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Chapter 1:

Introduction

2. Brief History of Microbiology

3. Ecological Roles of Microbes

1. Overview of the Microbial World

1. Overview of the

Microbial World

Chapter Reading – pp. 2-7

Evolutionary

Tree of Life

* *

* organisms

covered in

this course

*

(helminths)

Dinoflagellates

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Prokaryotes

Bacteria:

Archaea:

• colonize all but the most

extreme environments

• prokaryotic

“extremophiles”

• chemically and metabolically

very different from archaea

“tongue” bacteria

Methanosarcina

Fungi

Characteristics of Fungi:

• all are eukaryotic heterotrophs (eat “organic” food)

• unicellular (yeasts) or

multicellular (molds, mushrooms)

• cell walls made of chitin

yeast

mold

Volvox

(alga)

Amoeba

Euplotes

Trypanosoma

Protists

Protozoa

heterotrophic protists (“animal-like”)

Protists are mostly

single-celled eukaryotes:

Algae

photosynthetic

protists (“plant-like”)

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Helminths

Helminths =

• invertebrate phyla in the Animal Kingdom

roundworms (Nematodes) &

flatworms (Platyhelminthes)

• many helminths are disease-causing parasites

Trichinella (nematode) “tapeworm” (platyhelminth)

Viruses

Non-cellular,

“non-living” entities.

• cannot metabolize,

reproduce, etc,

without host cell

• frequently

pathogenic

• many consist simply

of a protein “shell” or

capsid which contains

DNA or RNA

Virus

Bacterium

2. Brief History of

Microbiology

Chapter Reading – pp. 7-18

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Anton van Leeuwenhoek was the first to observe

microorganisms in 1673 using his rather

sophisticated (for the time) “magnifying lenses”.

• essentially began the

field of microbiology

• the importance of

microorganisms for

human welfare was not

appreciated until almost

200 years later!

The Discovery of Microorganisms

The Golden Age of Microbiology

Many landmark discoveries in microbiology

occurred in the last half of the 19th century:

• importance of aseptic techniques in hospitals

• Ignaz Semmelweis (1848) – hand washing

• the first epidemiological study (identifying the source of

a cholera outbreak)

• John Snow (1854)

• the first vaccine (cowpox lesions to prevent smallpox)

• Edward Jenner (1789)

• Florence Nightingale (1854) – general cleanliness

• Joseph Lister (~1860) – use of surgical antiseptics

Contributions of Louis Pasteur

• disproved concept of spontaneous generation (1861)

• i.e., microbes do NOT arise from non-living material

• proposed “Germ Theory” of disease (1857)

• showed fermentation

to be carried out by

microbes (1861)

• developed technique

of pasteurization

• developed several

attenuated vaccines

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Contributions of Robert Koch• identified the first bacterial pathogens:

• proposed method to identify the microbial agent

responsible for a given disease (Koch’s Postulates)

• developed numerous advances in

microbiological techniques:

• simple staining methods

• fixation of specimens to slides

• pure culture techniques

• methods for counting microbes

• Bacillus anthracis (anthrax – 1876)

• Mycobacterium tuberculosis (tuberculosis – 1882)

• use of solid growth media

Other Landmarks in Microbiology

• the first synthetic antimicrobial chemicals

• Paul Ehrlich (1908)

• first evidence of viruses (tobacco mosaic virus)

• Dmitri Ivanowski (1892)

• discovery of the first

antibiotic (penicillin)

• Alexander Fleming (1928)

• discovery of prions

• Stanley Prusiner (1997)

3. Ecological Roles

of Microbes

Chapter Reading – pp. 784-787, 795-808

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Microbes & EcosystemsMicroorganisms play many essential roles in

ecosystems, without which life on our planet

would collapse:

Nitrogen fixation• conversion of atmospheric nitrogen (N2) into

“bio-available” ammonia and nitrate compounds

• makes nitrogen available for plants and, indirectly,

all other organisms (necessary for proteins, etc)

Photosynthesis• photosynthetic microbes support aquatic food webs

Decomposition• essential for the recycling of nutrients

Microbes & HumanityMicroorganisms provide many benefits for

human beings:

