Introduction to Microorganisms 1

Lesson Objectives: – Define microbiology. – List the organisms included in the field of microbiology. – Discuss the role microorganisms play in the environment, the food industry and the medical field. – List the distinguishing characteristics of bacteria, fungi, algae, protozoa and viruses. – Describe how bacteria are named. – List the microorganisms that are classified as prokaryotes and eukaryotes.

Microbiology The study of living organisms too small to be seen with the naked eye. Question: (with a partner) What event, discovery, or invention marked the start of Microbiology? Answer:________________________________

Members Bacteria Fungi ( yeasts and molds) Protozoa Algae Viruses

Prokaryote Cell

Cellular Organization Prokaryotes-Pre nucleus – Bacteria – Simple cells – Small – No membrane- bound nucleus. DNA is organized into one large circular strand (genome) and smaller circles (plasmids) – No membrane-bound internal structures (ribosomes present) – Cell division quick-Binary Fission

Eucaryote

Eukaryotes True (good) nucleus Membrane bound organelles Includes fungi, algae, and protozoa, plants and animals More structurally complex Cell Division is by mitosis and meiosis

Microbes and the Planet First life on the earth Prokaryotes (bacteria) appeared about 3.5 billion years ago Eukaryotes ( all other microbes) arose 2 billion years ago Ubiquitous – Adaptable to any niche that exists

Microbes and the Planet Essential for life – Photosynthesis Microbes are responsible for over 70 % of Earth’s photosynthesis – First photosynthesis—did not produce oxygen! When oxygen was formed, an environment suitable for man and animals resulted. Earth’s environment is a result of microbial products soil water atmosphere

Scope of Microbiology Environmental Most microbes are beneficial – Genetic engineering – Bioremediation – Food production – Symbionts—provide necessary processes to other organisms.

Microorganisms and the Environment Decomposition-recyclers of nutrients Can breakdown complex organic compounds to simple compounds Return CO 2 N 2, and H 2 0 to atmosphere and soil

Scope Food Microbiology Examples of food made possible by microbes:

Microbes and Man Normal floraPathogens Found in which parts of body? Approximately what percentage of microbes are pathogens?

Figure 1.5 Medical Antibiotics fungus Why is there a clear zone here?

Classification and Nomenclature Names were originally based on visible characteristics of microbes: Microscopic appearance (Staphylococcus—”bunch of grapes,” Bacillus—”rod”) Discoverer of the organism or the disease (Salmonella: Daniel Salmon, Listeria: Joseph Lister) ??????????? (Pseudomonas: “false monad”)

Taxonomy: O rganizing, Classifying and Naming Living Things Formal system originated by Carl von Linné ( ) Concerned with: – classification – orderly arrangement of organisms into groups – nomenclature – assigning names – identification – discovering and recording traits of organisms for placement into taxonomic schemes

Woese System of Classification Carl Woese compared a macromolecule found in all cells (rRNA) and used the sequence of bases in this molecule as a basis of comparison in thousands of organisms.

Why use ribosomal RNA 1.Every organism on the planet has rRNA, and it always has the same function. 2.The sequence of nucleotides (adenine, guanine, cytosine, uracil) in certain parts of rRNA undergo very little change throughout evolution. Therefore… 3.All members of a given species have the same rRNA sequence (in certain areas).

Woese’s conclusion Three major “domains” of living cells: Bacteria Archaea Eukarya The first two are prokaryotes, the third is all eukaryotes Bacteria and Archaea are as different from each other as each is from Eukarya

Nomenclature Binomial Latinized Genus-noun Species-adjective Genus (always capitalized) species (never capitalized) – Staphylococcus aureus – S. aureus – S. epidermidis