Qualitative Reaction of Proteins (Lab)

Question 1

are macromolecules that are made from one or more chains of polypeptides

Answer 1

proteins

Question 2

are linear polymers making up proteins

Answer 2

polypeptides

Question 3

Polypeptides are linear polymers made up from smaller molecules called

Answer 3

amino acids

Question 4

Polypeptides
are formed when amino acids are joined together via typical ___bonds that forms between
amino group of one amino acid and carboxyl group

Answer 4

peptide

Question 5

Proteins are the structural building blocks of almost all major cellular components and
structures, such as

Answer 5

enzymes
ribosomes
cytoskeleton
centrosomes
proteasomes

Question 6

There are more than _
different amino acids found in biological organisms

Answer 6

20

Question 7

Amino acids have characteristic chemical and
structural features

Answer 7

amino group (-NH2)
carboxyl group (-COOH)

Question 8

They have an amino group (-NH2) plus a carboxyl group (-COOH) as functional
groups which are covalently attached to the

Answer 8

first (a) carbon atom

Question 9

Proteins can be visualized and be tested with the help of series of unique dyes, such as

Answer 9

biuret reagent
coomasie blue (lowry reagent)

Question 10

Amino acids can be visualized and be tested for with the help of a
chemical reagent called

Answer 10

ninhydrin

Question 11

However, a simple and relatively quick qualitative test for the
presence of amino acids in solution is the

Answer 11

Whatman filter paper spotting test

Question 12

is performed to analyze proteins in solid samples

Answer 12

ninhydrin test

Question 13

samples for protein qualitative analysis

Answer 13

egg albumin
diluted honey
potato starch
milk
egg yolk
glucose
amino acid
meat (pork,fish)
egg white
cooked rich

Question 14

biuret reagent

Answer 14

sodium hydroxide
copper (II) sulfate
potassium sodium tartate

Question 15

very poisonous

Answer 15

ninhydrin

Question 16

inhaling the fumes of ___ is not advisable

Answer 16

ninhydrin

Question 17

amino acid common structure (3)

Answer 17

amino group
carboxyl group
variable side chain (R group)

Question 18

gives the amino acid its unique chemical properties.

Answer 18

R group

Question 19

The specific sequence of amino acids in a protein is the

Answer 19

primary structure

Question 20

This structure may be recited by naming each amino acid beginning on the _-terminus.

Answer 20

N terminus

Question 21

Proteins twist, turn, and fold into complex three dimensional shapes.

what structure

Answer 21

tertiary structure

Question 22

These twists and turns are possible because there is ____ of the bonds around the α-carbon of each amino acid.

Answer 22

free rotation

Question 23

sequence of amino acids in a polypaptide chain, similar to the sequence of letters that spell out a specific word

what structure

Answer 23

primary structure

Question 24

the corkscrew like twists or pleated folds formed by hydrogen bonds between amino acids in the polypeptide chain

what structure

Answer 24

secondary structure

Question 25

the complex three dimensional shape formed by multiple twists and bends in the polypeptide chain, based on the side chains interactions with each other and the aqueous solvent

Answer 25

tertiary structure

Question 26

two or more polypeptide chians bonded together what structure

Answer 26

quaternary structure

Question 27

positive test for biuret indicates

Answer 27

protein is present

Question 28

biuret positive test

Answer 28

purple

Question 29

In the presence of alpha (α)-amino acids what is observed in ninhydrin test

Answer 29

blue to blue violet color

Question 30

ninhydrin reagent

Answer 30

ninhydrin in 10ml of either ethanol or acetone.

Question 31

deep purple positive for ninhydrin means

Answer 31

For ammonia, primary/secondary amines, and amino acids

Question 32

yellow positive for ninhydrin means

Answer 32

hydroxyproline and proline

Question 33

brown positive for ninhydrin means

Answer 33

asparagine

Question 34

organic macromolecules containing C,H,O,N

Answer 34

proteins

Question 35

examples of proteins

Answer 35

enzymes body tissues many immune system cells

Question 36

monomers of proteins

Answer 36

amino acid

Question 37

amino acids joint to form small protein polymers called

Answer 37

peptides

Question 38

long protein polymers are called

Answer 38

polypeptides

Question 39

its characteristic that is critical to function

Answer 39

folded

Question 40

sources of protein

Answer 40

beans grams lentils peas soya beans eggs paneer fish meat milk

Question 41

are macromolecules that are made from one or more chains of polypeptides

Answer 41

proteins

Question 42

linear polymers made up from smaller molecules

Answer 42

polypeptides

Question 43

polypeptides are formed when amino acids are joined together via typical ___ bonds

