skills 10

Question 1

selective media

Answer 1

growth of certain bacteria is selectively inhibited

Question 2

differential media

Answer 2

differences in appearance occur among different growing bacteria

Question 3

exoenzyme

Answer 3

enzymes secreted into environment to break down food particles into components bacteria can absorb

Question 4

skim milk agar test

{purpose}

Answer 4

• determines the ability of the organism to degrade the casein protein
• differentiate the organism on the basis of the production of the exoenzyme proteinase / caseinase

Question 5

reactant

Answer 5

substance taking part in chemical reaction

Question 6

reagent

Answer 6

substance / compound added to system to cause a chemical reaction / test if reaction occurs

Question 7

product

Answer 7

substance present at the end of a chemical reaction

Question 8

what is the casein agar / skim milk agar growth medium used to detect?

Answer 8

hydrolytic microorganisms

Question 9

substrate

Answer 9

molecule upon which an enzyme acts

Question 10

skim milk agar test results

Answer 10

positive= digests protein ➡ clearing around colony
negative= no clearing around or underneath colony

Question 11

skim milk agar test products

Answer 11

small chains of amino acids; dipeptides; polypeptides

Question 12

skim milk agar test media

Answer 12

skim milk agar / casein agar

Question 13

DNAse agar test

{purpose}

Answer 13

• differentiate organisms on the ability to produce DNAse enzyme
• can be used to differentiate between pathogenic organisms (since breaking down DNA is a virulence factor)

Question 14

in DNAse agar test, methyl green + DNA=what color?

Answer 14

green

Question 15

in DNAse agar test, methyl green - DNA= what color?

Answer 15

colorless

Question 16

DNAse agar test products

Answer 16

free nucleotides / oligonucletides (short DNA molecules); phosphate

Question 17

DNAse test media

Answer 17

DNAse test agar base w/ indicators methyl green

Question 18

DNAse test results

Answer 18

positive= DNAse degrades DNA ➡ dye is release & reverts to colorless
negative= absence of clear zone; green / no change in color

Question 19

spirit blue agar test

{purpose}

Answer 19

uses pH indicator dye (spirit blue) ; breaks down lipids ➡ fatty acids & glycerol; presence of fatty acids is determined by change in pH

Question 20

spirit blue agar test products

Answer 20

fatty acids

Question 21

spirit blue agar test media

Answer 21

lipids & pH indicator dye (spirit blue)

Question 22

spirit blue agar test results

Answer 22

positive= thin clear strip surrounding dark blue bacterial lawn
negative= all clear / blend in

Question 23

starch agar

{purpose}

Answer 23

differential medium that tests the ability of an organism to produce amylase ➡ hydrolyzes starch

Question 24

starch agar test products

Answer 24

maltose. glucose, dextrins

Question 25

starch agar test media

Answer 25

starch agar

Question 26

starch agar results

Answer 26

after flooding plate with iodine
positive= light clear area surrounding bacteria
negative= no lightness around bacteria