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Flashcards in Lab 8 Deck (30):
1

What is the substrate of the of the catalase test?

hydrogen peroxide

2

What is the enzyme of the of the catalase test?

catalase

3

What is the product of the of the catalase test?

water and oxygen gas

4

How is a positive and negative catalase test recognized?

Positive = bubbles Negative = no bubbles

5

What is the "why" of a positive catalase test?

Some bacteria contain catalase and some do not.

If we see bubbles its a positive test, if we do not see bubbles its a negative test. The bubbles are the oxygen gas end product. If catalase is being produced by the bacteria then oxygen should be released by the catalase reaction with hydrogen peroxide.

6

Would an aerobic or anerobic organism be more likely to produce catalase?

Aerobic, because they contain catalase which destroys hydrogen peroxide and converts it into water and oxygen gas.

An aerobic organism would be more likely to produce catalase because hydrogen peroxide is a toxic waste of oxygen and aerobic organisms use oxygen and anaerobicc organisms do not use oxygen so aerobic organisms would be more likely to have catalase to break down that toxic derivitive of oxygen into non-toxic products

7

What is the substrate of the starch hydrolysis test?

starch (in media)

8

What is the enzyme of the starch hydrolysis test?

 

amylase

 

9

What is the product of the starch hydrolysis test?

glucose

10

How is a positive or negative starch hydrolysis test recognized?

Positive: light or clear zone around the sample indicates amylase. Negative: Dark around the sample indicates no amylase present.

11

Explain the "why" of a positive starch hydrolysis test?

The cell releases amylase to break down the starch. A positive test is clear around the bacteria because we use a starch agar and they hydrolysize the starch in the area surrounding their growth. meaning they have the enzyme amylase present to hydrolyze the starch.

12

What is the function of the iodine in the starch hydrolysis test?

Iodine reacts with starch to produce a blue color. Iodine detects starch. Iodine reacts with starch and produces a blue or dark brown color, therefore, any microbial starch hydrolysis will be revealed as a clear zone surrounding the growth.

13

What is the substrate for the lipase test?

Lipid

14

What is the enzyme for the lipase test?

lipase

15

What is the product for the lipase test?

fatty acid + glycerol

16

Explain the "why" of a positive lipase test?

The fatty acids capture the spirit blue from surrounding medium to produce the blue halo. A positive test is recognized by a blue halo around the bacteria because the fatty acids capture the spirit blue from the surrounding medium to produce the blue halo. If there is no clear blue halo or if the media turns white, the bacteria hve not hydrolyzed the lipid so its a negative test.

17

How is a positive and negative lipase test recognized?

-Positive: clear blue halo -Negative: No clear blue halo or media turns white. This means the bacteria have not hydrolyzed the lipid.

18

What kind of macromolecule is gelatin?

Collagen

19

What is the substrate of the gelatin hydrolysis test?

Gelatin

20

What is the enzyme of the gelatin hydrolysis test?

gelatinases

21

What is the product of the gelatin hydrolysis test?

amino acids

22

How is a positive and negative gelatin hydrolysis test recognized?

-Liquid media is positive for gelatinase and solid media negative.

23

Explain the "why" of a positive gelatin hydrolysis test?

-If a microorganism is capable of hydrolyzing gelatin, the gelatin molecules close by are gradually broken down. A positive result is recognized by the gelatin liquifying. This is because the bacteria has gelatinase is capable of hydrolyzing gelatin, so the gelatin molecules in the immediate vicinity of the organism gradually are broken down. As a result, the gelatin remains liquified even when temperatures are lowered. A negative test is recognized if the gelatin remains in the solid state.

24

What is the substrate of a decarboxylase test?

amino acid

25

What is the enzyme of a decarboxylase test?

decarboxylase

26

What is the product of a decarboxylase test?

amine

27

What is the structure of the carboxyl group?

COOH

28

How is a positive and negative decarboxylase test recognized?

-Positive: stays purple -Negative: turns yellow

29

Explain "why" the positive result of the decarboxylase test turns the color it does.

-Decarboxylation of the amino acid results in accumulation of amines, which are alkaline and turns the medium purple. A positive test is recognized by it turning purple because decarboxylation of the amino acid results in accumulation of alkaline end products that turn the medium purple. A negative test does not turn purple, it turns yellow. If the organism is a glucose fermenter but does not produce the appropriate decarboxylase, the medium will turn yellow and remain so. If the organism does not ferment glucose, the medium will exhibit no color change.

30

What type of chemical reaction is a hydrolysis reaction?

-Breaking a bond using water. It is a decomposition reaction.