Introduction to Microbiology
Module 1
1.1 The Science and History of Microbes
• What is microbiology?– Microbes are ubiquitous– Pathogens and Non-pathogens
• Why study microbiology?– Indigenous microflora & clinical importance– Food Production– Bioremediation– Biotechnology
Causes of Disease
• Infectious Disease: pathogen colonizes the body and subsequently causes disease
• Microbial Intoxication: person ingests a toxin that was produced by a microorganism
Subdivisions in Microbiology
• Prokaryotic– Bacteria– Archaea
• Eukaryotic– Algae– Fungi– Protozoa
• Acellular– Virus– Viroid– Prion
Pioneers of Microbiology
• 1674 Anton van Leeuwenhoek
• 1796 Edward Jenner
• 1847 Ignaz Semmelweis
• 1853 John Snow
• 1857, 1861, 1864, 1881, 1885 Louis Pasteur
• 1867 Joseph Lister
• 1876, 1881, 1884 Robert Koch
Pioneers of Microbiology
• 1884 Christian Gram
• 1904 Paul Ehrlich
• 1928 Frederick Griffith
• 1929 Alexander Fleming
• 1944 Avery, MacLeod, McCarthy
• 1948 Barbara McClintock
• 1953 Watson, Crick, Franklin, Wilkins
Earliest Known Infectious Diseases
• Tuberculosis, Israel 7000 B.C.
• Pestilence, Egypt 3180 B.C.
• Smallpox, China 1122 B.C.
• Plague, Rome 800-430 B.C. (4 outbreaks)
• Syphilis, Europe 1500 A.D.
Germ Theory
• Germ theory: microorganisms can cause disease
• Spontaneous generation: the idea that life can arise from non-living
• Biogenesis: life can only arise from living organisms
• Pure culture: a laboratory culture containing only a one single species of organism
Koch’s PostulatesPostulates
1 -Microbes must be present in diseased, not healthy organisms
2 -Isolate & grow organism in pure culture
3 -Inoculate healthy organism with pure culture, organism will develop the disease
4 -Recover same microbe from experimentally infected organism and grow again in pure culture
Exceptions1 -Some microbes will not grow
in vitro
2 -Obligate intracellular pathogens: can only survive and multiply within living host cells
3 -Some pathogens ONLY infect humans and therefore can not be inoculated into other animals for testing*cell culture models
4 – Some diseases are caused by synergistic infection
Microbiology Today
• Chemotherapy– Antibiotics– Synthetic drugs
• Immunology– Study of disease and
the body’s response to it
• Virology– Study of viruses and
viral diseases
• Basic Biology– Using microorganisms
to study metabolism and genetic properties similar to plants and animals
• Genetic Engineering– Genomics– Recombinant DNA
technology
Careers in Microbiology
• Microbiology Subdivisions– Bacteriologist (bacteria)– Phycologist (algae)– Protozoologist (protozoa)– Mycologist (fungi)– Virology
• Immunologist
• Biotechnologist
1.2 Molecules & Metabolism Review
• Macromolecules– Carbohydrates– Lipids– Protein– Nucleic Acid
• Atoms• Bonding• Polar and nonpolar
molecules• Chemical reactions• Solvents & Solutes• Acids & Bases, pH• Organic molecules
Basic Chemistry: Atoms
• Atoms: the smallest component of an element, having properties of that element– Nucleus
• Protons (+)• Neutrons (0, no charge)
– Outer shell• Electrons (-)
• Elements: matter composed of a single type of atom
Basic Chemistry: Bonding
• Chemical bonds form because of interaction of the electrons
• Covalent bonds– Atoms share pairs of electrons; strongest
• Ionic bonds– Atoms complete their outermost shell by gaining or
losing electrons and are then attracted to each other because of opposing charges
• Hydrogen bonds– Hydrogen atoms interact with two or more parts of
another molecule; weakest but vitally important for life
Covalent Bonds
• Polar Molecules– Covalent bond in
which shared electrons are not equally spaced
– Example: water
• Nonpolar Molecules– Covalent bond in
which shared electrons are equally spaced
– Example: ethane
Chemical Reactions
• Atoms or molecules making or breaking chemical bonds
• Energy is required– Endothermic- energy captured and used– Exothermic- energy produced and released
• Activation energy
• Rate of reaction
Solvents and Solutes
• Solution: molecules dispersed in liquid
• Solute: molecules that are dispersed
• Solvent: liquid component of solution
• Example: NaCl (table salt) dissolving in water.– NaCl is the solute– Water is the solvent
Acids, Bases, and pH
• Pure water= neutral, equal H+ and OH-
• Acids: contain more H+ than OH-
• Bases: contain more OH- than H+
• pH is based on the concentration of H+– Range 0 to 14
• 0 is the most acidic• 7 is neutral• 14 most basic (alkaline)
Organic Molecules
• Contain carbon (C) and hydrogen• Carbon can form 4 bonds which makes it
very versatile• Complex structures
– Linear– Branched– Rings
• Basis of the macromolecules– Carbohydrates, lipids, protein, nucleic acid
Carbohydrates
• Carbon and water (CH2O)– Monosaccharides (single sugars, monomers)
• Glucose, fructose, ribose, deoxyribose• Glucose is the building block for many polysaccharides
