Chapter 1 — Introduction to Microbiology

What is microbiology?

A specialized area of biology that deals with living things ordinarily too small to be seen without magnification.

What are the major groups of microorganisms?

Bacteria, viruses, fungi, protozoa, algae, and helminths.

What is a bacteria?

Category of prokaryotes with peptidoglycan in their cell walls and a single, circular chromosome.

What is a virus?

Acellular, parasitic particles composed of nucleic acid and protein.

What are fungi?

Heterotrophic unicellular or multicellular eukaryotic organisms that can be either macroscopic or microscopic.

What does heterotrophic mean?

Organism that cannot produce its own nutrients; therefore it gets nutrition from other sources of organic carbon, such as plant or animal matter.

What are protozoa?

A group of single-celled eukaryotes that feed on other cells and usually have a locomotor organelle.

What is algae?

Photosynthetic, plantlike (but not considered plants) organisms that generally lack the complex structure of plants. Can be single-celled or multicellular.

What are helminths?

A term that designates parasitic worms such as roundworms and flatworms.

What are the two categories all life can be divided into?

Prokaryotes and eukaryotes.

What microorganisms are considered prokaryotes?

Bacteria (and archaea).

What microorganisms are considered eukaryotes?

Plants, animals, protozoa, and fungi.

Why are viruses considered non-living?

They are acellular, have no metabolism, and they do not grow nor respond to stimuli.

What are the structures of a prokaryote?

Microscopic, unicellular, lack nuclei and membrane-bound organelles.

What are the structures of a eukaryote?

Unicellular and multicellular, has nucleus and membrane-bound organelles.

What does obligate intracellular parasite define?

Defines a virus.

What does taxonomy mean?

Organizing, classifying, and naming living things.

What is binomial nomenclature and what is the correct way to format it?

A genus and a species; Genus + species.

What are the taxonomical ranks in order?

Kingdom, phylum, class, order, family, genus, and species.

What is a hypothesis?

A tentative explanation of what has been observed or measured.

What is a theory?

A collection of statements, propositions, or concepts that explains or accounts for a natural event.

What is a law?

Explains how things happen instead of why (which are what theories are for). Usually is a mathematic equation.

What did Semmelweis contribute to microbiology?

He correlated infections with physicians coming directly from the autopsy room to the maternity ward. Proposed the idea of washing their hands.

What did Fracastoro contribute to microbiology?

Made the idea of “seeds of contagion” and linked symptoms + courses to infection. Mostly known for describing the term “fomite” and being one of the first to suggest the Germ Theory.

What is the germ theory?

A theory first originating in the 1800s that proposed the microorganisms can be the cause of diseases.

What does fomite mean?

Any inanimate object or material that is capable of carrying and transmitting infection.

What did Van Leeuwenhoek contribute to microbiology?

Fashioned the simple single-lens microscope and was able to see microorganisms in a droplet of water; did not invent the microscope.

What did Koch contribute to microbiology?

Developed Koch’s postulates, pure culture methods, and clearly linked one microscopic organism to one specific disease.

What are Koch’s postulates?

1) Suspected microbe must be present in every case of the disease

2) Must isolate and grow pure culture of the microbe

3) Cultured microbe must cause disease when inoculated into a healthy host

4) Same microbe must be isolated from diseased experimental host

What are the exceptions to Koch’s postulates?

Organism can’t be cultured (ex: Mycobacterium leprae), combination of pathogens, and ethical considerations.

What is an example of an organism that cannot be cultured?

Mycobacterium leprae.

What did Snow contribute to microbiology?

Father of epidemiology who rejected the miasma theory. He also identified the source of the Cholera outbreak in London.

What is epidemiology?

The study of disease transmission throughout a population.

What did Lister contribute to microbiology?

Introduced aseptic techniques (heat sterilization) to reduce microbes in medical settings and disinfection of hands using chemicals prior to surgery.

What did Pasteur contribute to microbiology?

