Experiment 1: General Properties of Proteins

Question 1

What qualitative tests for proteins were conducted during the experiment?

Answer 1

1. Biuret Test
2. Ninhydrin Test

Question 2

What composes the Biuret’s reagent?

Answer 2

• NaOH (sodium hydroxide)
• copper (II) sulfate

Question 3

What does the Biuret Test test for?

Answer 3

peptide bonds

Question 4

What is the positive result of the Biuret Test?

Answer 4

purple complex solution

Question 5

What reagent(s) is/are used for the Ninhydrin Test?

Answer 5

ninhydrin solution

Question 6

What does the Ninhydrin Test test for?

Answer 6

• free hydrogen amino group
• detect alpha amino acid

Question 7

What is the positive result of the Ninhydrin Test?

Answer 7

purple complex solution

Question 8

TRUE or FALSE

Denaturation can be permanent or temporary

Answer 8

TRUE

Question 9

What are the 7 methods of denaturing proteins?

Answer 9

1. Thermal & Radiation
2. Mechanical
3. Acids & Bases
4. Organic Solvents
5. Heavy Metals
6. Alkaloid Reagents
7. Enzymes

Question 10

Identify:

Denaturation of proteins by heating in a water bath

Answer 10

Thermal & Radiation

Question 11

Identify

Denaturation of proteins by stirring vigorously using a stirring rod

Answer 11

Mechanical

Question 12

Identify:

Denaturation of proteins by adding concentrated hydrochloric acid

Answer 12

Acids & Bases

Question 13

Identify

Denaturation of proteins by adding 70% ethanol

Answer 13

Organic Solvents

Question 14

Identify:

Denaturation of proteins by adding 1.0 M copper (II) sulfate solution

Answer 14

Heavy Metals

Question 15

Identify:

Denaturation of proteins by adding picric acid solution

Answer 15

Alkaloid Reagents

Question 16

Which method is the best in denaturing?

Answer 16

Enzymes

Question 17

Describe the principle behind salting-out.

Answer 17

Interaction with ammonium sulfate is prioritized. Salt ions would compete interaction