Answer 43

peptide bonds

Question 44

amino acid common core structure

Answer 44

amino group (-NH2) carboxyl group (COOH) R group

Question 45

functional group which are covalently attached to the first (a) carbon atom

Answer 45

carboxyl group

Question 46

part that gives the amino acid its unique chemical properties

Answer 46

R group

Question 47

basic functional group

Answer 47

amino group

Question 48

side chains; wild card structure

Answer 48

R groups

Question 49

acidic functional group

Answer 49

carbonyl group

Question 50

polar in nature

Answer 50

carbonyl group

Question 51

essential amino acids

Answer 51

Phenylalanine Valine Tryptophan Threonine Isoleucine Methionine Histidine Leucine Lysine

Question 52

conditionally essential amino acid

Answer 52

arginine cysteine proline tyrosine glutamine glycine

Question 53

nonessential amino acids

Answer 53

alanine asparagine aspartic acid glutamic acid serine

Question 54

arrangement of amino acids what structure

Answer 54

primary structure

Question 55

protein structure levels that has hydrogen bonds

Answer 55

secondary structure

Question 56

protein structure levels that has alpha helix and beta-pleated sheet

Answer 56

secondary structure

Question 57

protein structure levels that has R group interactions

Answer 57

tertiary structure

Question 58

proteins with more than 1 polypeptide subunit

Answer 58

quaternary structure

Question 59

specific sequence of amino acids in a protein is the

Answer 59

primary structure

Question 60

which starting terminus a protein can be recited by naming each amino acid

Answer 60

N-terminus

Question 61

twist, turn, and fold into complex three dimensional shapes

Answer 61

proteins

Question 62

why is twists and turns possible in protein

Answer 62

free-rotation of the bonds around the a-carbon of each amino acid

Question 63

which sample is used for biuret test

Answer 63

egg albumin diluted honey potato starch milk egg yolk glucose amino acid

Question 64

filter paper test samplpe

Answer 64

amino acids

Question 65

ninhydrin test sample

Answer 65

meat (pork,fish) egg white cooked rice

Question 66

biuret test procedures

Answer 66

pipette 2ml of the solutions (distilled water, egg albumin, diluted honey, potato starch, glucose solution, egg yolk, amino acid) add one dropperful of Biuret reagent into each of the test tubes and gently mix place the tubes back into the rack and incubate contents for about 2 minutes at your work bench

Question 67

specific for peptide bond

Answer 67

biuret test

Question 68

substances containing not less than two peptide linkages give this test

Answer 68

biuret test

Question 69

principle of biuret test

Answer 69

when proteins and peptides treated with an alkaline solution of dilute copper sulfate, a violet color is formed

Question 70

what characteristic of biuret test result is proportional to the amount of proteins present

Answer 70

color density

Question 71

biuret agent is what kind of solution

Answer 71

alkaline copper sulfate

Question 72

chemical reation to detect existence of amino acids

Answer 72

ninhydrin reaction

Question 73

used for liquid samples

Answer 73

filter paper test

Question 74

indicate that there is an amino acid in the spot solution

Answer 74

purple stians

Question 75

gives a yellow colour because it is a secondary amine

Answer 75

proline

Question 76

how many sample is used for ninhydrin test

Answer 76

2 mg

Question 77

how much to boil test mixture in ninhydrin test

Answer 77

15-20 seconds

Question 78

what is observed when there is alpha amino acid in ninhydrin test

Answer 78

blue-violet color

Question 79

result of distilled water in biuret test

Answer 79

negative result

Question 80

biuret test result of egg albumin

Answer 80

violet/purple color (+)

Question 81

biuret test result of diluted honey

Answer 81

yellow (-)

Question 82

biuret test result of potato starch

Answer 82

negative (-)

Question 83

biuret test result of glucose solution

Answer 83

-

Question 84

biuret test result of egg yolk

Answer 84

positive (+)

Question 85

result of amino acids in biuret test Tyrosine Proline Tryptophan Asparagine

Answer 85

All positive but proline will be yellow in color instead of purple

Question 86

ninhydrin test result of distilled water

Answer 86

negative

Question 87

ninhydrin test result of asparagine

Answer 87

positive (blue or purple color)

Question 88

ninhydrin test result of proline

Answer 88

positive (yellow color)

Question 89

ninhydrin test result of tryptophan

Answer 89

purple (+)

Question 90

ninhydrin test result of tyrosine

Answer 90

purple (+)

Question 91

ninhydrin test result of pork meat

Answer 91

positive (+)

Question 92

ninhydrin test result of salmon

Answer 92

positive (+)

Question 93

ninhydrin test result of egg white

Answer 93

(+)

Question 94

ninhydrin test result of cooked rice

Answer 94

(+)

Question 95

1. In the test for proteins, which structure in the proteins does the Biuret reagent reacts with?

Answer 95

The Biuret reagent reacts with the peptide bonds in proteins. Peptide bonds are the chemical links between amino acids that form the primary structure of a protein. When the Biuret reagent, which contains copper sulfate, interacts with these peptide bonds, it forms a violet-colored complex. This color change indicates the presence of proteins.

Question 96

3. Which amino acid solutions resulted positive with the Ninhydrin Test? Explain.

Answer 96

all but proline will be yellow since it has a secondary amine group