Disproved spontaneous generation and proved the theory of biogenesis; showed microbes caused fermentation and spoilage; developed pasteurization; and demonstrated germ theory of disease via the swan necked flask experiment.

What is the swan-necked flask experiment and how did it work?

Pasteur filled flasks with broth and made the openings into swan-necked shaped tubes that were freely open to the air. Any airborne dust particles would deposit in the lower part of the necks to further prove that air and dust were the source of microbes. The broth remained sterile so long as the flask remained intact; however, if the neck was broken off, the broth would be contaminated.

What is spontaneous generation?

An early belief that some forms of life could arise from vital forces present in nonliving or decomposing matter.

What is the theory of biogenesis?

The idea that living things can only arise from other living things.

Up until the 1800s, what did people think disease was caused by?

Miasma.

What did Whittaker contribute to microbiology?

The five kingdom system.

What are the kingdoms of the five kingdom system?

Plantae, fungi, animalia, protista, and monera.

What did Woese contribute to microbiology?

The three domain system via genetic analysis.

What are the three domains in the 3 domain system?

Eubacteria, archaea, and eukarya.

What is genetic analysis?

Looking at gene sequences of the ribosome.

Is archaea considered a prokaryote or a eukaryote? Why?

Prokaryote because archaea do not have nuclei.

Why are archaea more similar to eukaryotes than prokaryotes?

The genetic sequence of the ribosomes of the archaea group have more similarities to eukaryotes.

What is the oldest type of bacteria?

Archaea.

Archaea are considered ______.

Extremophiles.

What is a thermophile?

Heat-loving.

What is a psychrophile?

Cold-loving.

What is an acidophile?

Acid-loving.

What is a halophile?

Salt-loving.

What is a lithophile?

Rock-loving.

What is a barophile?

Pressure-loving.

What is another term for barophile?

Piezophile.

What produces methane?

Methanogens.

What is a reducing atmosphere?

An atmosphere with no oxygen in it (early Earth’s atmosphere); facilitated the formation of organic molecules.

What elements does a reducing atmosphere contain?

Methane (CH4), Hydrogen (H2O), Water Vapor (H20[v]), and Ammonia (NH3).

What is an oxidizing atmosphere?

An atmosphere that contains oxygen (our atmosphere today); hinders the formation of organic compounds.

What elements does an oxidizing atmosphere contain?

Nitrogen (N2), oxygen (O2), and carbon dioxide (CO2).

What is the origin of our present atmosphere on Earth?

Photosynthetic bacteria; cyanobacteria (the reason why oxygen began to be added into the atmosphere).

What measurement is usually used for viruses?

Nanometers.

What measurement is usually used for bacteria?

Micrometers.

What measurement is usually used for protozoa?

Micrometers.

What measurement is usually used for fungi?

Spores are measured in micrometers, but it varies greatly in general (e.g. mushrooms can be measured in millimeters).

What are the differences between eubacteria, archaea, and eukarya?

• Eukarya has a nucleus and organelles, eubacteria and archaea do not.

• Eubacteria and eukaryotes have ester bonds in their cell membranes; archaea have ether bonds (more resistant to extreme conditions) in their cell membranes.

• Archaea are considered extremophiles.

What are the basic research microbiology fields by kind of organism?

Microbial taxonomy, bacteriology, phycology, mycology, protozoology, parasitology, and virology.

What are the basic research microbiology fields by process?

Microbial metabolism, microbial genetics, and microbial ecology.

What are the basic research microbiology fields in relation to disease?

Immunology, epidemiology, and etiology.

What are the applied microbiology fields that are disease-related?

Infection control and chemotherapy.

What are the applied microbiology fields that are environmental?

Environmental microbiology.

What are the applied microbiology fields that are industrial?

Food/beverage technology, pharmaceutical microbiology, and genetic engineering.

What brought about the golden age of microbiology in the late 1800s?

Koch’s postulates because he discovered that a disease can be linked to a microorganism.

