Microbiology 3050 Evolution and Diversity of Microbial Cells & Domain Eukarya

How do Microbes evolve?

Mutation of genetic material = New genotypes = advantageous phenotypes = natural selection (When the new genotype isn’t advantageous the microbe likely won’t survive)

Silent mutations are …

when a mutation occurs but it doesn’t result in a new genotype or phenotype

Bacteria and Archaea are prokaryotes and they are …

haploid

Why do bacteria and archaea evolve so fast?

Because they are haploid so there is no second copy of a gene to compensate when a mutation occurs AND because they can horizontally transfer genetic information spreading diversity

What was the first organism on earth?

Prokaryotes = Bacteria and Archaea - are now the dominant species in all ecosystems

Why were Prokaryotes the first inhabitants of earth?

Because 4 bya the earth was not a fit environment for much else, the primordial soup, there was also no oxygen until cyanobacteria appeared and starting adding O2 to the environment

How can we tell microbes history a part?

By looking at genes that encode ribosomal RNA —> rRNA because all cells have it

Ribosomes are made up of …

rRNA and proteins

LUCA stands for ...

Last Universal Common Ancestor

Phylogenetic trees for the three domain systems is based on …

the DNA encoding small subunit ribosomal RNA (this the genes that code for a portion of a ribosome, this is how we divide organisms into Bacteria, Archaea, and Eukarya

PCR stands for …

Polymerase Chain Reaction, used to amplify the RNA gene we want and then we copy it

Microbe phylogenetic trees do not use …

Time, instead the length of the lines indicate how closely related two things are, the longer the line compared to another the less related they are

Endosymbiotic theory is …

where mitochondria and chloroplasts were once free living bacteria that were then engulfed and incorporated into other species

Archaea are more similar to …

Eukarya

What two Microorganisms are a part of Eukarya?

Protists and Fungi

Protists include …

algae (makes 75% of earth’s O2), protozoa, slime molds, and water molds

Fungi includes …

yeast and mold

yeast and mold both have what in their cell walls?

chitin

Why does the term species have a different meaning?

because bacteria and archaea do not reproduce sexually (It is not defined as interbreeding natural population)

Microbial species are a collection of …

strains that share many stable properties and differ significantly from other groups of strains

A Microbial strain consists of the …

descendants of a single, pure microbial culture

One strain in a species is designated the …

type strain

An example of two strains of the same species is …

E. coli K12 (worked with a lot in lab, would cause stomach pain and diarrhea but would likely not kill you) vs E. coli O157:H7 (would cause bloody diarrhea kidney failure and potentially death)

The strain designation comes …

after the genus and species and it isn’t italicized

Why are microbes the most diverse and populous group of organisms?

because they have been on the planet the longest

Where are most microbes found?

underground

Microbes contain a major fraction of …

biomass and key reservoirs of essential nutrients, like carbon cycling and many other cycles

Microbes influence …

ALL living things

Most microbes are beneficial or …

benign, meaning they help us or do nothing to us, other life forms require them for survival

Some microbes are hurtful or …

detrimental like pathogens

Microbes are excellent tools for …

study since they grow so quickly, we can watch evolution through them

How do microbes influence humans?

they are apart of agriculture like how helpful they are in breaking down food in the rumen of a cow, our food like yeast, energy (used for making ethanol), in the human gut, cycling nutrients, the environment (some are used to break down harmful things in ecosystems), and diseases

Why have diseases by microbes gotten less severe?

Because we are continuing to develop drugs, better sanitation, and antibiotics

Robert Hooke described what?

Fruiting structures of molds and he coined the term cell

Antony van Leeuwenheok was the first to observe …

and accurately describe bacteria, he sketched bacilli and movement of bacteria

What is spontaneous generation?

the idea that living organisms can develop from non-living organisms or decomposing matter (believed to be true but eventually discredited)

Francesco Redi discredited …

spontaneous generation for large animals, he did an experiment where he left 3 jars with meat, one was sealed, one was covered with gauze and the last was left open

What happened to Redi’s jar that was sealed?

nothing, no maggots or other creatures ended up getting to the meat, and it took longer to rot

What happened to Redi’s jar that was covered in gauze?

maggots and flies grew on top of the gauze

What happened to Redi’s jar that was open?

rotted quickly and was infested by maggots and flies

Who disproved spontaneous generation?

