Chapter 1: Microbial life origin and discovery

What is a microbe and some characteristics of it?

A microbe is a microscopic organism such that are typically unicellular but can be multicellular.

• contains genome used to reproduce its own kind

• cannot regulate internal temp

What is the size range of a microbe?

0.2mm to 5mm

What do microbes include?

• prokaryotes: bacteria, archaea

• eukaryotes: algae, fungi, protists

• viruses: noncellular particles

What are the 3 domans of life?

bacteria, archaea, and eukaryotes

What is a genome

the total genetic information contained in an organisms chromosomal dna

Who developed the first method of dna sequencing?

Fred Sanger sequenced haemophilus influenzae

What is a metagenome?

DNA of all microbes in a community or environment

What are 3 examples of microbes affecting human history in positive and negative ways?

• yeasts and bacteria gave use fermented food and alcohol but spoils meat and wine

• Lithotrophs aided metal mining but deteriorate ancient stone monuments

• microbes of all times have caused disease and famine

What are four microbial diseases that have devestated human populations?

• Yersinia pestic: the plague

• Mycobacterium tuberculosis: tuberculosis

• HIV: aids

• SARS-CoV-2: Covid-19

Who was florence nightingale and what did she do?

• founder of professional nursing and medical statistics

• recognized significance of disease in warfare

• Devised the polar area chart

What did robert Hooke do?

built the first compound microscope and coined the term “cell”

What did Antonie van Leeuwenkoek do?

built the single lens magnified and was the first to observe single cell organisms

• established microbiology as a discipline

What was the theory of spontaneous generation?

A theory that living creatures such as flies could arise spontaneously without parents

how was spontaneous generation disproved?

Louis Pasteur did an experiment with a swan-neck flask which proved that the boiled broth did not grow microbes until exposed to the trapped microbes in the water of the neck

What was the overall contribution of Lous Pasteur?

• discovered biochemical basis of microbial growth

• founder of medical microbiology and immunology

What did Robert Koch contribute?

• founder of scientific method of microbiology

• provided proof of germ theory of disease: many diseases are caused by a specific pathogen (not all:diabetes)

Who developed the petri dish?

Julius Petri made the double sided petri dish

Who developed agar?

kochs colleagues Angelina and Walther Hesse

• made from red seaweed a polymer of sugar galactose

What are Kochs postulates?

an ordered set of criteria to establish a causative link between an infectious agent and a disease

• suspected microbe always present in diseased host and absent in healthy

• Suspected microbe is isolated and grown in pure culture outside host without other microbes present

• Introduce pure microbe into healthy hosts and individuals become sick with same disease as original host

• same microbe now re-isolated from sick individuals

What did Koch test his postulates on?

Anthrax from bacillus anthracis

Who made the first vaccine and how?

• Dr Edward Jenner

• cowpox infection protects patients from smallpox

How did louis pasteur make vaccines better?

developed vaccines with attenuated strains of microbes that could pass through immune system without harming it

Who disovered the first antibiotic?

alexander Fleming

• penicillin

What is penicillin?

an antibiotic created by penicillium notatum

Why was antibiotics a revolutionary discovery at the time?

saved lives of allied troups during WW2

who discovered viruses?

Dmitri Ivanovsky

How were viruses discovered?

Ivanovsky studied tobacco mosaic disease and realized it could pass through a .1 filter (much smaller than bacteria)

What did Beijerinck do?

proposed that the causative agent of tobacco mosaic disease was not a bacteria

• he termed to coin virus!

What did Wendell Stanley do?

Purified and crystallized the causative agent of tobacco mosaic virus

Tobacco mosaic virus

• the proteins capsids surround the RNA chromosome

Why are microbes important to earth?

they cycle many nutrients necessary for life

• ex) ALL N2 and most O2 on earth

Who was sergei winogradsky and what did he do?

a microbiologist that was among the first to study microbes in natural habitats

• built the winogradsky column to study it! it was a model of a wetland ecosystem

• discovered lithotrophs

• Developed enrichement cultures

How did the Winogradsky column work?

most oxygen at top and none at the bottom. slowly decreased down the pipe

• thus aerobes would grow at the top and anaerobes would grow towards the bottom

What are lithotrophs?

organisms that feed solely on inorganic material

What are enrichement cultures?

the use of selective growth media that support certain classes of microbial metabolism while excluding others

what are endosymionts?

microbes that live inside a larger host organism

What is an example of endosymbiosis in plants?

the bacteria Rhizobium induce the roots of legumes to form nodules and they go into them and facilitate bacterial N2 fixation

What is an example of endosymbiosis in animals and insects?

require bacteroides to break down cellulose in their digestive system

What is an example of endosymbiosis in humans?

human instestines containt Escheria coli and bacteroides that grow as a biofilm and contribute positively to human health

what is a biofilm?

organized multispecies community adhering to surface (colonic epithelial cells)

What were the 5 kingdoms Robert Whittaker generated?

• bacteria

• protists

• fungi

• plants

• animals

How did Carl Woese change the 5 kingdom system?

• he discovered prokaryotes that lived in hot springs and produced methane

• did a 16S rRNA and revealed these as a distinct form of life

• they were archaea!

What is the origin of mitochondria?

ancient proteobacteria

What is the origin of chloroplasts?

anciet cyanobacteria

What did Rosalind Franklin do?

discovered DNA is a double helix by an xray diffraction pattern

What did Watson and Crick do?

discovered complementary bases and antiparallel structure of DNA

What did Thomas Cech do?

discovered catalytic rna

What is catalytic RNA?

Catalytic RNA, or ribozymes, are RNA molecules that have the ability to catalyze chemical reactions, similar to protein enzymes.