Lab Exam 2 Flashcards
What does pH measure?
How acidic or basic a solution is based on how many hydrogen ions the solution contains
Acidophilus
Microbes that grow well at or below pH 5.5
Neutrophiles
Organisms that grow well between 5.5 and 8.5
What group do most human pathogens fall into? Why?
Neutrophiles because the human body has a pH between 7.2-7.4
Alkalophiles
Organisms that live above pH 8.5
Why do medical laboratory facilities use media that contains buffers?
since the end product of many types of metabolism are acidic, this allows the pH of the media to stay stable as the microorganisms grow and divide
What is an example of common buffer systems that can alternate between weak acids and their conjugate bases?
Phosphate systems and bicarbonate systems
What are the biggest factors effecting which group the bacteria fall in?
1) Can they do respiration?
2) can they do an anaerobic method of energy production like anaerobic respiration and fermentation?
3) does the bacteria have the enzymes like catalase or superoxide dismutase to handle/breakdown O2, and its toxic derivatives?
What are the oxygen conditions and bacterial growth for Obligate Aerobes?
O2 requirements: Needs
Metabolism Type: Aerobic Respiration
Enzymes to handle reactive oxygen: Yes
What are the oxygen conditions and bacterial growth for Microaerophiles?
O2 requirements: Needs low level
Metabolism Type: Aerobic Respiration
Enzymes to handle reactive oxygen: Yes, but low level, can be damaged by high O2
What are the oxygen conditions and bacterial growth for Faculative anaerobes?
O2 requirements: Grows better with O2, can grow without O2
Metabolism Type: Aerobic respiration, anaerobic respiration
Enzymes to handle reactive oxygen: Yes
What are the oxygen conditions and bacterial growth for aerotolerant anaerobes?
O2 requirements: None, O2 can be present
Metabolism Type: Anaerobic method
Enzymes to handle reactive oxygen: Yes
What are the oxygen conditions and bacterial growth of strict anaerobes?
O2 requirements: none! O2 is toxic
Metabolism Type: anaerobic method
Enzymes to handle reactive oxygen: no
What is a nonselective enriched media that can grow a wide array of microorganisms?
Thioglycollate broth
Media components of thioglycollate broth
1) Yeast extract, digested casein= nutrients for growth
2) Sodium thioglycolate and L-cystine= lowers the amount of oxygen in the media
3) Resazurin= color indicator that is pink when oxidized and colorless when reduced, so it shows there is oxygen when pink. The tube you get should be slightly pink at the top, indicating there is an oxygen gradient going down the media
What happens if it is too cold for an enzyme?
It will slow down the rate of chemical reactions
Psychrophiles temperature
Minimum C: -10
Optimum C: 15
Maximum C: 20
Psychrotrophs temperature
Minimum C: 0
Optimum C: 20
Maximum C: 35
Mesophpiles temperature
Minimum C: 15
Optimum C: 20-45 range
Maximum C: 45
Thermophiles temperature
Minimum C: 45
Optimum C: 55-65 range
Maximum C: 85
Extreme Thermophiles temperature
Minimum C: 55
Optimum C: 85-113 range
Maximum C: 113
What is transformation used to describe?
When a microorganism can uptake DNA from its environment
What is one mechanism by which bacteria do horizontal gene transfer?
Transformation
Are every species of bacteria capable of doing the process of transformation?
NO
What do you call cells that are capable of undergoing transformation?
Competent Cells
What is an example of cells that do not normally do transformation?
Eukaryotic cells
The most successful stable transformations involve genes that are coded for on a ______ because circular DNA is less likely to be degraded
Plasmid
What is a plasmid?
A small piece of double stranded DNA that can autonomously replicate independent of the host chromosome1
What is an Operon?
A group of features coded for within the DNA and is a functional genetic unit in a prokaryote
What are the parts of the arabinose operon?
the promoter and the araC gene
What is a promoter?
The DNA sequence/region where the RNA polymerase binds
Possible outcomes for genetic engineering when cloning a gene:
This is the outcome:
Transformation did not take place
What would a plate containing ampicillin look like?
No growth on the plate
Possible outcomes for genetic engineering when cloning a gene:
This is the outcome:
Transformation did take place, but insertion of the gene into the multiple cloning site situated in the middle of the “color indicator” gene was faulty
What would a plate containing ampicillin look like?
Growth will take place on the plate, and the colonies will have color/fluoresce
Possible outcomes for genetic engineering when cloning a gene:
This is the outcome:
Transformation did take place, AND gene successfully inserted into the middle of the “color indicator” gene
What would a plate containing ampicillin look like?
Growth will take place on the plate, but they will be white/cream colored and not fluoresce as the gene that produces color was interrupted
Cardinal Temperature for Thermophiles
Adapted to temperature greater than 45 degrees C
Cardinal temperature of Obligate Thermophiles
Will not grow at a temperature less than 40 degrees C
Cardinal temperature of Faculative Thermophiles
Will grow below 40 degrees C
Cardinal temperature of Extreme Thermophiles
Grow best above 80 Degrees C
How does the internal environment of bacteria change based on their external environment conditions?
Regardless of their habitat, bacteria maintain a near-neutral internal environment
Why are buffers added to growth media?
To maintain equilibrium
Where will an obligate aerobe grow in a fluid thioglycollate medium?
Will grow at the top of the media where oxygen is most plentiful
Where will facultative anaerobes grow in a fluid thioglycollate medium?
Will grow throughout the medium but will appear denser at the top
Where will an obligate anaerobe grow in a fluid thioglycollate medium?
