Unit 1: Chapter 1 Microbes Shape our History Flashcards
Microorganisms
Organisms that are too small to be seen with the naked eye; require microscope
What are the two cell types?
Prokaryotic and eukaryotic
Prokaryotes
- Free floating genetic material (cytoplasm)
- NO organelles, so NO compartment function
- Tend to be smaller
T or F: Archaea causes disease
False
Eukaryotes
- Has a nucleus (contains genetic material)
- Has organelles; allows for compartmentalized functions
- Generally larger
- Reproduce using mitosis and meiosis
T or F: Viruses are acellular
True: viruses are NOT made up of cells
What are virus encased in?
Protein coat
What do viruses relay on?
They rely on a HOST CELL for things such as ATP, reproduction, etc
Who built the first compound microscope?
Robert Hooke; came up with the term cells
What did Anton Van Leeuwenhoek do?
He observed bacteria with a single lens microscope and was the first person able to see bacteria
What are some roles of microbes in our life?
- Decompose organic waste
- Ecosystem producers by photosynthesis
- Produce things like ethanol and acetone
- Fermented foods; vinegar, cheese, bread
- Produce products used in manufacturing and disease treatment
T or F: MOST microbes are pathogenic (disease causing)
False; there are very few microbes that are pathogenic
Did the first prokaryotes that appeared use oxygen?
No. The first prokaryotes appeared ~ 3.8 billion years ago and they were anaerobic (did not use oxygen). This is because there was no oxygen around at the time.
What happened when eukaryotes appeared 2.8 billion years ago?
Something called Cyanobacteria. This is oxygenic photosynthesis which is “oxygen produced photosynthesis”. This new oxygen killed a lot of previous organisms that were anaerobic.
After this, many things began to appear such as reptiles, bugs, mammals, and eventually humans.
What did Lynn Margulis propose?
That the first energy-converting organelles of eukaryotic cells (mitochondria and chloroplasts) evolved as a result of endosymbiosis (inside mutualistic relationship); Endosymbitotic Theory
Endosymbiotic Theory of mitochondria and chloroplast
Lynn Margulis proposed that eukaryotes evolved by merging with bacteria to form composite cells by intracellular endosymbiosis, in which one cell internalizes another that grows within it; a single organism who was formally independent is now incapable of existing independently
Respirng bacteria (Proteobacteria) ((similar to E. Coli)) was engulfed by pre-eukaryotic cells where they evolved into mitochondria, the eukaryotes energy-generating organelle.
A phototroph related to Cyanobacteria was taken up by a eukaryote, giving rise to chloroplast of phototrophic algae and plants.
Proved because the DNA sequence was very similar of the origin (respiring to mitochondria; phototroph to chloroplast); both organelles contain circular molecules of DNA which is similar to those of modern bacteria.
How do you classify microorganisms?
Microbes are classified as members of a species according to a shared set of genes and traits
How do you name microorganisms?
The genus is capitalized; the specific epithet is lowercase
After the first use, the scientific names can be abbreviated with the first letter of the genus and the specific epithet
Scientific names are italicized or underlined (if written)
Spontaneous generation
The theory that living microbes can arise spontaneously WITHOUT parental organisms
Basically thought that life comes from thin air; was later proved wrong
Biogenesis
The hypothesis that living organisms arise from preexisting life; the concept that cells do have parents
Spallanzani’s sealed flask experiment
Opponents argued that since the flask was sealed, oxygen was not present and microbes could not grow; they believed that O2 is what caused microbes to grow.
Pasteur’s “swan neck” flask
Pasteur’s “swan neck” flask allowed for oxygen to enter, but the curves in the flask trapped bacteria and dust which kept the boiled contents free of microbes.
When you break the swan neck and expose the contents to the open air, you will notice that microbial growth will occur. This proves that oxygen is not the cause for microbial growth rather its whatever contents is in the air.
This was the experiment that proved spontaneous generation to be false.
Who is considered the “Savor of the Mothers”?
Ignaz Semmelweis
What did Ignaz Semmelweis (1847) do?
Semmelweis ordered doctors to wash their hands with chlorine.
How did Semmelweis find that washing hands lowered mortality rate?
He separated two wards to deliver babys to see if mortality rates change. The first ward was doctors and the 2nd ward was midwives. He noticed that with doctors, they had a higher mortality rate compared to midwives, and one big difference he noticed is that doctors did autopsies while midwives did not.
Doctors would do autopsies and go straight to delivering babies without changing their clothing or washing their hands and this would cause disease to spread. Once doctors started washing hands, mortality rate dropped.
Did doctors listen to Semmelweis when he ordered doctors to begin washing their hands with chorline?
NO; many doctors still refused and thought he was crazy, so he was shunned and sent to a mental institution
Who began to use antiseptic agents (ie. carbonic acid) to treat wounds and surgical instruments after noting that half of his amputee patients died of sepsis?
Joseph Lister (1867)
(this is when cleaning began to catch on)
What did Robert Koch do?
He developed the first scientific method for establishing the microbial cause of a disease
The first to connect a specific disease with a specific microbe; diagnosis for a patient requires evidence that a given microbe causes that disease so this is huge for the world of medicine
The Koch Postulate
- The microbe is found in all cases of the disease, but is absent from healthy individuals.
- The microbe is isolated from the diseased host and grown in pure culture.
- When the microbe is introduced into a healthy susceptible host, the same disease occurs.
- The same strain of microbe is obtained from the newly diseased host.
Is the Koch Postulate still used today?
Yes and no. What he found is not always the case with all diseases.
Ex. E. coli is part of our natural microbiome, but if it gets in the wrong place, then it become bad.
Ex 2. In many cases, you can’t grown microbes in a lab.
Ex 3. The same disease doesn’t always occur when the microbe is introduced to other individuals (ie. covid and flu)
Nowadays we look at the genetic material of the virus rather than growing it.
Variolation vs Vaccination
Variolation is when the same pathogen is introduced into the person in small amounts.
Vaccination is when an attenuated (weak) version of the pathogen is introduced into the body.
Who deliberately infected patients with matter drawn from cowpox lesions and is known as the “Father of Vaccines”?
Dr. Edward Jenner
What is an antibiotic?
A “magic bullet” that only kills the microbe, but leaves the host unharmed
Who discovered the first antibiotic and how?
Alexander Fleming
He came back from vacation and found mold growing on a petri dish of Staphlyococcus bacteria. He noticed the mold was preventing surrounding bacteria from growing, and identified that the mold produced a self-defense chemical that can kill bacteria.
He made this observation, but stopped there with it
What did chemist Florey and Chain do?
They took Flemings observations and purified the chemical the mold produced and used it to treat patients who were dying of bacterial infections. (penicillins)
Mass production of penicillins gave birth to the pharmaceutical industry
