Exam 2 Objectives Flashcards
What is osmotic pressure?
How badly water wants to leave a cell.
What does osmotic pressure depend on?
Depends on solute concentration of medium cell is in.
What is a hypotonic medium?
High solute concentration in cell, low out cell, cell could lyse open.
What is a hypertonic medium?
Low solute concentration in cell, high out cell, cell dehydrates (shrinks).
What are halophiles?
Grow best in high NaCl concentration.
What are osmophiles?
Adapted to environments with high osmotic pressure.
What is a psychrophile?
Grows best at less than 15 degrees Celcius.
What is a mesophile?
Grows best at 20-40 degrees Celcius.
What is a thermophile?
Grows best at more than 40 degrees Celcius.
What is in a thioglycolate tube that serves as an indicator?
Has a green later of methylene blue, which turns green in the presence of O2.
How do we innoculate a thioglycolate tube?
Innoculate like normal, but don’t disturb media too much.
What is an aerobe?
Needs O2 to survive; only growth in the green layer.
What is a faculatative anerobe?
Can live with or without O2, growth throughout the entire tube.
What is an anaerobe?
Does not need O2, growth in only bottom/yellow layer of the tube.
How do we innoculate a fermentation broth?
Innoculate the broth like normal.
What pH indicator is in the fermentation tubes?
Contains the pH indicator Bromocresolpurple, which turns yellow if pH drops.
What does it mean if the tube turns yellow?
Fermentation has occurred.
What is special about one of the oxidation/fermentation tubes?
One tube has a layer of oil on top to keep O2 out of the broth.
What pH indicator is in the oxidation/fermentation tubes?
They both contain the pH indicator bromothymol blue.
How do was innoculate the oxidation/fermentation tubes?
We innoculate it like normal.
What happens if both tubes turn yellow?
The bacteria are fermenters.
What happens if the non-oil turns yellow and the tube with oil turns green?
The bacteria performs oxidation.
What happens if both tubes are green?
Neither fermentation or oxidation took place.
What is a Durham tube?
A small, inverted test tube immersed in the broth.
What does a Durham tube do?
Added for the ease of seeing gas production.
How do we read a Durham tube?
If there is a small bubble in the tube, then gas was produced by the bacteria in the broth.
How do we innoculate a phenylalanine deaminase test?
Innoculate the slant like normal.
What do we add to the phenylalanine slant after incubation?
Add 5 to 10 drops of ferric chloride.
What happens if the phenylalanine slant remains yellow?
The bacteria does not produce the enzyme phenylalanine deaminase.
What happens if the phenylalanine slant turns green?
The bacteria does produce phenylalanine deaminase.
What does phenylalanine deaminase do?
Removes the amino group from the amino acid phenylalanine to produce phenyl pyruvic acid and ammonia.
How do we innoculate a nitrate broth tube?
Inoculate the broth like normal.
What do you add to the broth after incubation?
Nitrate A and Nitrate B.
What happens if a red color is observed after Nitrate A and B is added?
The bacteria is positive for nitrate reductase.
What happens if there is no color change observed after Nitrate A and B is added?
Add zinc powder to the tube.
What happens if no color change is observed after zinc powder is added?
The bacteria is positive for nitrate reductase.
What happens if a red color change is observed after zinc powder is added?
The bacteria is negative for nitrate reductase.
What does ferric acid do?
Binds to the phenyl pyruvic acid and the resulting complex is a green-colored compound.
What do nitrate A and B do?
React with nitrite to form a red dye.
What does zinc powder do?
Reduces nitrate to nitrite.
What is denitrification?
When an organism reduces nitrate (NO3) to nitrite (NO2), to nitric oxide (NO), to nitrous oxide (N2O), finally to dinitrogenous gas (N2).
How do we inoculate a casein test and what is a positive result?
Inoculate 4 quadrant streak plate
If positive, the area around the bacteria becomes clear.
How do we innoculate a gelatin test and what is a positive result?
Inoculate tube.
If positive, gelatin would be liquid at room temperature after being chilled.
How do we innoculate a starch test and what is a positive result?
Inoculate 4 quadrant streak plate
Flood with iodine after incubation
If positive, the area around the bacteria will be lighter, instead of dark brown.
How do we inoculate a lipid test and what is a positive result?
Inoculate a spirit-blue agar plate with a single line down the middle.
If positive, the area around the bacteria will be free of cloudiness (hold up to the light).
How do we inoculate a DNA test and what is a positive result?
Streak plate with the indicator toluidine blue in it.
If positive, there is a pink/purple color change observed.
What are the substrates and products in the casein plate?
The protein casein is broken down by the enzyme caseinase into shorter chains of amino acids.
What media was used in the casein plate?
Skim milk agar.
What are the substrates and products in the gelatin tube?
The protein gelatin is broken down by the enzyme gelatinase into shorter chains of amino acids.
What media was used in the gelatin tube?
Nutrient gelatin.
What are the substrates and products in the starch plate?
The carbohydrate starch is broken down by the enzyme alpha-amylase into dextrine (shorter chains of glucose).
What media was used in the starch plate?
Starch agar.
What are the substrates and products in the lipid plate?
Lipids are broken down by the enzyme lipase into glycerol and fatty acids.
What media was used in the lipid plate?
Spirit-blue agar.
What are the substrates and products in the DNA plate?
DNA is broken down by the enzyme DNase into nucleotides.
What media was used in the DNA plate?
DNase agar.
What is an antiseptic?
Antimicrobial used on a living surface.
What is a disinfectant?
Antimicrobial used on a non-living object.
How do you make a lawn of bacteria?
Dip a swab in broth.
Brush it over agar in 3 different directions.
How do we inoculate a disk diffusion test?
Make a lawn of bacteria.
Dip black paper disk in test agent, and stick it to the agar.
Why is ultraviolet light harmful to cells?
It causes thymine dimers.
What is a thymine dimer?
A pair of abnormally chemically bonded adjacent thymine bases in DNA, resulting from damage by ultra-violet radiation.
What does the killing power of UV light depend on?
Distance from the lamp.
Intensity of the UV light.
Time of exposure.
How did we test the killing power of UV light in lab?
We inoculated a plate, covered one side with a paper towel, then exposed it to radiation (UV) for different amounts of time.
What are the three ways moist heat can be used to kill microbes discussed in lab?
Boiling
Pasteurization
Autoclave
Which way of moist heat can sterilize things?
Autoclave-steam under pressure.
What are the two ways dry heat can be used to kill microbes discussed in lab?
Hot air oven
Incineration
What is the thermal death point of an organism?
The lowest temperature that kills at a given time (10 min).
What is the thermal death time of an organism?
The shortest time that kills at a given temperature.
What is the antibiotic P10 and how does it inhibit bacterial growth?
Penicillin - cell wall inhibitor
What is the antibiotic SXT and how does it inhibit bacterial growth?
Sulfa drug - folic acid production inhibitor
What is the antibiotic Te30 and how does it inhibit bacterial growth?
Tetracyclin - protein synthesis inhibitor.
What is the antibiotic B10 and how does it inhibit bacterial growth?
Bacitracin - cell wall inhibitor.
What media do we use to test the susceptibility of organisms to different antibiotics?
Mueller-Hinton agar.
How do we innoculate a test to test the susceptibility of organisms to different antibiotics?
Create a bacterial lawn.
Put antibiotic paper disks on agar.
Measure zone of inhibition.