What are the phylums/divisions in kingdom plantae?

Angiosperms, gymnosperms, ferns, mosses, and seed plants.

What are the phylums/divisions in kindgom fungi?

Basidiomycetes, ascomycetes, and zygomycetes.

What are the phylums/divisions in kingdom animalia?

Chordates, arthropods, annelids, mollusks, cnidarians, echinoderms, nematodes, flatworms, and sponges.

What are the phylums/divisions in kingdom protista?

Green/red/brown algae, diatoms, dinoflagellates, flagellates, ciliates, amoebas, and apicomplexans.

What are the phylums/divisions in kingdom monera?

Archaea, bacteria, and earliest cells.

What are the features of kingdom monera?

Prokaryotic cells and are unicellular.

What are the features of kingdom protista?

Eukaryotic cells and are simple unicellular and colonial organism; can be photosynthetic (algae) or feed on other organisms (protozoa).

What are the features of kingdom fungi?

Eukaryotic cells with unicellular or multicellular bodies; have cell walls and are not photosynthetic.

What are the features of kingdom plantae?

Eukaryotic cells, multicellular, have cell walls, and are photosynthetic.

What are the features of kingdom animalia?

Eukaryotic cells, multicellular, no cell walls, and derive nutrients from other organisms.

What is an axenic environment?

Environments where microoganisms cannot live (e.g. sterile environments).

What is a bacteria’s doubling time?

About 30 minutes.

What is microbial antagonism?

Bacteria can modify metabolism (can go from anaerobic to aerobic), make toxins (endo/exo-toxins), and make structural modifications.

Which of the following is not considered a microorganism?

a) archaeon

b) bacterium

c) protozoan

d) mushroom

d

An area of microbiology that is concerned with the occurrence of disease in human populations is:

a) immunology

b) parasitology

c) epidemiology

d) bioremediation

c

Which process involves the deliberate alteration of an organism’s genetic material?

a) bioremediation

b) biotechnology

c) decomposition

d) recombinant DNA

d

A prominent difference between prokaryotic and eukaryotic cells is the:

a) larger size of prokaryotes

b) lack of pigmentation in eukaryotes

c) presence of a nucleus in eukaryotes

d) presence of a cell wall in prokaryotes

c

Which of the following parts was absent from Leeuwenhoek’s microscopes?

a) focusing screw

b) lens

c) specimens holder

d) condenser

d

Abiogenesis refers to the:

a) spontaneous generation of organisms from nonliving matter

b) development of life forms from preexisting life forms

c) development of aseptic technique

d) germ theory of disease

a

A hypothesis can be defined as:

a) a belief based on knowledge

b) knowledge based on belief

c) a scientific explanation that is subject to testing

d) a theory that has been thoroughly tested

c

Which early microbiologist was most responsible for developing standard microbiology laboratory techniques?

a) Ignaz Semmelweis

b) Robert Koch

c) Carl von Linné

d) John Tyndall

b

Which scientist is most responsible for finally laying the theory of spontaneous generation to rest?

a) Joseph Lister

b) Robert Koch

c) Francesco Redi

d) Louis Pasteur

d

When a hypothesis has been thoroughly supported by long-term study and data, it is considered:

a) a law

b) a speculation

c) a theory

d) proved

c

Which is the correct order of the taxonomic categories, going from most specific to most general?

a) domain, kingdom, phylum, class, order, family, genus, species

b) division, domain, kingdom, class, family, genus, species

c) species, genus, family, order, class, phylum, kingdom, domain

d) species, family, class, order, phylum, kingdom

c

By definition, organisms in the same _____ are more closely related than are those in the same _____.

a) order, family

b) class, phylum

c) family, genus

d) phylum, division

b

Which of the following are prokaryotic?

a) bacteria

b) archaea

c) protists

d) both a and b

d

Which of the following is not an emerging infectious disease?

a) avian influenza

b) Lyme disease

c) common cold

d) West Nile fever

c