Lab Quiz #3

Question 1

Enzymes called decarboxylase catalyze the removal of the _____ from an amino acid

5-10 Decarboxylation Test

Answer 1

Carboxyl Group

5-10 Decarboxylation Test

Question 2

Enzymes called deaminase catalyze the removal of the ____ from an amino acid

5-10 Decarboxylation Test

Answer 2

Amine Group

5-10 Decarboxylation Test

Question 3

What is meant by the substrate of an enzyme?

5-10 Decarboxylation Test

Answer 3

Substrate is the molecule upon which an enzyme acts
Enzymes catalyze chemical reactions involving substrate

5-10 Decarboxylation Test

Question 4

Decarboxylase catalyze reactions that produce ____ (pH) products

5-10 Decarboxylation Test

Answer 4

Basic/Alkaline

5-10 Decarboxylation Test

Question 5

The pH indicator bromocresol purple is ____ at pH 6.8 and above ____ below pH 5.2

5-10 Decarboxylation Test

Answer 5

Purple
Yellow

5-10 Decarboxylation Test

Question 6

Why is mineral oil added to the decarboxylase broth before incubation?

5-10 Decarboxylation Test

Answer 6

To create an anaeriobic medium to promote fermentation

5-10 Decarboxylation Test

Question 7

Why does decarboxylase-positive tube have to turn yellow before it can turn purple?

*pH reversion and the order bacteria will digest sugars/peptone

5-10 Decarboxylation Test

Answer 7

Low pH is needed for bacteria to work. Sugar fermentation turns medium acidic, going from purple to yellow. Enzymes will digest peptones, turning pH back to basic (purple)

5-10 Decarboxylation Test

Question 8

Describe positive result in this experiment and describe negative result. What kind of pH is present in a (+) and (-) result?

*what is the purpose of this test?

5-10 Decarboxylation Test

Answer 8

(+): Purple media: decarboxylation took place, pH is alkaline, carboxyl groups got removed
(-): Yellow media: fermentation occurred but no decarboxylation, pH is acidic

5-10 Decarboxylation Test

Question 9

Why is glucose included in the decarboxylation broth?

*hint: answer is not “as a food source”

5-10 Decarboxylation Test

Answer 9

To create an acidic environment

5-10 Decarboxylation Test

Question 10

This decarboxylation test cannot be performed successfully on organisms that cannot ferment glucose. Explain why this is the case

*consider pH indicator

5-10 Decarboxylation Test

Answer 10

The medium will not turn acidic for the pH indicator to work and won’t produce the change in color needed for presence of decarboxylation

5-10 Decarboxylation Test

Question 11

Cadaverine and Putrescine are examples of compounds known as

5-10 Decarboxylation Test

Answer 11

Diamines

5-10 Decarboxylation Test

Question 12

The names, cadaverine and putrescine, suggest that the compounds might be found in ____ which they are, as a result of decarboxylation of ____ (what molecule) amino acids by bacteria

5-10 Decarboxylation Test

Answer 12

Cadavers
Proteins (amino acids)

5-10 Decarboxylation Test

Question 13

What is phenylalanine (what type of monomer is it)?

5-11 Phenylalanine Deaminase

Answer 13

Amino acid

5-11 Phenylalanine Deaminase

Question 14

Phenylalanine is part of an ingredient found in the popular artificial sweetners known as ____ or ____

*part ass, =

5-11 Phenylalanine Deaminase

Answer 14

Aspartme
Equal

5-11 Phenylalanine Deaminase

Question 15

The enzyme that some bacteria can produce that removes an amino group from phenylalanine is called

*name of the test

5-11 Phenylalanine Deaminase

Answer 15

Phenylalanine deaminase

5-11 Phenylalanine Deaminase

Question 16

The reagent that is added to bacterial growth on phenylalanine deaminase agar in order to determine if the enzyme has been produced, is ____

*FeCl3

5-11 Phenylalanine Deaminase

Answer 16

Ferric Chloride

Question 17

Describe a positive result in the experiment and a negative result

5-11 Phenylalanine Deaminase

Answer 17

(+): Green medium, bacteria broke down amine group, phenylalanine is present
(-): Yellow medium, no deaminase present

5-11 Phenylalanine Deaminase

Question 18

Phenylalanine is broken down to ____ and ____

*NH3 and an acid

5-11 Phenylalanine Deaminase

Answer 18

Ammonia
Phenylpyruvic acid

5-11 Phenylalanine Deaminase

Question 19

Why can’t you use a pH indicator to detect phenylalanine deaminase?

