Lecuter 1 Flashcards
What is a microbe? Exceptions?
Organism too small to be seen by the unaided eye. Exceptions?
What does microbiology study
Study of microbes: prokaryotic, eukaryotic, acellular
How many microbes are estimated?
> 10^30 on the planet
What are the 3 domains of life?
Archaea, Bacteria and Eukarya
Explain the different arrangements of Cocci?
Coccus, diplococci, staphylococci, streptococci, sarcina, tetrad
Different arrangements of bacteria
- Rod-shaped (bacilli)
- Spherical (cocci)
- Spiral
Different bacteria have different morphologies, color T or F
T
What is a heterocyst
Different shapes of cells, specialized structures called heterocyst (H). A heterocyst is a differentiated cyanobacterial cell that carries out nitrogen fixation
Similarities and differences between Eubacteria and Archaebacteria?
Both:
- Prokaryotic
- No nucleus
- Single-celled
- Ribosomes
- No membrane-bound organelles
Eubacteria:
- Peptidoglycan in cell walls
- Cannot survive in extreme environments
- Bacteria and cyanobacteria
Archaebacteria:
- No peptidoglycan in cell walls
- Live in extreme envrionments
- Thermophiles, halophiles, methanogens
Eukaryotic microbes. Explain their cellular nature: protozoa, unicellular algae, fungi?
- Protozoa: no cell wall
- Unicellullar algae: cell wall, energy from sunlight
- Fungi: cell, wall, energy from organic materials
+ Moulds: generally filamentous
+ yeats: generally unicellular
Most fungi are dimorphic: have more than 1 form: yeast, filamentous or mushroom (fruiting body)
Concept of microbial communities
Microbes do not grow individually, they form communities
What are biofilms? How does it affect your body>
Biofilms are a slimy layer of microrganisms that adhere to sticky surfaces. Once the biofilm reaches the blood stream, they can spread to any moist surface of the human body
What are some properties of all living microbes, all cells
- Compartmentalization and metabolism.
- A cell is a compartment and takes up nutrients from the envrionemtn and transforms them, releases waste into the envrionment. the cell is thus an open system.
- Growth: chemicals from the environemnt are turned into new cells under the genetic direction of preexisiting cells
- Evolution: cells contain genes and evlove to display new biological preoprites
What are some properties of some cells
- Motility
Some cells are capable of self-propulsion - Differentiation
Some cells can form new structures such as a spore, usually as part of a cellular life cycle - Communication
Many cells communicate or interact by means of the chemicals that are released or taken up (biofims)
What are some catalytic and genetic functions of cells?
- Genetic functions: transcribe, DNA, replicatio, make proteins
- Catalytic functions:
+ Energy conservation: ADP + Pi -> ATP
+ Metabolism: generation of precursors of macro-molecules (sugars, amino acids, fatty acids,…)
+ Enzymes: metabolic catalysts
The closest relatives of eukaryotes among the prokaryotes are the
Archaea
Role of bacteria in nutrient cycling
- Recylce and transform nutrients: make nutrients available to other organisms
- bacteria are primary decomposers
- Important in numerous cycles:
+ carbon cycle: decompose when species die
Function of microorgansms in the nitrogen cycle
transfer of nitrogen in gas -> nitrogen thats usable for plants. Plants require nitrogen to grow. If you grow something on a certain soil for a long time -> supplemtn w nitrogen or else the plant cannot survive
Function of microorganisms in Sulphur
Sulphur is released from rocks through weathering and assimiltaed by microbes and plants
Microorganisms in bioremediation
Can break down oil, dry cleaning, pollutants, sewage, and can convert it to Co2 and H2o
Relationship between bacteria and plant in wastewater treatment
Plants provide habitat and nutrition to bacteria
while microbes:
- from biofilms
- degrade pollutants
- improve plant health
- denitrification
How many bacteria are there in your body> What functions do they have? Is everyone’s gut biome different? rely on waht?
Approx equal number of bacterial cells to human cells
- walking petri dish
- key functions in digestion and immune system
- symbiotic organism: relying on one another
how does microbiome in your body change over age
increases as you get older (expose to more)
decrease when you are old
Who developed the microsocope?
Antony Van Leeuwenhoek
he discovered “aminalcules”
What were the 2 controversities in the late 1600s?
- Spontaenous generation: is there formation of living orgnaisms from non-living materials>
- What is the true cause of a ‘contagious (infectious, transmissible” disease? - cause by microorganisms
What is Lazzaro Spallanzani experiment?
2 flasks, 1 with lid open, 1 with lid closed. both boiled. after the 1 was left open -> became turbid. the 2nd was closed>
How was the prescnece of microbes in Lazzaro Spallanzani’s experiment determined?
