Ex. 18 Selected Microbial Enzymes

Question 1

bacterial physiology

Answer 1

the biochemistry or biochemical characteristic of bacterial cells

Question 2

metabloism

Answer 2

sum of all chemical rxns

Question 3

exoenzymes

Answer 3

acts on substances outside cell, mainly hydrolytic enzymes that break down macromolecules by hydolysis (adding H+ and OH- ions from H20)

Question 4

why use exoenzymes

Answer 4

high molecular weight substances cannot pass through cells. too big. must be degraded

Question 5

endoenzymes

Answer 5

fn inside cells, synthesis of new protoplasmic requirements and production of cellular nrg from assimilated materials

Question 6

amylase

Answer 6

exoenzymes, hydrolyses starch (split by addition of water)

Question 7

starch

Answer 7

polysaccharide, high molecular weight, branching polymers of glucose. source of carbon and nrg. cleaved into monosaccharides, taken into cell and degraded by endoenzymes

Question 8

iodine in presence of starch turns

Answer 8

blue brown. no colour means starch is degraded by amylase

Question 9

catalase

Answer 9

enzyme breaks down H202 into water and 02

2H202 —–> 2H2O + O2

Question 10

hydrogen peroxide

Answer 10

toxic byproduct of aerobic respiration formed when H atoms combine with O2

Question 11

which genera do not produce catalse

Answer 11

anaerobic bacteria and damaged by H202. Streptococcus, Enterococcus, Lactobacillus can survive oxygen atmosphere w/o producing enzymes to degrade peroxide

Question 12

positive test for catalase

Answer 12

h202 and bactera. bubbles means o2 gas being produced

Question 13

fn of pmf

Answer 13

generate ATP, rotate flagella, transport solute across cytoplasmic membrane, etc

Question 14

in aerobic respiration what is the final enzyme complex and TEA

Answer 14

oxidase complex. O2

Question 15

name some oxidase comlex

Answer 15

quinol oxidases (oxidize quinones), cytochrome c oxidase (oxidize cytochrome c)

Question 16

which bacteria have quinol oxidases and cytochrome c oxidase

Answer 16

quinol oxidases Escherichia col, Enterobacteriaceae

cytochrome c oxidase Pseudomonas aeruginosa

Question 17

oxidaste test

Answer 17

detect cytochrome c using chromogenic reducing agent. does not directly detect cytochrome c but the oxidized cytochrome c

Question 18

chromogenic reducing agent

Answer 18

chemical that changed or produces colour as it becomes oxidized

Question 19

results of oxidizes test

Answer 19

in redox rxn, colourless reagent is oxidized and cytochrome c reduced. oxidized form of reagent is maroon/black

Question 20

two fermentative pathways that produce hydrogen sulphide gas (H2S)

Answer 20

cysteine desulphydrase and reduction of thiosulfate

Question 21

cysteine desulphydrase

Answer 21

enzyme strips cysteine of both its sulfhydyl (-SH) and amino group. yields H2S, ammonia NH3 and pyruvic acid

Question 22

reduction of thiosulfate

Answer 22

enzyme thiosulfate reductase reduces thiosulphate, an inorganic sulfur compound to produce H2S

Question 23

Triple sugar agar

Answer 23

medium for test of reduction of thiosulfate. contains peptone (digest of protein) and sodium thiosulfate that serve as sulfur substrate

Question 24

ferrous sulfate

Answer 24

H2S indicator, H2S is colourless but will react w/ferrous sulphate to make ferrous sulphide which blackens medium. run involves metal ions not enzymes

Question 25

H2S (hydrogen sulfide) + FeS04 (ferrous sulfate) --->

Answer 25

FeS (ferrous sulphide) black precipitate + H2S04 sulphuric acid