LAB: EXP 2 (Isolation of Proteins)

Question 1

Proteins are made up of smaller units called _____

Answer 1

amino acids

Question 2

They are essential for the structure, function, and regulation of the body tissues and organs

Answer 2

Proteins

Question 3

Amino acids that have an amino group bonded directly to the alpha-carbon are referred to as _____

Answer 3

alpha amino acids

Question 4

the polar group is a hydroxyl (-OH) bonded to aliphatic hydrocarbon groups

Answer 4

serine and threonine

Question 5

the hydroxyl group (phenol) is bonded to an aromatic hydrocarbon group

Answer 5

tyrosine

Question 6

the polar side chain contains a thiol group (-SH)

Answer 6

cysteine

Question 7

contain amide groups in their side chains

Answer 7

Glutamine and asparagine

Question 8

Acidic amino acids

Answer 8

Glutamic acid, aspartic acid

Question 9

Basic amino acids

Answer 9

Histidine, lysine, and arginine

Question 10

Classification of amino acids according to polarity

Answer 10

• Uncharged non-polar
• Uncharged polar
• Charge polar

Question 11

Classification of amino acids according to nutritional availability

Answer 11

• Non-essential
• Essential

Question 12

Amino acids are linked together by ‘amide groups’ called _____.

Answer 12

peptide bonds

Question 13

During protein synthesis, the carboxyl group of amino acid at the end of the growing polypeptide chain reacts with the amino group of an incoming amino acid, releasing a molecule of _____

Answer 13

water

Question 14

Amino acid links to another to form a peptide through _____ and _____

Answer 14

peptide bond, condensation

Question 15

Identify the structure: Sequence of amino acid residues that serves as the backbone of a peptide chain or protein

Answer 15

Primary

Question 16

Function of the protein depends on the _____ structure

Answer 16

primary

Question 17

Identify the structure: Regular, repeating folding patterns

Answer 17

secondary

Question 18

Identify the structure: the “local” ordered structure brought about via H-bonding mainly

Answer 18

secondary

Question 19

Identify the structure: α-helix & β-pleated sheets

Answer 19

secondary

Question 20

Identify whether α-helix or β-pleated sheets: Rod-like structure

Answer 20

α-helix

Question 21

Identify whether α-helix or β-pleated sheets: N-H to C=O

Answer 21

α-helix

Question 22

Identify whether α-helix or β-pleated sheets: H-bonds in 4th succeeding amino acids

Answer 22

α-helix

Question 23

Identify whether α-helix or β-pleated sheets: H-bonds parallel to axis

Answer 23

α-helix

Question 24

Identify whether α-helix or β-pleated sheets: typically amphiphilic

Answer 24

α-helix

Question 25

Identify whether α-helix or β-pleated sheets: polypeptide chains are arranged side by side

Answer 25

β-pleated sheets

Question 26

Identify whether α-helix or β-pleated sheets: H-bonds form between chains

Answer 26

β-pleated sheets

Question 27

Identify whether α-helix or β-pleated sheets: parallel or antiparallel

Answer 27

β-pleated sheets

Question 28

Identify whether α-helix or β-pleated sheets: more stable

Answer 28

β-pleated sheets

Question 29

Identify the structure: The way the segments of the protein fold in 3 dimensions

Answer 29

tertiary

Question 30

Identify the structure: overall folding of domains

Answer 30

tertiary

Question 31

Identify the structure: specific overall shape of a protein

Answer 31

tertiary

Question 32

Identify the structure: cross links between R-groups of amino acids

Answer 32

tertiary

Question 33

Cross links in tertiary structures happen in:

Answer 33

o Disulfide o Ionic o Hydrophobic

Question 34

Identify the structure: Interaction between different polypeptide chains to produce an oligomeric structure

Answer 34

quaternary

Question 35

Identify the structure: Aggregates of two or more protein chain connected by weak non-covalent interactions

Answer 35

quaternary

Question 36

Identify the structure: Proteins with two or more chains

Answer 36

quaternary

Question 37

Yield only amino acids upon hydrolysis

Answer 37

Simple proteins

Question 38

Simple proteins + non-protein substances

Answer 38

Conjugated proteins

Question 39

Catalytic protein example

Answer 39

Enzymes

Question 40

Transport protein examples

Answer 40

Hemoglobin, transferrin, albumin

Question 41

Storage protein examples

Answer 41

Ovalbumin, casein, gliadin

Question 42

Contraction protein examples

Answer 42

Actin, myosin

Question 43

Gene regulation protein examples

Answer 43

Histones, non-histone nuclear

Question 44

Regulatory protein examples

Answer 44

Hormone, repressor proteins

Question 45

Immune protein examples

Answer 45

Antibodies, fibrin, complement

Question 46

Structural protein examples

Answer 46

Collagen, elastin, keratin

Question 47

Neurotransmission protein examples

Answer 47

Receptor proteins

Question 48

polypeptide chain/s folded into spherical or globular shape

Answer 48

globular protein

Question 49

soluble in aq. system

Answer 49

globular protein

Question 50

polypeptide chains arranged in long strands or sheets

Answer 50

fibrous protein

Question 51

water insoluble

Answer 51

fibrous protein

Question 52

Soluble in water and dilute aqueous solutions

Answer 52

Albumins (Plasma)

Question 53

Soluble in dilute salt solutions but are insoluble or sparingly soluble in water

Answer 53

Globulins (Serum)