– Disaccharides (two sugars)• Sucrose, lactose
– Polysaccharides (many sugars, polymers)• Glycogen, cellulose, amylose
• Functions:– Energy, building blocks
Lipids
• Fatty Acids (FAs)– Long non-polar chains of carbon and hydrogen– Monomer for most lipids– Saturated or Unsaturated
• Triglycerides– Common as dietary fat
• Phospholipids– Component of biological membranes
• Steroids & Cholesterol– Important in cell signaling and membranes
• Functions– Energy and energy storage, cell signaling, membranes
Proteins
• Amino Acids (monomers)
• Peptides
• Proteins– Functions
• Enzymes• Structural components• Cell movement• Carrier molecules
Nucleic Acids
• Nucleotides (monomers)– Deoxyribose (DNA) or Ribose (RNA)– Base (A,C,G and T or U)– Phosphate groups
• DNA and RNA Functions– Genetic information– Nucleotides as energy molecules– Assembly of proteins
Products of Metabolism
• Water
• Energy production
• CO2
• Changes in pH– Acid and Base
1.3 Central Dogma of Biology
DNA RNA Protein
• All living organisms have DNA to store genetic information
• RNA is a messenger that carries genetic information
• Protein is the true message
DNA- Stored Information
• “Blueprints”
• A, C, T, G (nucleotides)
• Double-stranded (ds)
RNA- Carriers
• mRNA (messenger)
• rRNA (ribosomal)
• tRNA (transfer)
• A, C, U, G
• Single-stranded (ss)
Protein- Functional Information
• Peptide bonds (covalent)
• Amino acids
• “Beads on a string”
• Proper folding and assembly (form=function)
• Denaturation
Transcription
• The synthesis of RNA under the direction of DNA
DNA 5’- T G C C A T G A A C T C A T G C T A A A T G-3’ 3’-A C G G T A C T T G A G T A C G A T T T A C-5’
RNA 5’- U G C C A U G A A C U C A U G C U A A A U G -3’
Translation
• The production of proteins by decoding mRNA produced in transcription
RNA 5’- U G C C A U G A A C U C A U G C U A A A U G-3’
Met(Start)
Asn Ser Cys *(Stop)
Protein M-N-S-CMet-Asn-Ser-CysMethionine- Asparagine-Serine-Cysteine
DNARNA Protein Interactive
1.4 Cell Review
• Cell: fundamental living unit of any living organism, exhibits all basic characteristics of life– Obtain nutrients from environment to produce
energy
• Metabolism: all the chemical reactions that occur within a cell
Cell Review
• DNA
• Species
• Organelles
• Prokaryotes and Eukaryotes– Alternative spelling procaryotes and eucaryotes
• Cytology
Cell Structure Review
• Prokaryotes– DNA
• Single, Circular Chromosome
• Plasmids
– Ribosomes– Cytoplasm– Cell wall– Plasma membrane– Flagella, pili, endospores– Binary fission
• Eukaryotes– DNA
• Multiple, Linear Chromosomes
– Ribosomes– Cytoplasm– Specialized organelles– Plasma membrane– Mitosis– ~10x larger than
prokaryotes
Metabolism- All the chemical reactions that occur within a cell
• Aerobic– Requires oxygen– Usually produces large
amounts of ATP– Kreb’s Cycle (Citric
Acid Cycle)– Electron Transport
Chain (ETC)
• Anaerobic– Occurs in the absence
of oxygen– Low production of ATP– Glycolysis– Fermentation
• Alcohol production
• CO2 production
– Lactic Acid
Cell Review: Generation Time
• Prokaryotes– Time it takes for binary
fission to occur– ~10 minutes to 48
hours• E.coli 17 minutes• S. aureus 30 minutes• T. pallidum 33 hours
• Eukaryotes– Time it takes for either
mitosis or sexual reproduction to occur
• Yeast 80 minutes• Aphid fly 5 days• Rodents 4 months• Humans 18 years
1.5 Microbial Members & Organization
• Taxonomy: the science of classification of living organisms– Classification: arrangement of organisms into
taxonomic groups (taxa) based on similarities or relationships
– Nomenclature: assignment of names to various taxa
– Identification: process of determining whether an isolate belongs to an established taxa or represents a previously unidentified species
– Bergey’s Manual of Systematic Bacteriology
Five-Kingdom System of Classification
Robert Whittaker (1969)
• Monera: bacteria & archaeans (prokaryotes)• Protista: algae & protozoa• Fungi: fungi• Plantae: plants• Animalia: animals
NOTE: viruses are not included in classification because they are not living organisms
Three Domain System of Classification*
Carl Woese, University of Illinois (1977, 1990)
*Most favored classification by microbiologists, determined relatedness using RNA subunits (16S and 18S) from ribosomes
Microbes
Archaea Bacteria Eukarya
Includes:ProtistaFungi
PlantaeAnimalia
Binomial Nomenclature
• Binomial Nomenclature– Genus (should always be capitalized)– Genus + specific epithet = species– Handwritten names should be underlined– Typed names should be italicized
– Handwritten: Escherichia coli– Typed: Escherichia coli
Binomial Nomenclature (ctd)
• Abbreviations– sp. Designates a single species
• First time written: Escherichia coli • Later written: Escherichia sp.
– spp. Designates more than one species• Clostridium spp. which can include 2 or more:
– C. botulinum– C. tetani