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 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)
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.
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.
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.