*neutralization

5-11 Phenylalanine Deaminase

Answer 19

You can’t use a pH indicator because the indicator and reagent will neutralize each other

5-11 Phenylalanine Deaminase

Question 20

A green color results in this experiment if ____ reacts with the reagent ____

*acid, FeCl3

5-11 Phenylalanine Deaminase

Answer 20

Phenylpyruvic acid
Ferric Chloride

5-11 Phenylalanine Deaminase

Question 21

Like all amino acids, phenylalanine is a source of two elements ___ and ___ for the bacteria

*N2 & C

5-11 Phenylalanine Deaminase

Answer 21

Nitrogen
Carbon

5-11 Phenylalanine Deaminase

Question 22

Write chemical equation for an amine group (amino group)

*2

5-11 Phenylalanine Deaminase

Answer 22

NH2

5-11 Phenylalanine Deaminase

Question 23

What is the difference between deamination and the decarboxylation of an amino acid?

*think of O2 requirements, refer to previous test/mineral oil

5-11 Phenylalanine Deaminase

Answer 23

Deamination reaction: aerobic
Decarboxylation reaction: anaerobic

5-11 Phenylalanine Deaminase

Question 24

Urea can be hydrolyzed to carbon dioxide and ____ by bacteria that produce the enzyme ___

*NH3, name of test

5-13 Urease Test (Urea Hydrolysis)

Answer 24

Ammonia
Urea

5-13 Urease Test (Urea Hydrolysis)

Question 25

Urinary tract pathogens from the genus ____ can be distinguished from other enteric bacteria by their rapid urease activity | *rhymes with genus, Pr ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 25

Proteus ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Question 26

What other disease is caused by this organism? | *refer to the genus, Pv/Pm ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 26

Diaper rash Caused by Proteus vulgaris & Proteus mirabilis ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Question 27

Urease-positive organisms break down urea to ____ which ____ the pH of the medium and changes the color of the pH indicator phenol red from ____ to ____ | *NH3, basic pH, acidic color to alkaline color ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 27

Ammonia Raises Yellow/Orange Pink ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Question 28

Describe a positive urease test and a negative urease test (include the relative pH) ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 28

(+): Pink medium: bacteria uses urease to breakdown urea/alkaline (1): Yellow/Pale orange medium: no urease present/acidic ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Question 29

In order for a urease-positive organism to turn the urea broth pink, the organism must ____ the pH of the medium enough to overcome the effects of the ____, potassium phosphate | *make the pH alkaline, keeps the pH constant ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 29

Raise/Increase Buffer ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Question 30

The urease test is an important part of the identification of the organism ____, that causes peptic ulcers | *helicopter ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 30

Helicobacter pylori ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Question 31

How does this organism (refer to #30) survive stomach acid? ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 31

Secretes urease enzymes that neutralize stomach acid so organisms can consume mucous membrane ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Question 32

A rapid urease test is performed on the ____ of patients with peptic ulcer symptoms ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 32

Majority ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Question 33

Why is it important that urease broth contain a buffer that can resist alkalinization of the medium from peptone metabolism? | *pH reversion factor ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 33

To not obtain false positive result from pH reversion of peptone metabolism

Question 34

Ammonia is used by many bacteria as a source of the element ____ | *N2 ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 34

Nitrogen ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Question 35

Bacteria use the element listed in #34, in order to make what two classes of macromolecules? | *DNA, RNA, amino acids ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Answer 35

Nucleic Acids Proteins ## Footnote 5-13 Urease Test (Urea Hydrolysis)

Question 36

TSI is a differential medium that is useful in differentiating _______ | *carbohydrates ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Answer 36

Bacteria that uses glucose, lactose, and sucrose ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Question 37

TSI agar contains 3 sugars in its recipe. The monosaccharide ____ is supplied in a low percentage (0.1%) while the disaccharide sugars ____ and ____ are provided in higher percentage (1%) | *3 sugars utilized in this test ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Answer 37

