week 1 (unit 1) Flashcards
2 types of organisms
cellular and acellular
4 groups of cellular organisms
bacteria, archaea, fungi, protists
4 groups of acellular organisms
viruses, viroids, prions, satellites
Woese discovered that archaea are more closely related to…
eukarya
bacteria characteristics
single-celled, cell wall with peptidoglycan, lack membrane-bound nucleus, extreme environments, does and does not cause disease
archaea characteristics
unique rRNA sequences, unique membrane lipids, unusual metabolic characteristics, extreme environment, does not cause disease (to humans bc we don’t live in the same environment)
eukarya characteristics
membrane-enclosed, larger, more complex,
- protists: unicellular, larger
~protozoa: animal-like
metabolism
~algae: photosynthetic
- fungi: ~unicellular (ex: yeast)
~multicellular (ex: mold,
mushrooms)
Virus charcteristics
when was life first identified on Earth?
3.5-3.8 bya
how can life be traced that far back?
through carbon dating, fossils, and molecular fossils (hopanes), prokaryotes
stromatolites
they are photosynthesizers, abt 3.5 byo, mineralized layers of cyanobacteria
when did the Oxygen Revolution happen?
abt 2.5 bya
what was the Oxygen Revolution?
early earth lacked O2 and so when O2 began rising it led to the extinction of many prok, but some did survive and they had adapted to an anaerobic environment (meaning they dont NEED O2 to survive). Some used cellular respiration to harvest energy
What is endosymbiosis?
when an org lives in another org
Endosymbiotic Theory
origin of mitochondria, chloroplasts, and hydrogenosomes,
~our mitochondrial DNA may be
more similar to bacteria than to the
DNA in our other cells
LUCA (last universal common ancestor)
the 3 domains of life originated from, archaea and euk diverged from a common ancestor and bacteria evolved independently
how do b,a, and e reproduce?
a and b - horizontal gene transfer
e - sexual reproduction (aka vertical gene transfer)
microbial taxonomy
phylum
class
order
family
genus
species
strain
~ fgspecies- 16s rRNA sequencing
~strain- shotgun metagenomic sequencing
Why use 16s rRNA sequencing?
It is highly conserved in a and b and that sequence is present in all strains
what evolved from prokaryotes?
ribosomes, cytoplasm, cell membrane, and metabolic pathways
Lucretius
he said there are good and bad things
fracastoro
he came up with “spores” and believed there were little things that were causing disease
Hooke
-coined the term “cell”
- made the best compound microscope and illumination system
- book: Micrographia
Anton
- 1st to observe single-celled organisms (animalcules - little animals)
Spontaneous Generation (I’ll abv as SG)
the idea that living organisms can come from nonliving or decomposed matter
4 men involved in SG
reddi, needham, spallanzani, pasteur
Reddi
- disproved SG
- meat left overnight, COVERED did not result in maggots being on the meat therefore the meat must be EXPOSED to be contaminated
Needham
- supported SG
- boiled hay, left it overnight UNCOVERED, and it had growth of something in there
Spallanzani
- disproved both SG and Needham
- did Needham’s experiment again except he COVERED the flask and there was no growth found. Thus proving that the hay being EXPOSED is what gave way for it to be contaminated
Pasteur (high priest of microbio)
- disproved SG
- in a swan neck flask, microbes at being boiled and it there was only growth in the broth when the flask was broken
- thus again proving that when EXPOSED, it will become contaminated
Pasteur’s Germ Theory
- disease caused by microbes
- each microbes causes a specific disease
- susceptibility depends on many factors such as: the infecting agent, environment, and the specific host
4 criteria for Koch’s postulates
The microorganism must…
1. be present in all diseased and absent from all healthy org
2. be able to be isolated from the diseased host and grown in pure culture
3. cause the same disease when inoculated din a healthy host
4. must be isolated again from diseased host and identified as the same as what was inoculated
limitations of koch’s postulates
- some orgs cant be grown in a pure culture due to relying on the host cells to grow
- cant find an animal model (and we cant use human models so)
Jenner
this guy proved that diseases were infectious by getting cowpox fro a postu;e and injecte dit into a healthy kid an dthen that kid got sick
- used vaccination procedure against smallpox
Lister
- developed an antiseptic system that prevented microorg from getting in the wounds
- thus indirectly proving that microorg caused diseases
-lactic fermentation -> milk souring
Fleming
- discovered penicillin -> fights against staph
type of culturing medias
selective and differential
selective media
promotes the growth of a particular microbe but inhibits the rest
- so half side: growth and the other half: nothing
differential media
distinguish different groups of microbes from their biological characteristics
- so we could be seeing a response with color like based on the characteristics of metabolism it colored it pink
7 types of microscopy
brightfield, darkfield, phase-contrast, DIC, confocal, fluorescence, electron (SEM and TEM)
brightfield
- image with a light background
- unstained or stained
- light is being absorbed
darkfield
- bright image with a dark background
- unstained, internal structures in euk
- light scattering
phase-contrast
- observes microbial movement and detect structures
- living, no fixing or staining required
DIC
adds contrast which helps observe endospores, cell walls, granules, vacuoles, and nuclei
flourescence
- shows localization of a specific proteins in the cells
- it removes part of the stop codon and replacing it with GFP and tags the specific molecules so we can track it
confocal
it uses lasers and makes a 3D image of specimens in biofilms
electron
- this kind of microscopy uses electrons instead of light
- more detailed results
- SEM: realistic 3D image of surface structures
- TEM: realistic 3D image of internal structures
2 ways to prepare a specimen
fixation and staining
2 ways of fixation
- heat: preserves morphology but destroy steh subcellular structures
- chemical: protects both the fine cellular structures and morphology
2 ways of staining
- gram (+)
- gram (-)
3 plating techniques and overall method
- streak- streaks in different directions and sterilize the streaker in between each step
- pour- pipette the bacteria first and then pour the agar and swirl
- spread- pipette the bacteria onto the agar and and spread evenly using the spreader
4 steps of gram-staining
- crystal violet solution
- iodine solution (all will be stained purple)
- decolorize acetone ( the gram (-) are now colorless)
- safranin counterstain (now the gram(-) will be stained red)
—- between each step you rinse the previous chemical off
