Lab Exam 1

1.       What is the purpose of streaking for isolation?

-          To dilute a bacterial sample to get isolated colonies

2.       What does Turbid mean?

-          Cloudy broth meaning bacteria had grown

3.       What is a Pellicle?

-          Bacteria growing on top of broth

4.       What is Sediment?

-          Bacteria growing on bottom of the broth

1.       What does facultative mean?

-          They can use to pathways

2.       How does fermentation start?

-          With the breakdown of the Carbon Source (Sugars)

3.       What are the results if you mix water and yeast?

-          No foaming meaning that fermentation did not occur

4.       What are the results if your mix water, yeast, and sugar?

-          Foam forms meaning that carbon dioxide was produced so fermentation occurred

5.       What are the end products of this reaction?

-          ATP, Carbon dioxide, and Ethanol

6.       If there was negative results why did fermentation not take place?

-          No carbon source

1.       Why do short wavelengths have a better resolution?

-          Able to fit between and around very small objects

2.       What is the purpose of Immersion Oil?

-          Eliminate bending of light as lights passes from the glass slide to the lens

3.       What is the total magnification of 4X, 10X, 40X, and 100X?

-          40X, 100X, 400X, 1000X

1.       What is Chromagen?

-          Colors a stain

2.       What is another word for Emulsions?

-          Smear

3.       What is the purpose of Heat fixing a smear?

-          Keep cells stuck on slide and to kill bacteria

1.       What is the differential step?

-          Decolorizer

2.       What color do gram negatives stain?

-          Pink

3.       What color do gram positives stain?

-          Purple

4.       What color will cell stain if you forget crystal violet?

-          Pink and it’s a false negative test

5.       What color will cell stain if you forget decolorizer?

-          Purple and it’s a false positive test

6.       What color will cell stain if you forget iodine?

-          Pink and it’s a false negative test

7.       What color will cell stain if you forget safranin?

-          Gram +: Purple and Gram –: Clear

1.       What is the purpose of Catalase?

-          Differentiate between gram positive bacteria

2.       What does it mean when we have a positive Catalase test?

-          Bubbles, has catalase, and likely not streptococcus or Enterococcus

3.       What does it mean when we have a negative Catalase Test?

-          No bubbles, does not contain catalase, and likely Streptococcus or Enterococcus

1.       What is the purpose of Coagulase?

-          Forms a fortress or agglutination protecting it from our immune system

2.       What are the results of a positive coagulase test?

-          Blue, agglutination, contains coagulase, and likely Staphylococcus Aureus

3.       What are the results of a negative coagulase test?

-          Purple, no agglutination, does not contain coagulase, and not likely Staphylococcus aureus

4.       Who is the trickster in a coagulase test?

-          Enterococcus faecalis

1.       What is the selective media in a MSA plate?

-          Salt

2.       What is the differential media in a MSA plate?

-          Mannitol

3.       What is the purpose of TSA plate?

-          To show growth of all bacteria and make sure they are alive

4.       What does it mean if there is growth on MSA plate?

-          Halotolerant

5.       What does it mean if there is no growth on MSA plate?

-          Not halotolerant

6.       What does it mean if there is a color change?

-          Can ferment mannitol

7.       What does it mean if there is no color change?

-          Cannot ferment mannitol

8.       What is does it mean if there is growth and yellow color change in MSA plate ?

-          Halotolerant, can ferment mannitol , likely Staphylococcus Aureus

9.       What does it mean if there is only growth in MSA plate?

-          Halotolerant, cannot ferment mannitol, likely Staphylococcus Epidermidis

10.   What does it mean no growth or color change in MSA plate?

-          Not halotolerant, cannot ferment mannitol, likely Streptococcus Pyogenes

11.   Who is the trickster in MSA test?

-          Enterococcus faecalis

What is the differential ingredient in blood agar plates

-          RBC

What is tested during a hemolysis test?

-          Toxin Hemolysins

What do Hemolysins do?

-          They destroyed not only RBC but WBC as well

What is gamma hemolysis?

-          No hemolysis

What is alpha hemolysis?

-          Incomplete hemolysis

What is bet hemolysis?

-          Complete hemolysis

What does the Beta hemolysis results tell you?

-          Clearing, likely strep pyogens or staph aureus

What does Gamma hemolysis results tell you?

No clearin, likely staph epiderm or entero faecalis

What is the purpose of esculinase ?

-          Used to identify enterococcus faecal

What is the purpose of Bile?

-          Inhibits the growth of most gram positive bacteria

What does a positive bile test mean?

-          Growth so it tolerates bile and darkening so it contains esculinase likely ef

What does a negative bile test mean?

-          No growth doesn’t tolerate bile no darkening so not esulinase likely not ef