Module 1: History of Microbiology and Microscopy Flashcards
what are Eukaryokes
large multicelluar microorganisms
what is microbiome
coexisting vast number of colonizing microorganisms
- vast majority are not harmful to us but play essential roles in providing nutrients, carrying out essential transitions and cycling of nutrients
what is the average size of microorganisms
0.2 mm and smaller
are paracites considered microorganisms
yes
what other entitities are considered micro organisms even though they cant live on their own
viruses and prions
how do we know that cellular life on earth is all related to one another
DNA sequencing analysis allows for comparisons of the DNA sequence changes between each species
- many scienctists have worked to obtain sequences from the same gene From every known organism and shared it on a data base
what is is called to obtain sequences from the same gene?
phylogenetic analysis
what are the three domains of life
bacteria, archaea, and eukarya
what are viruses
- the smallest of the microbs
- they cannot replicate on their own, they require host cells to replicate
- they can encode their own genetic DNA or RNA
- we cannot determine how related they are to cellular life becasue they do not share genes that are consistenly in other life forms
- viruses can cause a number of human diseases and cancers
what are viroids
- require host cells to replicate
- they replicate their genomes (single stranded RNA)
- spread from cell to cell
- they are limited to plants
what are satellites
- a defective virus
- they encode a nucliec acid enclosed in a protein shell and infect new cells on their own
- they cant replicate themselves unless the cell they are in is coeffected with a specific virus that provides enzymatic help to complete their life cycle
what is a prion
- proteins encoded by the host
- infectious variants of this protein misfold to create a new form that has a tendency to bind to other copies of the normal protein and cause them to misfold
- this can cause normal copies to fold
- this can effect foods and if foods are consumed by humans it can begin the process in a human host
what was a major player of early life
RNA - serving as both a genetic informer and carrying on essential catalytic functions
all living cells have a collective set of atributes
- they are made up of cells
- ability to respond to environmental changes
- ability to grow and develop
- use energy and undergo metabolism
- regulate cellular metabolic activites
- reproduce
- undergo biological evolution
which of the collective set of attributes is most important
biological evolution
what can all life forms be traced back to?
LUCA
L last
U universal
C common
A ancestor
what was the first domain to exsist
evidence points to Bacteria and Archaea
with eukaryotes developing later
- both cells are similar with lack of internal structure
lack defiend nucleus - prokaryotic cells
what do eukaryotic cells contain
- membrane enclosed nuclei
- mitochondria and endoplasmic reticulum golgi apparatus chloroplasts
- evolved from common ancestor of archaea
- likely caused from relationship between archaea ancestors and bacteria
- protists, algae, slime, molds water molds and fungi
what was the ealiest microscope able to see
single celled organisms
what created the earliest microscop
Antony Van Leeuwenhoek
- not a trained scientist and took the world a long time to take him seriously
what were two major milestones in microbiology
- the development of a systematic set of proofs for determining whether a specific organism was responsible for specific disease - robert koch
- development of a series of effective vaccines - Louis pateur
what did the need to obtain pure culture do for microbiology
development of newer and more refined media growth tequnics
what did louis Pasteur do
- disproved spontaneous generation
- created succeful anthrax vaccine
- described chirality of chemical bonds
- developed pasteurization to preserve french wine
- developed germ theory
- developed attenuated
- developed vaccine for rabies
what is the light microscope
- the first created
- utilize lenses to bend light beams and focus and magnify samples
- different lenses will have different focuses and magnifications
- general sizes - 10x 40x and 100x
what are bright field microscopes
most common light microscopes
- source of light shines through the bottom through the sample and image is visible by contrast background
what is resolution
the ability to distinguish a point from a neightbourhouring point
- poor resolution means that objects bluur together
- for light miscroscopes the resolution is indicatied wavelength of light
- 0.2 um
what is contrast
- distinguishing the object from surrounding ones
- treat the sample with a stain or combination of stains
- the stain needs to be able to bind to specific parts of the sample to make it stand out
- one downside is it often kills the sample being stained
what is dark feild microscopy
imaging on a dark feild microscope
- dark background
- light is shinning on the sample instead of up through the sample
what is phase contrast microscopy
light passes through a living cell but will be slightly delayed
- amplifies small differenced so that light passing through an object will not cancel out light that didnt pass through
what is differential interference contrast microscope
uses differences in refractice indices and thickness of different parts of specimen to create an image
- use two beamd with right angeled lights
- one light passes through specimen while the other passes through delayed
- goes through prism to create three d object
flourescent microscopes
- some materials can absorb energy from one source and become excited and emit light
- illuminate the object with defined wavelength light beam
- flourescent dyes excite sample and they emit their own colour
confocal microscopy
creates shape 3d images
computer collects image data
scanning laser produces an image
- creates a series of flat images and stacks them to create 3d object
fixation and staining
- often stuck on glass slides to allow flooding and washing steps
- heat and chemical fixation are most common
- heat dries the sugars and sticks cells to glass
- chemicals imobolize samples (fermaldehyde)
staining has two dyes
basics - positively charged groups - bind to negatives
acidic dyes - negatively charged sticks to positive groups
what is the most used stain
gram stain
- used to differentiate gram positive and gram negative
electronic microscopes
beams of electrons are used instead of light beams
- electrons travel in waves
- wavelength is shorter than visible light
- 1000x better than light
-
transmission electron microscopes
shoot beams through the sample and image is viewed by its ability to block out electrons, much like bright feild light microscopes
staining in electron microscopes
- uses heavy metals because they are sufficient at blocking electrons and are often sprayed into other sampled to show them better
what are potential draw backs of electron microscopy
samples must be viewed in a vaccum as electrons do not travel through air
so the samples need to be dehydrated
-
scanning electron microscopy
electrons are bounced off at an angle
the electron beams scans focuse on beams of electrons along the samples and image is generated
scanning probe microscopy
- small prob scans along the surface of the sample specimen
- the prob is designed to move up or down in response to the contours or other properties on the surface
- scans to create a contour map = atomic force microscope
- does not require dehydrated samples or use of high vaccuum environement