- tuburdity of previously clear broth: observed tuburdity in unboiled flask
- Decomposition of broth (smells): unboiled flask smelled
- Examination with microscope: organisms present in unboiled flask
For most bacteria, a minimum cell density of _____ cells is needed to see turbidity
10^7
Growth of microbes is an increase in the number of microbes rather than»
increase in the size of an individual microbe
What conclusions can be made from Spallanzani’s experiments?
- Microbial cells seen in the unboiled broth arose from pre-exisitng cells in the broth, not due to spontaneous generation of living cells from non-living broth
- If selaed flasks were opened to the air after boiling -> microbial growth occured. => air contained microbes
What applications of Spallanzani’s experiments?
-> concept: diseases were spread by microbes in the air
-> lead to new method of food preservation: canning.
Significancee: the ability to preserve food allowed increase exploration and migration of people and armies
What was Schroeder and von Fusch’s experiments? Observations?
Similar to Spallanzani, but inserted cotton plugs so filtered air could enter the flasks.
Observations:
- in unplugged flasks, microbial growth occured whether the broth had been boiled or not
- IN plugged flaskes, microbial growth occured only in the broth that had not been boiled
What conclusions can be made from Schroeder and von Dusch’s expeirments?
- Microbial growth requires the presence of pre-exisitng cells: there is no spontaneous generation
- Microbes in the air can be filtered out simply
What applications can be made from Schroeder and von Dusch’s expeirments?
- Filtration can remove microbes from liquids and air
- filter with 0.2 um pore size can remove most bacterial cells from soltions (but not most viruses)
- Use of HEPA filters (removes 0.2 um pariticles), not all viruses are removed since they are under 0.1 um
- Cotton plug: can be used in microbiology lab to protect sterile media
Concept of a Vaccine, how did Louis Pasteur come to this
From studies on disease on wine, and stuides on silkworm diseases -> lead to concepts and methods central to microbiology.
like rabies vaccine, and anthrax vaccine.
- Vaccine: is a preparation of either killed or weakened microorganism. Vaccines are used to induce an immune response in an aminal that will protec thte animal from the type of microganism/otoxin
Some of Louis Pasteur’s achievement
- Confiemd that the air is filled with microbes
- Microbial growth only occured when a nutrient source came in contact with existing microbes: not the result of spontaneous generation
- microbes could be transmitted though air: this could be the one rought by which contagious diseases might spread
Explain Pasteur’s expeirment with the Swan-necked flask:
After flask is boiled.
If flask remains upright, no microbial growth.
If flask tips, microorganism is trapped in the neck -< if reches the sterile liquid -> it can growh
What other achievments of Louis Pasteur?
Developed specific methods for removing all organisms (sterilization)
- removing target organisms (pasteurization)
- Aspetic and pure culture techniques to study pathogens
Along with Rober Koch -> usher the age of the “microbe hunters”
What is sterilization? What is a sterile material?
- Sterilization is the removal of all living organisms
- A sterile material contains no living organisms
What are the methods of sterilization
- Filtration
- Exposure to heat, ozone, ratdiaton, halogens
What is autoclaving?
Hot, saturated steam under pressure
121 degrees, pressure of 15 lbs/sq inch
- under these conditions, most cells spores and viruses would be kiled in 15 min
- the length of time for sterilzization depends on the volume of the material being autoclaved
What is pasteurization? how it works
Its the removal of specific unwanted target organisms, but not necessary the removal of all organisms.
Target organisms cause disease and/or rapid spoliage of the product.
The conditions of pasteurization depend on the target organism/substangce.
Its designed so the substance is not damanged.
For example: spolage of wine can be reudced by briefly heating at a certain temperature -> higher temperature would destroy the flavor of product
Development of pasteurization?
Wine was the first foodstuff to be pasteurized. MIlk and beer was next
The specific temperatire and times used for pasteurziation depndd on? Exmaple
The target organism/substance.
Raw milk contains beenficial bacteria and disease causing bacteria. Pastuerization is designed to inactivate the harmful orgnaisms, but not all
Different conditions of pastuerization
- Low temperature holding for long times
- high temperature short time
- ultra high temperature (givies extended shelf life, can be stored at RT)
- can also use filtrastion
Other methods of sterization
- Used when not possible/practical to expose a substance ot the conditions in autoclaving
- UV radiation at 160 um: for exposed surfaces such as tissue culture rooms
- ionizing radiation: deep penetration, sterilizing plastic ware, drugs, cosmetics
What is aseptic technique
Aspectic or sterile technique are specific method for handingling substnaces to maintan their sterility. Does not intrudce unwanted organisms (pure culture)
Difference between culture vs. Pure culture
Culture: growth of a desired type or types of organisms
pure culture: growth of only a single type of organism
How is a pure culture prepared?
- Removal of all organisms from culture medium by a method of sterilization
- Inoculation of the desired organism
- Incubation: proving conditions required for the growth of the desired organism
