrophic •  Protozoa –  Diverse group –  Single-­‐celled –  Complex, larger than prokaryotes –  Most ingest organic compounds –  No rigid cell wall –  Most moSle Nomenclature •  Binomial System of Nomenclature: two words –  Genus (capitalized) –  Specific epithet, or species name (not capitalized) –  Genus and species always italicized or underlined –  E.g., Escherichia coli –  May be abbreviated (e.g., E. coli) Non-­‐Living Members of the Microbial World •  •  •  •  Viruses, viroids, prions Acellular infecSous agents Not alive Not microorganisms, so general term microbe ouen used to include 12 7/8/13 Non-­‐Living Members of the Microbial World •  Viruses smaller than cells either DNA or RNA for genetic material –  Nucleic acid packaged in protein coat –  Variety of shapes –  Infect living cells, termed hosts surrounded by protein shell or capsid o MulSply using host machinery, nutrients o InacSve outside of hosts: obligate intracellular parasites –  All forms of life can be infected by different types require cells to replicate Non-­‐Living Members of the Microbial World •  Viroids lack a protein capsid they still have a extracellular form that –  Simpler than viruses –  Require host cell for replicaSon –  Consist of single short piece of RNA –  No protecSve protein coat –  Cause plant diseases –  Some scienSsts speculate they may cause diseases in humans PSTV T7 DNA •  No evidence yet allows them to move from one host cell to another do not affect bacteria and animal cells PSTV 1 um Non-­‐Living Members of the Microbial World •  Prions highly infectious fatal neurologic diseases –  InfecSous proteins: misfolded versions of normal cellular proteins found in brain –  Misfolded version forces normal version to misfold •  Abnormal proteins bind to form fibrils •  Cells unable to funcSon –  Cause several neurodegeneraSve diseases in humans, animals –  Resistant to standard sterilizaSon procedures 13 7/8/13 Members of the Microbial World Microbial World Infectious agents (non-living) Organisms (living) Domain Bacteria Archaea Viruses Eucarya Viroids Prions Eukaryotes Prokaryotes (unicellular) Algae (unicellular or multicellular) Protozoa (unicellular) Fungi (unicellular or multicellular) Helminths (multicellular parasites) Protists Size in the Microbial World Size in the Microbial World •  Enormous range –  Largest eukaryoSc cells ~a million Smes larger than smallest viruses •  Wide variaSons even within a group –  Bacterium ~600 µm x 80 µm discovered in mid 1990s •  Visible to naked eye –  Bacterium 70 Smes larger in volume discovered in 1999 –  EukaryoSc cell ~1 µm found •  Similar in size to typical bacteria 14 7/8/13 Size in the Microbial World •  Extremes of size –  Enormous prokaryote; Sny eukaryote –  Smallest prokaryote ~400 nm, contains ~1/10th as much DNA as E. coli •  Internal structures –  ProkaryoSc Planctomyces have membrane surrounding nucleoid; carry out endocytosis Epulopiscium (prokaryote) Paramecium (eukaryote) 0.1mm Second Golden Age of Microbiology •  Less than 1% of prokaryotes ever studied •  Most do not grow in lab •  New sequencing approaches revealing enormous biodiversity of microbial world –  E.g., 1,800 new bacterial species found in Sargasso Sea •  Major challenges remain •  Exploring microbial world should answer many fundamental biological quesSons Create a summary of the microbes •  Draw a Venn diagram with the following sets: ¤  Prokaryotes ¤  Eukaryotes ¤  Protists ¤  Multicellular organisms ¤  Single cell organisms ¤  Viruses ¤  Viroids ¤  Prions 15 7/8/13 Food for thought •  How would you persuade a friend that microbes are more than just agents of disease? •  Where are the Bacteria located in your Venn diagram? Fungi? Helminths? •  Why is there no overlap between Prions, Viroids, Viruses, and the rest of the diagram? 16 ...
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