quiz 3

Question 1

starch

example

Answer 1

large carbohydrate polysaccharide.
-glucoses linked by alpha bonds.
amylose

Question 2

starch hydrolysis

positive and negative

Answer 2

breaks carbohydrates down to short chains
-glucose
starch reacts with iodine: bright blue/black=starch
clear=starch degradation
starch agar: 0.4% soluble starch

Question 3

dextrose

Answer 3

another name for glucose

Question 4

lipids

Answer 4

fatty acids. high MW. lipases break lipids down.

Question 5

lipase test (lipid hydrolysis)

Answer 5

has tributryin (fatty acids 4 C long) and the dye spirit blue. 
clearing with blue is positive

Question 6

gelatin hydrolysis test

Answer 6

collagen-connective tissue. if you heat it up, it becomes gelatin.
gelatinases break peptide bonds and release amino acids
theres a clearing zone after adding TCA (trichloroacetic acid, precipitates proteins but not amino acids.)

Question 7

casein hydrolysis test

Answer 7

casein: protein in milk. when added to media, cloudy appearance.
without adding TCA, a clear zone is observed.

Question 8

Hydrogen sulfide production test purpose

Answer 8

differentiate sulfur reducing organisms from non reducing organisms

Question 9

Hydrogen sulfide production test
media 
protocoal 
enzyme/biochemical basis 
positive result

Answer 9

• SIM deep (sulfur, indole, motility) has cysteine and thiosulfate
• stab w needle
• 1. cysteine desulfurase- removes S from aa-forms H2S
     
     2. thiosulfate reductase- terminal e- acceptor for anerobic respiration-forms H2S.
• black precipitate

Question 10

h2s indicator is

Answer 10

ferrrous ammonium sulfate

Question 11

h2s sulfur containing amino acids:

Answer 11

methionine and cysteine.

Question 12

motility test purpose

Answer 12

detect bacterial motility

Question 13

motility test 
media 
protocoal 
enzyme/biochemical basis 
positive result

Answer 13

• 0.4% agar deep (tsa)
• stab w/needle
  1. tests for flagella
• cloudy-movement away from stab

Question 14

bile esculin test purpose

Answer 14

identify organisms capable of growing in presence of bile salts.

Question 15

2 products are formed when organisms hydrolyze the esculin in bile esculin test

Answer 15

glucose (glycolysis)

esculetin

Question 16

bile esculin test indicator

Answer 16

ferric ammonium citrate

Question 17

bile esculin test 
media 
protocoal 
enzyme/biochemical basis 
positive result

Answer 17

-bile esculin agar (slant)
-innoculate with loop (s motion)
1. does it grow in salts?(selective)
2. does it have enzyme to degrade esculin? (differential)
esculetin + glucose—> used by cell. esculetin + ferric —> brown precipitate. (positive)

Question 18

thiosulfate is reduced to

Answer 18

sulfite and hydrogen sulfide

Question 19

blood agar

Answer 19

non selective. has nutrients that allows growth of certain organisms. mix of tsa and sheep blood

Question 20

mannitol salt agar 
media 
protocoal 
enzyme/biochemical basis 
positive result

Answer 20

• msa
• streak w loop
  1. salt (selective bc inhibits growth of organisms that cant grow in 7.5% nacl)
  2. pH (differential) —> yellow pos.

Question 21

mannitol salt agar indicator is

Answer 21

phenol red.
if ph is below 6.8, phenol red turns yellow
if ph is above 8.4, stays pink

Question 22

hemolysis 
media 
protocoal 
enzyme/biochemical basis 
positive result

Answer 22

• BAP TSA + sheep blood
• streak
  1. Y (gamma, good)-no hemolysis
  2. alpha(intermediate)-some hemolysis —> greenish
  3. B(bad)- complete hemolysis—> clearing

Question 23

oxidase 
media 
protocoal 
enzyme/biochemical basis 
positive result

Answer 23

• tmpd
• drop of __ on paper rub bacteria- toothpick
  1. tmpd donates e to terminal cytochrome oxidase (enzyme in membrane bound)
• blue

Question 24

why use toothpick and not metal loop?

Answer 24

bc it’ll take all the electrons, give it false positive.

Question 25

catalase 
media 
protocoal 
enzyme/biochemical basis 
positive result

Answer 25

• h202
• drop on petri plate, add bacteria
  1. catalase (enzyme cytoplasm) turns h202 into h20+ 02.
• bubbles of 02.

Question 26

DNase
media 
protocoal 
enzyme/biochemical basis 
positive result

Answer 26

• tsa plate @ dna added
• streak, add in hcl
  1. DNase-exoenzyme degrades large molecule to dNMP’s for transport into cell.
• clearing

Question 27

superoxidate dismutase

Answer 27

02- + 2H+ –> h202

Question 28

catalase

Answer 28

h202—> h20 + 02

Question 29

peroxidase

Answer 29

h202 + nadh + h+ —> 2h20 + nad