BACTERIAL ENZYMES

Question 1

What are the enzymes called that accomplish in splitting/breaking down large complex molecules of polysaccharides, proteins or lipids? (They also do this thru hydrolysis)

Answer 1

Extracellular

Question 2

How are the extracellular enzymes accomplish the breakdown of their respective substrates?

Answer 2

Hydrolysis

Question 3

T or F:
Carbohydrases such as amylase hydrolyze polysaccharides to sugars

Answer 3

TRUE

Question 4

T/F:
Proteases hydrolyze lipids to lipoic acids and peptides

Answer 4

FALSE, proteases hydrolyze proteins to peptides and amino acids

Question 5

What do lipases hydrolyze lipids to?

Answer 5

Lipases hydrolyzes lipids to glycerol and fatty acids

Question 6

What evidence is obtained when organisms are grown in a medium containing one of the substrates (carbohydrases/proteases/ lipases)

Answer 6

Evidence of degradation

Question 7

What are the examples of endoenzymes?

Answer 7

Catalase and oxidase

Question 8

T/F:
Does catalase act on hydrogen peroxide to break down into hydrogen and oxygen?

Answer 8

TRUE

Question 9

What are the oxidative end product of aerobic respiration (catalase)?

Answer 9

H2O and O2

Question 10

What are the broth cultures used for the bacterial enzyme experiment?

Answer 10

Escherichia coli, Pseudomonas aeruginosa (lvl 2), Bacillus subtilis

Question 11

What are the 3 agar plates used for the bacterial enzymes?

Answer 11

Starch (carbohydrates), Tween 80 (fat), skim milk (protein)

Question 12

T/F:
Oxidase activates the ocidation of reduced cytochrome c by molecular oxygen in aerobic organisms during electron transport

Answer 12

TRUE

Question 13

What is the result of iodine in the presence of starch?

Answer 13

formation of a dark blue-black colour

Question 14

For the evidence of carbohydrase (amylase), what will appear if the starch has been hydrolyzed by the production of amylase?

Answer 14

clear zone will appear surrounding the growth of organisms

Question 15

Does the hydrolysis of lipids, leading to the production of glycerol and fatty acids, result in the formation of a precipitate that causes cloudiness or turbidity?

Answer 15

Yes

Question 16

What is the formation of precipitate, which will be cloudy or turbid, mean?

Answer 16

The products (fatty acid and glycerol) of hydrolysis of the lipid result

Question 17

What is a casein?

Answer 17

Casein is the principal nitrogenous (protein) constituent in milk

Question 18

What is the casein responsible for, and how does it exist?

Answer 18

It exists in a collodial state and is responsible for the whiteness of milk

Question 19

A milk agar when a protease is hydrolyzed (casein), shows a soluble product and a ____ will surround the streak of bacterial growth

Answer 19

zones of clearing/clear zone

Question 20

Exoenzyme Activity:

What are the results of starch hydrolysis, lipolysis, and proteolysis
* E.coli
* B. subtilis
* P. aeruginosa

Answer 20

• -ve for E.coli
• +ve for B. subtilis
• -ve, +ve, +ve for P. aeruginosa

Question 21

What reagent was used to develop a purple to black colour

Answer 21

tetramethyl-p-phenylenediamine reagent

or Oxidase reagent

Question 22

Endoenzyme activity

what are the types of organisms that had presence of enzyme in catalase?

Answer 22

E.coli, B. subtilis, and P. aeruginosa

Question 23

what are the types of organisms that had absence of enzyme in oxidase?

Answer 23

E.coli and B. subtilis

Question 24

What is the difference between an endoenzyme and exoenzyme?

Answer 24

Endoenzyme - the ones that work inside the cell and carry out intracellular biochemical reactions

Exoenzymes - proteins enzymes that work outside the cell

Question 25

What is the substrate of the catalase reaction? Why are bubbles produced in a positive catalase test?

Answer 25

the substrate of the catalase reaction is hydrogen peroxide and bubbles are produced because of the oxygen gas

Question 26

T/F:
If catalase is very active due to an abundance of hydrogen peroxide, bubbles are produced.

Answer 26

TRUE

Question 27

How do the methods for the detection of hydrolysis differ between these 3 tests (bacterial enzymes)

Answer 27

• Casein: uses clear zone to determinepositive & negative
• Starch : adds gram iodine to determine
• Lipids : resulting in products of glycerol and fatty acid with formation of precipitate that will be cloudy/turbid

Question 28

Which of the following is indicative of lipase activity on Tween 80 agar?

Answer 28

Turbid/cloudy medium

Question 29

Which of the following organisms has oxidase activity?

Answer 29

Pseudomonas aeruginosa