Will only grow in the lower regions of the medium (least amount of oxygen)
Where will aerotolerants grow in a fluid thioglycollate medium?
Will grow uniformly throughout the medium
(EMB plate)
Selective and differential mediums have what effect on gram + organisms?
They inhibit their growth
(EMB plate)
In a Selective and differential medium, what is the enteric based on fermentation for Non-lactose fermenters?
Normal colored colonies
(EMB plate)
In a Selective and differential medium, what is the enteric based on fermentation for Vigorous lactose fermenters?
Dark purple to black colonies
(EMB plate)
In a Selective and differential medium, what is the enteric based on fermentation for less aggressive lactose fermenters?
Pink to dark purple colonies
What does E. coli look on an EMB plate?
Dark colonies with metallic green sheen
What does Enterobacter/Klebsiella look like on an EMB plate?
Pink to dark purple colonies
(HEA plate)
How does the selective and differential medium affect the growth of gram + organisms?
It inhibits the growth
(HEA Plate)
What color do enterics that ferment 1 or more carbohydrate turn?
Yellow or salmon colored
What is an HEA plate designed to do?
Isolate salmonella and shigella from other enterics
What color is Salmonella on a HEA plate?
Black colonies
What color is Shigella on a HEA plate?
Green colonies
What color is categorized as other coliforms on an HEA plate?
Yellow or salmon colored colonies
What is araC?
A binding protein that attaches to the promoter and functions as an on/off switch
What are the parts of the arabinose operon?
- Promotor (Pbad)
- Three structural genes (araB, araA, and araD)
- code for enzymes used to digest arabinose
- araC
Bacteriophage Tr4 and ΦX174 infect what?
E. coli
What is Tr4?
A Double stranded DNA phage
What is ΦX174?
A Single stranded DNA phage
What is one of the largest phages and can only undergo a lytic lifestyle?
Tr4
What is it called when you compare the bacteriophage sensitivities?
Phage typing
What is Bioremediation?
The process of using living organisms to clean up pollution in the environment
What color does the presence of Pseudomonas fluorescens turn the indicator? why?
It turns it pink because the byproducts from the reduction of the oil’s carbon compounds reduce the tetrazolium
Why is type O the universal donor?
Because there are no antigens that can be recognized by the recipient
Why is AB the universal recipient?
Because they have no Abs in their serum
Transfusion of blood into a recipient possessing antibodies to one of the donor blood group antigens can result in a…
Transfusion reaction
High levels of what may be toxic to the Kidneys causing acute tubular cell necrosis and renal failure?
Hemoglobin
Epidemiology
The study of infectious diseases and non-infectious diseases
What falls under the category of epidemiology?
Studying the cause of the disease, the prevalence of the disease, and the transmission of disease
What is it called when a disease is transferred from animals to humans?
A zoonotic disease
What are the routes of transfer of a diesease?
1) inhalation of airborne microbe via droplets nuclei
2) ingestion of contaminated food or water
3) through the bite of an animal
4) direct contact through sexual contact
5) through blood or tissue as in blood transfusion or transplants
6) by the bite of an insect- a vector organism like a tick
7) transfer via an inanimate object (fomite), like your phone or a door knob
what does K represent in the prevalence rate and incidence rate equations?
The number of people
Point Prevalence equation
Point Prevalence = [ number of existing cases at point to time/size of at risk population] * K
Incidence Rate equation
Incidence rate = [ number of new cases in a time period/size of at-risk population at midpoint of time period]*K
What are the largest majority of microbes found in the soil?
Saprophytes
What are Saprophytes?
Beneficial microorganisms that can break down organic matter to enrich the soil
What are some reasons to test the soil?
- To test for fungal plant pathogens
- Health officials might want to know if there is contamination of an area by fecal bacteria or human pathogenic bacteria
What is used to grow Actinomycetes bacteria?
Glucose Yeast Extract Agar (GYE agar)
What is a genera non-selective type of media that can grow a wide variety of microorganisms?
Tryptic (Trypticase) Soy Agar (TSA)
An agar used to grow fungi
Sabouraud Dextrose Agar (SDA)
What is the second leading cause of death for children under the age of 5
diarrheal disease
What are coliforms?
Rod-shaped gram-negative, non sore forming and motile or non motile bacteria that can ferment lactose with the production of acid and gas when incubated at 35-37 degrees C
What are coliforms that live in the digestive tracts of animals?
Fecal coliforms
What does the most probable number (MPN) test determine?
The number of total coliforms in a water sample
What are the three parts an MPN test is divided into?
Presumptive, confirmed, and completed tests
what type of bacteria is a lactose tryptose broth selective for due to the presence of lauryl sulfate?
Gram negative
The more diluted the sample, the likelihood of the broth being inoculated ___________, resulting in no growth
Decreases
The more ______ the sample, the less likely you are to have gas production from that subset of microorganisms
Dilute
Why do we need to be able to test how sensitive a strain of bacteria is to a particular antibiotic?
Because not all antibiotics naturally work against all types of bacterial infections
Are gram positive or gram negative bacteria harder to kill? Why?
Gram negative because of their outer membrane
What is the Kirby-Bauer disk diffusion method?
Spread bacteria on an agar plate to grow a lawn and put an antibiotic-infused disk in the center
Bacteriostatic definition
Inhibition of growth
A substance that prevents the multiplying of bacteria without destroying them
Bactericide definition
A substance which kills bacteria
What are the clear rings around a Kirby-Bauer disk called?
Zones of inhibition
What kind of agar is used for a Kirby-Bauer test?
Mueller-Hinton agar
