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