Unit 1
Define bioremediation
Uses microorganisms to break down or remove environmental pollutants, such as oil spills, pesticides, or toxic waste.
These microbial proteins bind to specific receptors on host cells to allow attachment
Adhesins
What is the difference between a spirillum and a spirochete?
Spirillum: thick rigid spiral
Spirochete: thin flexible spiral
Eukaryotic flagella and cilia have this microtubule arrangement.
9+2 arrangement
This technique uses an inoculating loop to separate individual cells on an agar plate.
Dilution streaking (streak plate method)
What was the main goal of Louis Pasteur's swan-neck flask expirement?
To disprove spontaneous generation by showing that microorganisms come from pre-existing microbes in the environment, not from nonliving matter. Air could enter the flask, but microbes were trapped in the curved neck, so no growth occurred unless contamination happened.
What is the difference between a biological and mechanical vector?
Biological vector: living organisms that transmit to humans (ex: mosquitos transmitting malaria)
Mechanical vector: physically carries the pathogen without biological development (ex: flies carrying bacteria on their legs)
This interaction of light is especially important in dark-field microscopy
Scattering of light
This type of movement allows spirochetes to move through viscous environments.
Corkscrew motility
This type of medium allows bacterial movement and observation of growth rate changes.
Liquid media
What is the Germ Theory of Disease, and which scientists confirmed it?
The Germ Theory of Disease states that specific microorganisms cause specific diseases.
Supported and confirmed by Louis Pasteur and Robert Koch
After an acute infection, this type of infection remains in the body without symptoms, such as herpes, causing cold sores.
Latent infection
Total magnification is calculated using this formula.
Total magnification = ocular lens x objective lens
How do eukaryotic flagella move in comparison to prokaryotic flagella?
Eukaryotic: ATP, whip-like
Prokaryotic: uses proton motive force, rotation
Media designed for organisms with demanding nutritional requirements are called this.
Enriched media
Binomial nomenclature
Genus + species
Genus: capitalized
species: lowercase
both: italicized
Define LD₅₀ and ID₅₀.
LD₅₀ (Lethal Dose 50%): the amount of a pathogen or toxin that kills 50% of a test population
ID₅₀ (Infectious Dose 50%): the number of organisms required to infect 50% of a test population
There are 2 types of these microscopes, one provides a 3D image of the surface of a specimen, and the other shows internal cell structures using thin sections of a specimen.
Electron microscopes
SEM (Scanning Electron Microscope) = 3D image of surface
TEM (Transmission Electron Microscope) = internal cell structures using thin sections
Where is ATP synthase located in the prokaryotic cell in comparison to the eukaryotic cell?
Prokaryotic: ATP synthase located in the plasma membrane
Eukaryotic: ATP synthase located in the inner mitochondrial membrane
Name the difference between auxotrophs and fastidious organisms.
Auxotroph: an organism that has lost the ability to synthesize a particular amino acid and will be unable to survive unless you supplement its media with the amino acid.
Fastidious: Organisms that are difficult to grow in a laboratory setting because they have complex and highly specific nutritional requirements.
What are the three functions of microbes?
1) Fix nitrogen into forms used by plants (nitrogen fixation)
2) Produce vitamins
3) Act as primary producers
Name the stages of infectious disease, and at what stage are symptoms most severe?
1) Incubation
2) Prodromal
3) Illness
4) Decline
5) Convalescence
Illness stage is when symptoms are most severe!
Differentiate between acid-fast staining, endospore staining, and acidic dyes
Acid-fast stain: identifies mycobacteria; cells retain primary stain after acid-alcohol decolorization, uses carbolfuchsin (acid-fast) and methylene blue (non-acid-fast)
Endospore stain: stains endospores (e.g., Bacillus, Clostridium) differently from vegetative cells, Malachite green (endospores) and Safranin (red/pink)
Acidic dyes: stain the background, leaving cells clear; useful for visualizing capsules
What are the components outside the cell wall, and describe each of them.
1) Capsules: well-organized layers made of polysaccharides that are covalently bonded and difficult to wash away.
2) Slime layers: Polysaccharide layers that are unorganized and easily washed away.
3) Glycocalyx: Polysaccharide extension that aids in attachment to solid surfaces.
4) S-layers: Geometric pattern made of protein that aids in protecting from ion and pH fluctuations.
Name the stages of bacterial growth and describe each stage.
Lag phase- cells adapt to the environment; little to no cell division
Log phase: rapid cell division at a constant rate
Stationary phase- growth rate equals death rate; nutrients are limited, and waste accumulates
Death phase-cells die faster than they divide