Louis Pasteur

What experiment did Louis Pasteur do?

sterilized a liquid with extensive heat inside a flask with a curved end, steam was forced out through the open end creating a u-trap, microorganisms and dust were trapped in the bend and the liquid remained sterile, after turning the flask and letting the liquid go around the bend the liquid putrefied (rotted)

Put simply, Louis Pasteur proved that …

for something to occur the solution or item has to come in contact with “something” for it to rot

Pasteur also demonstrated that microorganisms carry out …

fermentation, his discoveries led to the development of microbial control methods like pasteurization and aseptic technique

Pasteurization decreases …

microbes in a product

What is aseptic technique?

a set of specific practices and procedures used in healthcare and laboratories to prevent the contamination of sterile environments and protect patients from harmful pathogens, often involves using a flame

Louis Pasteur developed vaccines for …

anthrax, chicken cholera, and rabies, did so by accidentally giving chickens a weakened strain of cholera so they did not present the infection but their immune systems learned to combat it, so when they were exposed to the more lethal strain they lived

Louis Pasteur also solidified the …

germ theory of disease, the scientific principle that specific microscopic organisms, known as pathogens or "germs," invade the body and cause infectious illnesses

Ignaz Semmelweis told a hospital that to prevent childbed fever, women were dying after giving birth, doctors need to …

wash their hands, they were coming from the morgue, he noticed because when mid-wives delivered the mother did not get sick, no one believed him and he was sent to a mental institution

Joseph Lister is called the father of modern surgery because …

he developed a system of surgery to prevent microbes from entering wounds, his patients had fewer postoperative infections

Robert Koch established the relationship between …

Bacillus anthracis and anthrax, (this specific species and the illness it contracts) as well as for Mycobacterium tuberculosis and tuberculosis and vibrio cholerae and cholera

Koch’s Postulates is still used today to establish …

the link between a particular microorganism and a particular disease

What is the first postulate?

the suspected pathogen must be present in all cases of the disease and absent from healthy animals

What is the second postulate?

The suspected pathogen must be grown in pure culture

What is the third postulate?

Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal

What is the fourth postulate?

The suspected pathogen must be reisolated and shown to be the same as the original

In order to complete the second step of postulates we need to be able to …

grow bacteria with agar (a solid media)

Step 1 of Koch’s Postulates requires …

microscopy

What are some things that make Koch’s postulate difficult to use?

asymptomatic infections, when we can’t grow the bacteria in question in a lab

Walter’s wife came up with using …

agar, it wouldn’t melt like gelatin would at 37 C or get eaten by the bacteria and liquify it, she used it for her jams and jellies

What do we need to be able to obtain and grow bacteria in pure cultures?

nutrient broth, nutrient agar, petri dishes, and streak plating technique to isolate colonies

Why do we incubate bacteria upside down?

to keep condensation from falling on the bacteria

Who used a vaccination procedure to protect individuals from smallpox?

Edward Jenner (1798) he took puss from a blister of a cow with cow pox and exposed himself, his wife, children and the gardener’s children

Ferdinand Cohn was a botanist so he uses a lot of plant morphology, but he discovered …

Endospores, and he classified bacteria based on shape

Alexander Flemming discovered …

Penicillin, by “accident,” an agar plate was left out and fungi grew on it and no bacteria grew within some space of the fungi which we learned is because the fungi produces penicillin

Ferdinand Cohn also thought that bacteria were …

plants

Martinus Beijernck described the first …

virus, has a stube and something was still passing through it that was smaller than bacteria, he also pioneered the use of enrichment cultures and selective media and isolated the first pure cultures of many soil and aquatic bacteria

What is selective media?

Selective media are specialized growth media designed to suppress the growth of unwanted microorganisms while encouraging the growth of specific target organisms

What is enriching cultures?

increases the population of a specific microorganism from a complex, mixed sample, rather than isolating the organism immediately, this method creates custom conditions that give the target organism a strong competitive advantage, allowing it to multiply and outgrow other species in the sample

Sergei Winogradsky discovered …

numerous interesting metabolic processes including anaerobic fixation and he proposed the concept of chemolithotrophy (eating rocks)

Watson, Crick, and Franklin discovered …

DNA structure

Sanger/Woese discovered …

the tree of life/DNA sequencing

Kary Mullis discovered …

PCR

Handelsman discovered …

metagenomics (extract everything in DNA sequence it and see what is and isn’t there. often used instead of Koch’s postulates)

Griffith’s famous experiment =

“cracking the code of life” - the rat experiment that demonstrated transformation using horizontal gene transfer and S and R strain bacteria