Figure 1.2 Anton van Leeuwenhoek’s microscopic observations.

Drawings of bacteria

Lens

Location of specimenon pin

Specimen-positioningscrewFocusing control

Stage-positioning screw

Microscopereplica

Van Leeuwenhoek using hismicroscope

From 1683

Types of Microorganisms

• Bacteria

• Archaea

• Fungi

• Protozoa

• Algae

• Viruses

• Multicellular animal parasites

• Taxonomy = classification system

• Linnaeus classification system based upon structural similarities between species.

• Modern classification system based upon evolutionary relationships (determined by DNA sequencing).

• Traditional (including lab manual for 101): Red, brown and green algae are in the Plant kingdom

• Textbook for 101: Red, brown, and green algae are in the Protista kingdom

• UC Berkeley: Red, brown and green algae are in separate kingdoms. (The Protista kingdom does not exist.)

Classification categories• domain – a group of related kingdoms• kingdom - a group of related phyla• phylum (plural = phyla) - a group of related classes. • class - a group of related orders• order - a group of related families• family - a group of related genera• genus (plural = genera) - a group of related species• species - a kind of living organism . All organisms who can potentially reproduce together under natural

conditions and produce fertile offspring.

Most basic cell types:

Prokaryotic: small, simple cells which lack a nucleus and other cell structures

Eukaryotic cells contain a nucleus and internal structures

3 Domains1. Bacteria (prokaryotic)

– Includes blue-green algae

2. Archaea (prokaryotic)3. Eukarya

– The Eukarya are divided into more than 10 Kingdoms: Plants, Fungi, Animals and many others

Figure 10.1 The Three-Domain System.

Bacteria

Mitochondria

Cyanobacteria

Chloroplasts

Thermotoga

Gram-positivebacteria

Proteobacteria

Horizontal gene transferoccurred within thecommunity of early cells.

Nucleoplasm grows larger

Mitochondrion degenerates

Giardia

Euglenozoa

Diatoms

Dinoflagellates

Ciliates

AnimalsFungi

Amebae

Slime molds

Plants

Greenalgae

Eukarya

Extremehalophiles

Methanogens

Hyperthermophiles

Origin of chloroplasts

Origin of mitochondria

Archaea

(DON’T NEED TO KNOW DETAILS)

UC Berkeley Museum of Paleontology 2011: The 12 kingdoms of eukaryotes

(DON’T NEED TO KNOW DETAILS)

Bacteria (a domain)

• Prokaryotes

• Peptidoglycan cell walls

• For energy, use organic chemicals or inorganic chemicals or photosynthesis (cyanobacteria = blue-green algae)

Archaea (a domain)

• Prokaryotic

• Lack peptidoglycan

• Some but not all live in extreme environments. These include methanogens, extreme halophiles, and extreme thermophiles

Fungi (a kingdom)

• Eukaryotes

• Chitin cell walls

• Use organic chemicals for energy

• Most are multicellular (molds and mushrooms) but some are unicellular (yeasts)

Protozoa (not a modern scientific category – includes multiple kingdoms)

• Eukaryotes

• Absorb or ingest organic chemicals

• May be motile via pseudopods, cilia, or flagella

Eukaryotic Algae (not a modern scientific category – includes multiple kingdoms)

• Eukaryotes

• Cellulose cell walls

• Use photosynthesis for energy

• Produce molecular oxygen and organic compounds

Viruses

• Acellular

• Consist of DNA or RNA core

• Core is surrounded by a protein coat

• Coat may be enclosed in a lipid envelope

• Are replicated only when they are in a living host cell

Multicellular Animal Parasites

• Eukaryotes

• Multicellular animals

• Flatworms and roundworms

• Microscopic stages in life cycles

Microbes in Our Lives

• A few are pathogenic (disease-causing) • Decompose organic waste• Many are photosynthetic: produce organic

molecules and oxygen, which are used by animals

• Produce industrial chemicals such as ethanol, acetone and many others

• Produce fermented foods such as cheese, bread, wine and vinegar

Fermentation• Pasteur showed that microbes are

responsible for fermentation

• Some but not all fermentation converts sugar to alcohol

• Microbial growth is also responsible for spoilage of food

Normal Microbiota

• Microbes normally present in and on the human body are called resident flora or normal microbiota

• Normal microbiota help to prevent growth of pathogens

• Normal microbiota produce growth factors, such as folic acid and vitamin K

Figure 1.7 Several types of bacteria found as part of the normal microbiota on the surface of the human tongue.

© 2013 Pearson Education, Inc.

Naming Microorganisms

• Linnaeus established the system of scientific nomenclature

• Each organism is identified by two names: the genus and species

Homo sapiens Canis familiaris

Scientific Names

• Are italicized or underlined– The first letter of the genus name is

capitalized; the species name is not

• Are “Latinized” and used worldwide

• May be descriptive or honor a scientist

Escherichia coli

• Honors the discoverer, Theodor Escherich

• Describes the bacterium’s habitat—the large intestine, or colon

Staphylococcus aureus

• Describes the clustered (staphylo-) spherical (cocci) cells

• Describes the gold-colored (aureus) colonies

Scientific Names

• Scientific names may be abbreviated with the first letter of the genus and the species name: E. coli and S. aureus

(DON’T NEED TO KNOW DETAILS)

• Which is a correct scientific name?a. Baker’s yeast

b. Saccharomyces cerevisiae

c. Saccharomyces cerevisiae

d. S. cerevisiae

The Germ Theory of Disease

• 1876: Robert Koch proved that a bacterium causes anthrax and provided the experimental steps, Koch’s postulates, to prove that a specific microbe causes a specific disease

• An opportunist is a bacteria that does not normally cause a disease, but can become pathogenic under certain conditions, such as immunosuppression

• Nosocomial infection: spread in a hospital or similar location