Micro exam II Flashcards
The process in which all living cell and non-living disease agents (spores, viruses, etc.) are eradicated from an object or a place
sterilization
The removal or inhibition of disease-causing microbes from an object or place
disinfection
The process in which microbial levels are reduced to non-hazardous levels as defined by public health board
sanitization
A chemical that wipes out all living cells and non-living disease agents
sterilant
An agent that wipes out most microbes (never spores and some resistant microbes do existant)
disinfectant
An agent that doesn’t kill all cells. It is used to prevent infection or sepsis of a living tissue by microbes.
antiseptic
Compounds that are made by microbes to kill bacterial competitors. They are selectively toxic to prokaryotic cells and have no effect on non-cellular disease-causing agents (viruses)
antibiotics
Any antifungal agent
antimycotic
An agent that selectively disrupts viral DNA replication more than it disrupts eukaryotic DNA replication
Antiviral
what does the suffix “-cide” mean in terms of antimicrobial agents
kills bacteria, but the cells remain intact
what does the suffic “-lytic” mean in terms of antimicrobial agents?
Kills bacteria by lysis fo the cells
What does the suffix “-static” mean in terms of antimicrobial agents
suspends growth of cells, leaving them intact. Once the agent is removed, cells will begin to grow again.
What are the seven environmental factors that affect attempts to control microbial growth?
- Size of the population
- Composition of the population
- Concentration of the antimicrobial agent used
- Length of exposure to antimicrobial agent
- Temperature
- Composition of the local environment
- Type of microbe
How does the chemical control method phenolics work?
- denature proteins in microbes
- disrupt cell membranes
The microbial growth curve phase in which the inoculum has occurred and there is no increase in the amount of bacterial cells. Cells are growing larger and are metabolically active
Lag phase
The microbial growth phase in which cells are actively dividing by binary fission and their numbers are increasing exponentially
log phase
The microbial growth curve phase in which the number of new cells created by cell division is equal to the number of cells dying. Cells are dying due to waste product accumulation and nutrients being used up. The gradual depletion of oxygen begins to limit cell growth.
Stationary phase
The microbial growth curve phase in which more cells are dying than cells that are being produced. Viable count decreases exponentially
death or decline phase
Direct count
a method of counting cells that counts individual cells by looking at them under a microscope or by counting colonies on a plate
indirect count
a method of counting cells that depends on measurement of cell presence or activity without actually counting individual cells.
Viable count
The number of alive cells
Total count
the number of bacterial cells in a culture, both live and dead
An indirect method of counting cells that looks at how cloudy or turbid a sample is
Optical Density
The time it takes for the population to double through one round of binary fission
Generation time or doubling time
What mechanism is used by alcohols to disrupt microbial growth?
- Denatures proteins
- Destroys membranes by dissolving lipids
What mechanism is used by halogens to disrupt microbial growth?
- Oxidizes cell membranes and organelles
- Can halogenate proteins, making them inactive
What mechanism is used by heavy metals to disrupt microbial growth?
Denaturation of proteins by combining with sulfhydryl groups
What mechanism is used by quats (quaternary ammonium compounds) to disrupt microbial growth?
Each molecule has a polar and nonpolar region. Quats with long non-polar regions can disrupt plasma membranes (causing lysis)
What mechanism is used by aldehydes to disrupt microbial growth?
“fix” tissues and cells by denaturing membrane-bound and cytoplasmic proteins of the cell
what mechanism is used by gas sterilization to disrupt microbial growth?
denatures proteins in both spores and vegetative cells
What are fomites?
Inanimate object which carry germs/microbes from one place to another. Example: door knobs, toys, towels, toilet handle, used bandage, etc.
The BSL in which agents generally do not cause infections in healthy adults. non-pathogens such as E. coli and Bacillus subtilis
BSL-1
The BSL that works with pathogens, but are not airborne and are typically found in the area. Examples: S. aureus and Salmonella
BSL-2
BSL that are airborne pathogens and have the potentional to cause lethal infections by inhalation. Example: covid, measles, Bacillus anthracis
BSL-3
BSL in which pathogens that cause infections that aren’t treatable, are often fatal, and are usual transmitted in multiple ways. Example: ebola, smallpox, Marburg virus
BSL-4
What is thermal death time (TDT) and what is it used for?
