MICROBIOLOGY

History and Types of Cells

Chapter 1

Nester 2nd Ed.

History

Cartoons Ancient descriptions of diseases

• Chinese writings• Egyptian papyrus writings• Bible

Microorganisms seen about 325 years ago. Microbiology is only 130 years old.

Anton van Leeuwenhoek - 1674

Drapery merchant Made ground glass lenses - magnified 300X Figure 1.2 p. 3 simple microscope Figure 1.1 p. 3 drawings of microorganisms Described animalcules Question: How did these organisms

originate?

Francesco Redi - late 1600’s

Disproved spontaneous generation for visible organisms

Figure - Classical Jar Experiment Gauze did not prevent microorganisms in

the air from entering the jars. The meat in the gauze covered jar rotted but

did not produce maggots.

John Needham - 1749

Made broths (infusions) of many things• hay, beef and chicken• in other words - soup

Heated broths in flasks; then sealed flasks All his broths still be came turbid (cloudy). Microorganisms “got in” the flasks. Pro-spontaneous generation

Father Spallanzani - 1700’s

Boiled his infusions longer Sealed flasks Got no growth Anti-spontaneous generation Had no real explanation

None of these people considered:

The flasks were improperly sealed. There were organisms in the air. Boiling might not kill all organisms. Standardization would be beneficial.

Louis Pasteur - 1861

He did the classic experiment that refuted spontaneous generation.

Figure 1.4 p. 5 swan-necked flask He trapped microorganisms on a cotton plug

and observed them microscopically. An organism, on a cotton plug dropped in

sterilized infusion, caused the broth to become turbid.

John Tyndall - 1876

He provided a logical reason for the discrepancies of previous workers.

He heated infusions for varying lengths of time.

He proposed that there were heat resistant life forms.

Endospores were discovered the same year.

Cell Theory

Schleiden Schwann Virchow All organisms are composed of cells. The cell is the fundamental unit of life. All cells come from preexisting cells.

Similarities of All Cells

Structure - genetic material, plasma membrane, cytoplasm

Replicate exact copies of DNA Have genetic instructions for synthesis of its

parts Obtain and use energy

Prokaryote versus Eukaryote

Prokaryote = pre-nucleus Eukaryote = true nucleus Table 1.3 comparison of these two groups

Prokaryotes

Eubacteria• true bacteria

• diverse group

• rigid cell wall

• contains the pathogens

• Table 1.4 major groups

Archaea• primitive bacteria

• diverse group

• variable cell wall

• now thought to be the most common bacteria on earth

• found in many environments

Prokaryotes

Both Eubacteria and Archaea are similar by microscopy and how they are classified.

Eubacteria and Archaea differ biochemically.• RNA’s• Enzymes• Nutritional requirements• Environments where they grow

Intermediate Cells

Figure 1.7 p. 12 Giardia intestinalis• nucleus• no mitochondria

Figure 1.8 p. 13 Gemmata obscuriglobus• membrane-bound nuclear body• no other membrane-bound organelles

Other Members of the Microbial World - Eukaryotes

Algae• unicellular or multi-cellular• Figure 1.10 p. 15

Fungi• usually multi-cellular• some single cell forms• Figure 1.11 p. 15

Other Members of the Microbial World - Eukaryotic

Protozoa• single cells• Figure 1.12 p. 16

Table 1.5 p. 15 comparison of algae, fungi, protozoa

Other Members of the Microbial World - Non-living

Viruses • nucleic acid plus protein and lipid• Figure 1.13 p. 17

Viroids• naked nucleic acid• Figure 1.14 p. 17

Other Members of the Microbial World - Non-living

Prions• self replicating proteins• may be weird viruses or viroids• replication is a mystery

Table 1.6 p. 16 comparison of viruses, viroids, prions

Sizes of Microorganisms

Figure 1.16 p. 18 comparison of sizes Perspective 1.3 p. 12 largest prokaryote

Nomenclature - Naming

Binomial system - two names similar to the system developed by Carl von

Linne• changed his own name to Carolus Linneus

K, P, C, O, F, G, S, V

Nomenclature

Genus - 1st word is capitalized Species - 2nd word is lower case

• Escherichia coli or E. coli• Legionella pneumophila or L. pneumophila

Member of the same species can vary in minor ways• strains or varieties• E. coli K-12, E. coli ML