Glucose (0.1%) Lactose (1%) Sucrose (1%) ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Question 38

The result of TSI tubes are recorded according to the pH of ____ over the pH of the ____. The pH indicator in TSI is ____ which the color is ____ when it is acidic and ____ when it's alkaline | *K/A ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Answer 38

Slant Butt Yellow Red/Pink ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Question 39

Fermenters only capable of fermenting ____ will runout of sugar within the first few hours during incubation. Explain what these organisms do next and what the results look like in both the slant and butt | *glucose ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Answer 39

Carbohydrates Fermenters will metabolize proteins, leading to an alkaline reaction (pink slant/yellow butt) in the medium, yellow remains acidic due to initial fermentation ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Question 40

Fermenters capable of fermenting one or both disaccharides (sucrose and/or lactose) will never run out of sugar during the 24-hour incubation. Explain what TSI slant looks like in this case | *acidic result ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Answer 40

Yellow slant/butt ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Question 41

Besides sugar, other substrates found in TSI agar include ____ and ____. These substrates are a source of reducible ____, and digestion of these substrates leads to the formation of H2S | *biochemical sheet ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Answer 41

Cysteine Sodium Thiosulfate Sulfur ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Question 42

H2S is a colorless gas that smells like rotten eggs. It visually detected when a black color (precipitate) forms by reacting with the iron containing ingredient | *(NH₄)₂Fe(SO₄)₂·6H₂O ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Answer 42

Ferrous Ammonium Sulfate ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Question 43

H2S can be made by certain species of sulfur-reducing bacteria. The formation of H2S requires a reducing environment where excess hydrogren is present, and the pH is ___ | *H+ ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Answer 43

Acidic

Question 44

Explain why a K/K [H2S] result is not possible | *no H+ ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Answer 44

In order for H2S to be present, medium (at the butt) has to be acidic because it is an H+ donor ## Footnote 2-7 Triple Sugar Iron (TSI) Agar

Question 45

Enzymes that are released into the bacterial environment and work there are known as ____ | *they are RELEASING ## Footnote 5-14 Casease Test

Answer 45

Exoenzymes ## Footnote 5-14 Casease Test

Question 46

Bacteria that produce protein-digesting (proteolytic) enzymes break down large ____ to smaller ____ or individual ____ | *macromolecule ## Footnote 5-14 Casease Test

Answer 46

Proteins Polypeptides Amino acids ## Footnote 5-14 Casease Test

Question 47

Why do bacteria have to break down proteins in their environement (outside their cell) in order to use the protein as a food source? | *size of protein vs cell ## Footnote 5-14 Casease Test

Answer 47

Some proteins are too big to pass through cell membrane ## Footnote 5-14 Casease Test

Question 48

Why is milk opaque? Why does the milk agar turn clear when an organism produces casease enzyme? | *pancreatic casein, eaten ## Footnote 5-14 Casease Test

Answer 48

Milk contains the protein casein that makes the milk opaque Agar turns clear when casein is broken down, losing opacity ## Footnote 5-14 Casease Test

Question 49

Why is a polypeptide? What is the difference between a polypeptide and a peptide? Between a polypeptide and protein? Peptide and amino acid? | *10+, 2+, 1+, amine/carboxyl ## Footnote 5-14 Casease Test

Answer 49

Polypeptide: chain of 10+ amino acids Peptide: small chain of amino acids (2+) Protein: one or more polypeptide Amino Acid: protein monomer made of amine and carboxyl ## Footnote 5-14 Casease Test

Question 50

What is the difference between casein and pancreatic digest of casein? | *milk protein, peptone ## Footnote 5-14 Casease Test

Answer 50

Casein: found in milk Pancreatic digest of casein: breakdown of casein into 3 parts ## Footnote 5-14 Casease Test

Question 51

Why are whole, undigested proteins (as opposed to peptones), not usually included in the microbiological growth medium? | *protein vs. cell size ## Footnote 5-14 Casease Test

Answer 51

Bacteria can metabolize peptones better because of their small size. Proteins are large molecules. Peptones are better to use in media for a more accurate reading