The length of time needed to kill all microorganisms in a sample at a give temperature
What are the three domains of living organisms?
- Bacteria
- Archaea
- Eukarya
Which class of proteobacteria are oligotrophs (can live in an environment with very low nutrients?
alphaproteobacteria
What class of proteobacteria are eutrophs (organisms living in habitats that have high levels of nutrients)? Includes human pathogens of the genus Neissara and the species Bordetella pertussis
Betaproteobacteria
What class of proteobacteria is the largest and most diverse group? Many are human pathogens that are aerobes or facultative anaerobes. Some are enteric. example: E. coli
Gammaproteobacteria
What class of proteobacteria makes up a small group that is able to reduce sulfate or elemental sulfur?
Deltaproteobacteria
What class of proteobacteria makes up the smallest group of proteobacteria? Examples: Camplyobacter and Helicobacter
epsilonproteobacteria
What taxa do nonproteobacteria gram-negative bacteria include?
spirochetes
What are two examples of a spirochete and what diseases do they cause? Also, what prokaryotic group do they belong to?
- Trepnonema pallidum - syphilis
- Borrelia burgdorferi - Lyme disease
They belong to nonproteobacteria gram-negative bacteria
What are low G+C gram positive bacteria called? Give an example of one
Actinobacteria
examples: Mycobacterium tuberculosis, M. leprae, Corynebacterium diptheriae
What are high G+C gram negative bacteria called? Give an example of one
Bacilli
examples: B. anthracis, B. cereus, and S. aureus
What is meant by the term “deeply branching prokaryotes”? Can you name one?
- Have gene sequences that are found between LUCA and bacteria and archaea
- phylogenetically the most ancient forms of life
- example: Deinococcus radiodurans
What are some methods used for phenotypic analysis?
staining, observing colony morphology, size, color, biochemical properties
What processes have developed (over evolutionary time) to allow bacterial species to “compensate” for the disadvantages of asexual reproduction?
- Increase in mutation rate
- Horizontal gene transfers
- Transposons
HGT in which dead donor DNA is picked up from environment by a live recipient
Transformation
HGT in which 2 live cells are connected by a pilus
Conjugation
HGT in which DNA is carried by a 3rd party from donor to recipient
Transduction
Type of transduction carried out by a virulent phage - Can take any gene from a donor cell and transfer it to the recipient cell
General transduction
Type of transduction carried out by a temperate (lambda) phage - can incorporate donor chromosomal DNA into recipient genome.
Specialized transduction
What are 2 things that might prevent an HGT from increasing gen div within a population of bacteria?
- Restriction enzymes in recipient cytoplasm could chop up the transferred DNA
- If the pilus breaks, transfer of DNA is stopped
mobile segments of DNA that can move within the genome of an organism
Transposons
How do transposons help bacteria become more genetically diverse?
Because transposons can move within a DNA molecule, from one DNA molecule to another, or even from one cell to another, they have the ability to introduce genetic diversity:
1. Movement within the same DNA molecule can alter phenotype by inactivating or activating a gene
2. Transposons may carry additional genes with them, moving these genes from one location to another
Breaking bonds, oxidizing bonds,- ΔG (favorable), +ΔS (increase in entropy), loss of electrons (LeO)
catabolic
Make bonds, synthesis, +ΔG, -ΔS (less entropy), gain of electrons (GeR)
Anabolic
cells that have lost an ability that was the ability to make something
Anabolic auxotroph
cell from the original culture that was able to make something
anabolic prototroph
A type of organism that has lost an ability to break down a certain type of sugar that its parent was able to break down.