Internal and external health benefits• gut microbes provide digestive help, important

nutrients, protection from pathogenic organisms

• normal skin and mucosal microbes provide protection

from pathogenic organisms

Food production• wine, cheese, bread, yogurt, etc, depend on microbes

Pollution and pest control• sewage treatment, cleanup of various pollutants, etc

**very few microbes actually cause human disease**

Key Terms for Chapter 1

• heterotroph

• helminth

• protozoa, algae

• archaea

• nitrogen fixation

Relevant Chapter 1 Questions MC: 1, 3, 5, 6, 10

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Chapter 2:

Chemical Principles

2. Biological Macromolecules

1. Atoms & Molecules

1. Atoms & Molecules

Chapter Reading – pp. 27-38

Atomic StructureAtoms are composed of:

Protons (positively charged, 1 amu)

Neutrons (no charge, 1 amu)

Electrons (negatively charged, negligible mass)

nucleus

amu = “atomic mass unit”; atomic mass = protons + neutrons

• # of protons

determines element

• different isotopes of

an element contain

diff. # of neutrons

• electrons (e-) exist in

orbitals, w/in e- shells# of e- = p+ in a neutral atom

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Electron Configurations

Molecules & Covalent Bonds

Atoms share electrons to fill electron shells• sharing of unpaired e- = covalent bond

“Happy” atoms have

NO partially filled

electron shells!

• basis of molecules (multiple atoms joined by cov. bonds)

Molecular weight (MW)

= sum of atomic

masses in a molecule

Water & Hydrogen BondingWater is a polar molecule due to polar O-H bond:

• polar covalent bond = electron pair shared unequally

• nonpolar covalent bond = electron pair shared equally

• hydrogen bonds are weak

interactions between opposite

partial charges due to polar bonds

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Ions & Ionic BondsIons have gained or lost an electron(s),

…and can form ionic bonds

due to the attraction of oppositely charged ions.

Water as a SolventWater’s polar nature makes it

a great solvent for other polar

or charged substances.

• polar water

molecules

neutralize

and shield

the solute

*doesn’t work

for nonpolar

solutes

(e.g., oils)*

Ionic Compounds Dissociate in Water

Acids (release H+ ions), bases (release OH- ions which

then combine with H+), and salts (ionic compounds w/o

OH- or H+) all dissolve and dissociate (split) into ions

very easily in water.

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Acids, Bases & pHAcids release H+

ions into solution

• raise [H+]

• lower pH

Bases remove H+

ions from solution

• lower [H+]• raise pH

pH = –log of [H+]

[H+] x [OH-] = 10-14 M

buffers are molecules

that resist pH change

2. Biological Molecules

Chapter Reading – pp. 39-51

Functional Groups

common molecular groups found in organic molecules

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Carbohydrates

Simple sugars• mono- and disaccharides (e.g., glucose, sucrose)

Complex carbohydrates • polysaccharides (e.g., starch, glycogen, cellulose)

Biological roles: • energy source

• structure, physical support & protection

• adhesion, molecular “recognition”

LipidsHydrophobic (nonpolar)

biological molecules:

• fatty acids

• triglycerides

• phospholipids

• steroids

Biological roles:• membranes, energy source &

storage, communication

Phospholipids & MembranesPhospholipids have “polar heads”, “nonpolar tails”

• form a lipid

bilayer in

water

• the major

component

of biological

membranes

(which have

cholesterol

and proteins

as well)

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ProteinsPolymers of amino acids connected by

peptide bonds (i.e., polypeptides).

• made from 20

amino acids

(differ in their

“R” groups)

• proteins have

extremely

diverse

biological roles

Protein

Structure

Protein function

is entirely

dependent on

protein structure.

Protein structure

is entirely

dependent on

the amino acid

sequence.

1o

2o

3o

4o

Nucleic AcidsDNA, RNA

• polymers of

nucleotides

• store genetic info

• gene expression

ATP• direct source of

energy in cells

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Key Terms for Chapter 2

• valence

• polar vs nonpolar bond

• covalent bond, ionic bond, hydrogen bond

• solvent, solute

• isotope, atomic mass, molecular weight

Relevant Chapter Questions MC: 1-5, 8-10 FB: 1-10 SA: 1-5

• acid, base, salt, pH, buffer

• carbohydrate, lipid, protein, nucleic acid