Bio 3302 EXAM 2 STUDY GUIDE
Review Questions lab 11
1. What are the ingredients of starch agar?
Simple Nutritive medium with starch added
2. What is the function of lipases?
Too hydrolyze the triglyceride molecule into a glycerol molecule and three fatty acid chains
3. How is the ability of certain bacteria to attack phospholipids related to pathogenicity?
Since phospholipid are fatty acids, and cell membranes are made up phospholipids it can
breakdown down the cell membrane of cells and kill them
4. What is gelatin?
Is a protein derived from animal protein
5. What is unique about gelatin at 35°C versus 5°C?
At 35°C gelatin will be liquid and at 5°C gelatin will be solid
6. Why did you refrigerate the gelatin cultures before observing them for liquefaction?
To do Gelatin Liquification:
To see if the gelatin protein has been hydrolyzed. You freeze it, and if the tube turns back to
solid then gelatin is still there, if it stays liquid then gelatin has been hydrolyzed
7. Can gelatin hydrolysis be correlated with the pathogenicity of a bacterium? Explain your
answer.
Yes, some tissues are made up of collagen and if bacteria can hydrolyze collagen then our
tissues would be damaged
8. Read and analyze the starch, DNA, and gelatin tests.
Methyl green is a cation which binds to the negatively-charged DNA
When the DNA is broken down, it no longer binds to the methyl green, and a clear halo will
appear around the areas where the DNase-producing organism has grown.
Review Questions lab 12
1. What is the purpose of the phenol red in the fermentation tube? And what is the color of
phenol red at an acid pH?
, Bio 3302 EXAM 2 STUDY GUIDE
The phenol red is a ph indicator, turns yellow if acidic ph
2. What is the function of the Durham tube in the fermentation tube?
The Durham tube is used to catch the gas the fermentation produced. Durham tube will be
displaced
3. For what bacteria would you use the TSI test?
I
Identification of Enterobacteriacea FROM OTHER Gram-negative intestinal bacteria. by their
ability to catabolize glucose, lactose, or sucrose, and to liberate sulfides from ferrous
ammonium sulfate or sodium thiosulfate.
4. Distinguish between an acid and alkaline slant.
5. What is the purpose of thiosulfate in the TSI agar?
Sulfur sources or electron acceptors
6. What is the pH indicator in TSI agar?
Phenol read
7. Read and analyze the phenol red broth AND TSI
results Review Questions lab 13
1. What IMViC stand for?
IMViC test (indole, methyl red, Voges-Proskauer, and citrate)
2. Why did you shake the MR-VP culture?
3. What MR broth is used for?
To distinguish two different enterobacteria (glucose consuming) E coli: lactic acid, formic acids
and E. aerogenes; works for (butanol fermenter.)
4. What PV broth is used for?
identifies bacteria that ferment glucose. Will display a buetnol acculmulation
5. What test is indole used for?
To test whether a bacteria has the enzyme tryptophanase that hydrolyzes tryptophan, if indole
remains then the with the addition of kovacs agent the indole will till red
Review Questions lab 11
1. What are the ingredients of starch agar?
Simple Nutritive medium with starch added
2. What is the function of lipases?
Too hydrolyze the triglyceride molecule into a glycerol molecule and three fatty acid chains
3. How is the ability of certain bacteria to attack phospholipids related to pathogenicity?
Since phospholipid are fatty acids, and cell membranes are made up phospholipids it can
breakdown down the cell membrane of cells and kill them
4. What is gelatin?
Is a protein derived from animal protein
5. What is unique about gelatin at 35°C versus 5°C?
At 35°C gelatin will be liquid and at 5°C gelatin will be solid
6. Why did you refrigerate the gelatin cultures before observing them for liquefaction?
To do Gelatin Liquification:
To see if the gelatin protein has been hydrolyzed. You freeze it, and if the tube turns back to
solid then gelatin is still there, if it stays liquid then gelatin has been hydrolyzed
7. Can gelatin hydrolysis be correlated with the pathogenicity of a bacterium? Explain your
answer.
Yes, some tissues are made up of collagen and if bacteria can hydrolyze collagen then our
tissues would be damaged
8. Read and analyze the starch, DNA, and gelatin tests.
Methyl green is a cation which binds to the negatively-charged DNA
When the DNA is broken down, it no longer binds to the methyl green, and a clear halo will
appear around the areas where the DNase-producing organism has grown.
Review Questions lab 12
1. What is the purpose of the phenol red in the fermentation tube? And what is the color of
phenol red at an acid pH?
, Bio 3302 EXAM 2 STUDY GUIDE
The phenol red is a ph indicator, turns yellow if acidic ph
2. What is the function of the Durham tube in the fermentation tube?
The Durham tube is used to catch the gas the fermentation produced. Durham tube will be
displaced
3. For what bacteria would you use the TSI test?
I
Identification of Enterobacteriacea FROM OTHER Gram-negative intestinal bacteria. by their
ability to catabolize glucose, lactose, or sucrose, and to liberate sulfides from ferrous
ammonium sulfate or sodium thiosulfate.
4. Distinguish between an acid and alkaline slant.
5. What is the purpose of thiosulfate in the TSI agar?
Sulfur sources or electron acceptors
6. What is the pH indicator in TSI agar?
Phenol read
7. Read and analyze the phenol red broth AND TSI
results Review Questions lab 13
1. What IMViC stand for?
IMViC test (indole, methyl red, Voges-Proskauer, and citrate)
2. Why did you shake the MR-VP culture?
3. What MR broth is used for?
To distinguish two different enterobacteria (glucose consuming) E coli: lactic acid, formic acids
and E. aerogenes; works for (butanol fermenter.)
4. What PV broth is used for?
identifies bacteria that ferment glucose. Will display a buetnol acculmulation
5. What test is indole used for?
To test whether a bacteria has the enzyme tryptophanase that hydrolyzes tryptophan, if indole
remains then the with the addition of kovacs agent the indole will till red