Catabolic auxotroph
A cell from the original culture that was able to break down a certain type of sugar
Catabolic prototroph
How would you select for a mutant that has LOST an ability that the “parent” culture had? For example, how would you find a Gal- mutant in a Gal+ culture of bacteria? Gal is for galactose, a type of sugar that some bacteria can eat.
- Apply a mutating factor (UV light) to a Gal+ culture
- Inoculate general media to allow growth of both Gal+ and Gal- bacteria
- Make a replica plate that is selective and includes Gal as the only carbon source. This will kill off all of the Gal- bacteria, and allow us to compare to the master plate to find where the Gal- colonies are located
What is the difference between direct and indirect selection?
direct: Selecting for a mutant that has GAINED and ability
indirect: selecting for a mutant that has LOST an ability
How would you select for a mutant that has LOST an ability that the “parent” culture had? For example, how would you find a Cys- mutant in a Cys+ culture of bacteria? Cys is for cysteine, an amino acid that some bacteria can make.
- expose a culture of Cys+ cells to UV light
- inoculate agar that is enriched with cysteine to allow growth of both Cys+ and Cys- colonies
- Make a replica plate that is selective and does not contain cysteine. Only Cys+ will grow.
- Compare replica plate to master plate. The colonies that didn’t grow on the replica plate are the Cys- colonies
How would you select for a mutant that has GAINED an ability that the “parent” culture did not possess? For example, how would you find a Bio+ mutant in a Bio- culture of bacteria? Biotin is a vitamin that some cells can make.
- expose a Bio- culture in TSB to UV light
- Inoculate medium that is selective and does not contain biotin.
- colonies that grow will be bio+
How would you select for a mutant that has GAINED an ability that the “parent” culture did not possess? For example, how would you find a Lac+ mutant in a Lac- culture of bacteria? Lactose is a sugar that some cells can eat.
- apply UV light to a culture of Lac+ cells in TSB
- inoculate media that is selective and contains lactose as the only carbon source
A direct selection method that uses bacteria to measure the mutation rate associated with exposure to a particular chemical compound. Food additives are tested using this method.
Ames test
The complete oxidation of an initial organic electron donor wherein the final electron acceptor is inorganic
Respiration
Why can we say that “a change in genotype always causes a change in phenotype” for bacteria? What molecular-level structures/factors cause this to be so?
Bacteria are haploid, so they only have one copy/one allele per gene because they reproduce asexually. Therefore, there are no dominant/recessive alleles. Whatever allele the cell has, they express.
The incomplete oxidation of an initial organic electron donor, wherein the final electron acceptor is organic
Fermentation
Give two example of a final e- acceptor and the final reduced product it turns into for an anaerobic respiration
- NO3- & NO2- produce nitrogen gas (N2)
- Sulfate —> H2S (TSIA slants)
Why can one compare fermentation to taking just the “first bite out of a cookie” and not eating the rest of it? What units are used to signify that energy is left behind in a fermentation product?
- Because it is incomplete; it leaves all of those carbon-carbon bonds in the rest of the cookie
- The units that are left behind are calories
What are the inputs/outputs of the Embden-Meyerhof-Parnas pathway (glycolisis)
- Starts with glucose
- Results in 2 pyruvate, 2 net ATP, 2 NADH
What are the inputs/outputs of the Entner-Dourderoff pathway? What are the benefits of this pathway as opposed to glycolysis?
- starts with glucose
- Results in 2 pyruvate, 1 NADH, 1 net ATP, 1 NADPH
- The NADPH helps to power biosynthesis reactions
What are the inputs/outputs of the phosphoketolase pathway? What are the tradeoffs opposed to glycolysis?
- starts with Glucose
- -1 ATP, 2 NADPH, 1 Ribose, 1 CO2
- Helps with nucleic acid synthesis/cell division
What are the inputs/outputs of the pentose phosphate shunt/pathway? What are the benefits to this pathway as opposed to glycolysis?
- Starts with glycolysis
- Results in 1 pyruvate, -1 NADH, 1 net ATP, 2 NADPH, 1 CO2, 1 ethanol
- Beneficial because the production of ethanol creates competition among surrounding bacteria.
