Lab 15

Question 1

large organic molecules

Answer 1

proteins

Question 2

subunits that make up a protein

Answer 2

amino acids

Question 3

Amino acids bond together by _____ forming a small chain (_____) or a larger molecule (______).

Answer 3

peptide bonds, peptide, polypeptide

Question 4

Bacteria can hydrolyze the _____ or ______ to release amino acids

Answer 4

peptides, polypeptides

Question 5

used primarily in anabolic reactions

Answer 5

amino acids

Question 6

large protein molecules, such as _____, are hydrolyzed by _____, and the smaller products of hydrolysis are transported into the cell.

Answer 6

gelatin, exoenzymes

Question 7

_______ dissolves in warm water (_____), solidifies (gels) when cooled below _____, and liquefies (sols) when heated to _____.

Answer 7

Nutrient gelatin, 50 C, 25 C, 25 C

Question 8

exoenzyme that hydrolyzes gelatin

Answer 8

gelatinase

Question 9

protein in milk

Answer 9

casein

Question 10

consists of skim milk and the indicator litmus

Answer 10

litmus milk

Question 11

Litmus milk medium is opaque due to ____ in colloidal suspension and the litmus is ____.

Answer 11

casein, blue

Question 12

hydrolysis of the milk proteins

Answer 12

peptonization

Question 13

Litmus milk is also used to detect _____, because litmus turns pink in the presence of acid.

Answer 13

lactose fermentation

Question 14

Excessive amounts of acid will cause ______ of the milk

Answer 14

coagulation (curd formation)

Question 15

_________ will result in an alkaline (purple) reaction of litmus milk.

Answer 15

catabolism of amino acids

Question 16

Some bacteria can _____, causing the litmus indicator to turn white in the bottom of the tube.

Answer 16

reduce litmus

Question 17

waste product of protein digestion and is excreted in the urine

Answer 17

urea

Question 18

enzyme that liberates ammonia from urea

Answer 18

urease

Question 19

contains peptone, glucose, urea, and phenol read. The pH of the prepared medium is 6.8 (phenol red turns yellow)

Answer 19

urea agar

Question 20

During incubation in urea agar, bacteria possessing urease produce _____, which _____ the pH of the medium, turning the indicator _____ at pH ____

Answer 20

ammonia, raises, fuchsia, 8.4

Question 21

After hydrolysis, the pH of urea agar is _____

Answer 21

high (basic)

Question 22

After hydrolysis, gelatin will _____ at 22 C

Answer 22

liquefy