BIOL 3200 - Exam 1

Microbiology Exam 1

Microbes

a living organism that requires a microscope to be seen

What are the exceptions to Microbes?

1. Supersize microbial cells

2. Microbial communities

3. Viruses

Robert Hooke

1. built the first compound microscope

2. coined the term “cell” after observing a cork

3. observed mold

4. published Micrographia, which was the first manuscript that illustrated objects under the microscope

Anton Van Leeuwenhoek

1. built single-lens magnifiers, complete with a sample holder and focus adjustment

2. first to observe single-celled microbes and called them “small animals"

3. a cloth draper

Francesco Redi

1. showed that maggots in decaying meat were offspring of flies

John Needham

Lazzaro Spallanzani

1. showed that a sealed flask of meat broth sterilied by boiling failed to grow microbes

Louis Pasteur

1. devised “swan-neck” flasks

2. showed that after boiling, the contents remain free of microbial growth, despite access to air

3. disproved spontaneous generation

4. proposed Biogenesis

5. developed the first vaccines based on attenuated (weakened) strains

   • Fowl cholera aka chicken cholera = bacterial disease

   • Rabies = viral disease

Mr. Onesimus and Lady Montagu

1. immunization through innocuation, which was the process of immunizing someone against a disease by introducing infective materials or microorganisms into the body

2. Onesimus = African slave, introduced into the American Colonies

3. Montagu = introduced to Europe from Turkey

Edward Jenner

1. deliberately infected patients with matter from cowpox lesions

2. practice of cowpox innoculation was called vaccination

Florence Nightingale

1. first to recognize disease in warfare

2. showed the deaths of soldiers due to various causes, she devised the “polar area chart”

Robert Koch

1. german physician and founder of the scientific method of microbiology

2. applied methods to numerous lethal diseases around the world - known as the Koch’s Postulates

   1. Microbe is always present in diseased host - not always true

      • absent in healthy - immune system (could appear helthy, but not actually health)

   2. Microbe is grown in pure culture - not always true

      • no other microbes present - majority of microbes do not grow in a media

   3. Introduce pure microbe into healthy host - not always true

      • individual becomes sick - immune system (could not be affected)

   4. same microbe re-isolated from now-sick individual - usually true

Ignaz Semmelweis

1. ordered doctors to wash their hands with chlorine, an antiseptic agent

   • mortality rates of woman in childbirth fell

Joseph Lister

1. developed carbolic acid to treat wounds and clean surgical instruments

   • from this, aseptic surgery was developed - environments completed microbe-free

Alexander Fleming

1. rediscovered that Penicillium mold generated a substance that kills bacteria

   • Later, Howard Florey and Ernest Chain purified penicillin (first commerical antibiotic to save human lives)

Sergei Winogradsky

1. Russian scientist who was among the first to study microbes in natural habitats

2. Discovered lithotrophs (feed on inorganic minerals)

3. Developed enrichment cultures

4. Built the Winogradsky column

   • a wetland model ecosystem containing regions of enrichment for microbes of diverse metabolism

Carolus Linnaeus

called the microbial world “chaos”

Lynn Margulis

1. proposed mitochondria and chloroplasts, evolved by endosymbiosis from prokaryotic cells engulfed by pre-eukaryotes

   • proposed the endosymbiosis theory - species evolved from more than one ancestry

     • mitochondrial and chloroplast DNA

       • has double membrane

       • has own DNA very similar to Bacterial DNA

     • mitochondrial and chloroplast ribosomes

       • ribosomes usually on rough ER for human cells, here they are much closer related to Bacterial ribosomes

     • size and morphology

Carl Woese

1. studying recently discovered prokaryotes that

   • live in hot springs

   • produce methane

2. analysis of the DNA that codes for SS rRNA revealed that these prokaryotes were a distinct form of life

   • he and George Fox, called them archaea (based on rDNA sequence, archae are similar to eukarya)

Rosalind Franklin

used x-ray crystallography to determine that DNA is a double helix

What difficulties did early taxonomists encounter when attempting to classify microbes?

1. Resolution of the light microscope was too low

   • Challenge was overcome via advances in biochemistry and microscope (ex: gram positive and gram negative)

2. Microbial species are hard to define

What type of organisms are included under the kingdom Protista?

1. microbes are neither plant nor animal

   • protista = Monera

2. Later, Monera was divided into two groups

   • Eukaryotic protists (protozoa and algae) = nucleus

   • Prokaryotic bacteria = no true nucleus

What are the five kingdoms proposed by Robert Whittaker?

1. Kingdom of Protists

   • more of a miscullaneous group

2. Kingdom of Monerans

   • more of a miscullaneous group

3. Kingdom of Fungi

4. Kingdom of Plants

5. Kingdom of Animals

What is the endosymbiotic theory?

A theory that states that mitochondria and chloroplasts evolved from free-living prokaryotic cells that were engulfed by early eukaryotic cells and became permanent organelles.

• Evidence: Mitochondrial and Chloroplast DNA, Mitochondrial and Chloroplast Ribosomes, and the size & morphology

How was the ‘Three Domain’ Classification of Life determined?

1. Woese’s discovery grouped the five kingdoms to three equally distinct groups (domains)

   1. Bacteria

   2. Archaea

   3. Eukarya

2. In the three-domain model:

   • Mitochondria derived from proteobacteria (aka pseudomonadota)

   • Chroloplasts derived from cyanobacteria

What arguments support the classification of Archaea as a third domain of life?

1. Archaea DNA sequence

2. Introns are common

3. RNA polymerase: Eukaryotic homologs

4. Transcription factors: Eukaryotic homologs

5. Resistant to ribosome sensitivity to chloramphenicol, kanamycin, and streptomycin

6. Translation initiator: Methionine (except mitochondria and chloroplasts use formylmethionine)