micro quiz 3/21

Question 1

Hydrolysis

Answer 1

reactions that use water to split complex molecules apart

Question 2

Hydrolytic enzymes

Answer 2

are those that catalyze hydrolytic reactions

Question 3

Intracellular

Answer 3

catalyze the reaction inside the cell

Question 4

Extracellular

Answer 4

secreted, catalyze the reaction outside the cell (aka. exoenzymes)

Question 5

exoenzymes

Answer 5

All the enzymes we are testing for today are exoenzymes, meaning they are secreted into the medium
They will either:
* Create a halo of clearing of the substrate (starch agar, DNase agar, milk agar)
* Liquify the surrounding medium (gelatin agar)

Question 6

Amylase test ( starch hydrolysis)
Why is starch broken down and how

Answer 6

Starch is too big to pass through the bacterial cell wall, so for microbes to use it they
secrete enzymes to break down the polysaccharide before bringing it into the cell

Question 7

Starch

Answer 7

polysaccharide made up of α-D-glucose subunits
* Amylose = unbranched
* Amylopectin = branched

Question 8

what does the amylase test identify

Answer 8

Aids in differentiating members of the genera Corynebacterium, Clostridium, Bacillus, Bacteroides, Fusobacterium, and Enterococcus most of which have both amylase + and - species

Question 9

amylase positive result

Answer 9

Organisms positive for α-amylase and/or oligo-1,6-glucosidase will have a zone of
clearing around the growth
reagent: iodine (brownish to blue when bound to starch polymers)

Question 10

which organisms can hydrolyze starch

Answer 10

Organisms that produce and secrete α-amylase and oligo-1,6-glucosidase
are able to hydrolyze starch

Question 11

DNase test

Answer 11

DNase is the enzyme that breaks down DNA
-Organisms that produce and secrete DNase will have a zone of clearing around the growth
- used to distinguish gram-positive from negative
- results are shown by zone clearings

Question 12

Lipase test

Answer 12

Lipase is an exoenzyme that can hydrolyze fats into smaller monoglycerides and glycerol
-Next week look for the clearing of lipids around bacterial growth

Question 13

Gelatinase Test

Answer 13

Gelatin is a protein derived from collagen
-Gelatinases are a family of exoenzymes that can hydrolyze gelatin
into individual amino acids

Question 14

Gelatinate formula

Answer 14

Gelatin > Gelatinase (with H2O)> Polypeptides ( gelatinase again ( enzyme)) > Amino Acids