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