Post Lab Exp 3: Proteins

Question 1

is the most abundant substance in the cell next to water

Answer 1

Protein

Question 2

Protein comprises ___% of its over-all mass

Answer 2

15%

Question 3

Protein is composed of ______ as its building block.

Answer 3

amino acids

Question 4

Protein is linked together with peptide bonds with a positive charged ______ containing group at one end and a negatively charged ____ group

Answer 4

positive charge nitrogen group
negative charge carboxyl-group

Question 5

– a dipeptide, a sweetener that has no sugar
component

Answer 5

Aspartame

Question 6

– a tripeptide
– an antioxidant that prevents
damage to cellular
components caused by free
radicals.

Answer 6

Glutathione

Question 7

General test for proteins,
detecting peptide bonds

Answer 7

Biuret Test

Question 8

Reagents of Biuret Test

Answer 8

KOH, hydrated
CuSO4
, Potassium sodium
tartarate

Question 9

Positive result of Biuret Test

Answer 9

– Violet solution

Question 10

General test for proteins
except proline (yellow)

Answer 10

Ninhydrin

Question 11

Test for the –NH2 group in
free amino acid

Answer 11

Ninhydrin Test

Question 12

What is the Reagent of Ninhydrin

Answer 12

Ninhydrin

Question 13

Positive result of Ninhydrin Test

Answer 13

Positive Result - a deep blue
or purple color solution

Question 14

Test for indole group,
tryptophan

Answer 14

Hopkins-Cole Test

Question 15

Reagent of Hopkins-Cole Test

Answer 15

Hopkin’s Cole
reagent and conc. H2SO4

Question 16

Hopkins Cole Test Positive Result

Answer 16

Positive Result: purple ring at
the interface of two liquids

Question 17

The indole group of tryptophan reacts with _____ in the presence
of concentrated H2S04
to give a purple color

Answer 17

glyoxylic acid

Question 18

Test for activated aromatic rings,
Tyrosine and tryptophan

Answer 18

Xanthoproteic Test

Question 19

What are the reagents of Xanthoproteic Test

Answer 19

Reagents: Conc. Nitric Acid,
ammonium hydroxide

Question 20

What is the Positive Result if Xanthoprotei Test

Answer 20

Positive result: Yellow or dark orange
solution or precipitate

Question 21

When the sample is treated with a concentrated nitric acid it undergoes
______ with the aromatic amino acids such as tyrosine and tryptophan
and forms a yellow colored

Answer 21

nitration

Question 22

In Xanthoproteic test, ________ is not an activated benzene ring so it will not react

Answer 22

Phenylalanine

Question 23

Test for guanidine group,
arginine

Answer 23

Sakaguchi Test

Question 24

What are the reagents of Sakaguchi Test

Answer 24

Reagent: α-Naphthol and a drop
of sodium hypobromite

Question 25

What is teh positive result for sakaguchi test?

Answer 25

red-colored
complex solution