Question 54

Soluble in dilute solutions of acids and bases; insoluble in neutral solvents

Answer 54

Glutelins (Flour)

Question 55

* Soluble 50-90% alcohol * Insoluble in water, neutral solvents, or absolute alcohol

Answer 55

Prolamins (Store protein in plants)

Question 56

Albumin-like that is insoluble in most ordinary solvents

Answer 56

Albuminoids/Scleroproteins

Question 57

A loss of three-dimensional structure sufficient to cause of loss of function

Answer 57

Protein Denaturation

Question 58

Denaturating agents

Answer 58

* Strong acids and bases * Organic solvents * Detergents * Reducing agents * Salts (salting in and salting out) * Heavy metals * Temperature

Question 59

Type of protein hydrolysis: uses a strong acid or base + high temperature

Answer 59

Complete hydrolysis

Question 60

Type of hydrolysis: Most commonly used reagent is 6N HCl

Answer 60

Acid hydrolysis

Question 61

In acid hydrolysis: ___ and ___ are partially destroyed

Answer 61

cys and tyr

Question 62

In acid hydrolysis, ___ is completely destroyed

Answer 62

trp

Question 63

In acid hydrolysis, ___ and ___ are incompletely liberated

Answer 63

val and ile

Question 64

In acid hydrolysis, ___ and ___ are racemized and destroyed

Answer 64

ser and thr

Question 65

Type of hydrolysis: uses NaOH or KOH

Answer 65

basic hydrolysis

Question 66

Advantage of basic hydrolysis

Answer 66

trp not destroyed

Question 67

Disadvantage of basic hydrolysis

Answer 67

arg, asn, gln, ser are destroyed

Question 68

Type of hydrolysis: uses enzyme called protease

Answer 68

Incomplete/partial hydrolysis

Question 69

_____ (eg. acid, base, enzyme) are needed to facilitate the hydrolysis of peptide bonds

Answer 69

Catalysts

Question 70

type of hydrolysis: presence of proteolytic enzymes results to partial or selective hydrolysis of polypeptide to yield a mixture of peptide fragments.

Answer 70

Enzymatic hydrolysis

Question 71

enzymes that hydrolyze peptide bonds at specific sites

Answer 71

proteases/peptidases

Question 72

Advantage of incomplete/partial hydrolysis

Answer 72

Amino acids are not affected

Question 73

Type of hydrolysis: requires certain temperature & pH conditions for optimum activity of enzymes

Answer 73

Incomplete/Partial hydrolysis

Question 74

Type of exopeptidase: cuts C-terminal residues except R,K and P

Answer 74

Carboxypeptidase A

Question 75

Type of exopeptidase: cuts C-terminal residues except R,K

Answer 75

Carboxypeptidase B

Question 76

Type of exopeptidase: cuts most N-terminal except when P is the next residue

Answer 76

Aminopeptidase

Question 77

Type of endopeptidase: cuts C side R & K

Answer 77

Trypsin

Question 78

Type of endopeptidase: cuts C side of F, Y, W

Answer 78

Chymotrypsin

Question 79

Type of endopeptidase: cuts C side of hydrophobic groups/aromatic R-groups

Answer 79

Papain

Question 80

Used in precipitation separation method and their solubility

Answer 80

- ammonium sulfate (sol) - polyethylene glycol (sol)

Question 81

Properties of proteins being considered during separation

Answer 81

o Charge o Molecular size, shape o Solubility o Affinity to a ligand o pI/IpH

Question 82

A procedure in which the pH of the protein mixture is adjusted to the pI of the protein to be isolated to selectively minimize its solubility.

Answer 82

Change in pH

Question 82

Casein: source and isolation method

Answer 82

* Source: Skimmed milk * Isolation method: Isoelectric precipitation

Question 83

Casein: type of protein

Answer 83

Phosphoprotein

Question 84

Isoelectric point of casein

Answer 84

4.6

Question 85

Mechanism of casein separation

Answer 85

PO4—3 interacts (ionic) with Ca+2 leading to polymerization of casein

Question 86

Albumin: source and isolation method

Answer 86

* Source: Skimmed milk * Isolation method: Denaturation and Coagulation by heat

Question 87

Albumin: type of protein

Answer 87

Globular protein (sol in water and diluted salt solutions)

Question 88

Second major protein in bovine milk and can serve as a regulator protein in lactose biosynthesis

Answer 88

Albumin

Question 89

Albumin is a _____ that can bind to several metal ions like calcium and zinc

Answer 89

metalloprotein

Question 90

Myoglobin: source and isolation method

Answer 90

* Source: Beef muscle * Isolation method: Salt-induced precipitation

Question 91

Color of isolated myoglobin precipitate

Answer 91

White

Question 92

Gluten: source and isolation method

Answer 92

* Source: Wheat flour * Isolation method: Solubility difference

Question 93

Gives bread its structure, texture, and elasticity

Answer 93

Gluten

Question 94

Gluten is a composite of _____ and ____, which exist, conjoined with starch

Answer 94

Prolamin and glutelin

Question 95

T/F: the isolated gluten should be positive of the iodin test

Answer 95

F. Should be negative.

Question 96

Role of gluten in bread making

Answer 96

traps the CO2 and gives off chewiness

Question 97

Solution used to test the complete removal of starch

Answer 97

I2

Question 98

Appearance of isolated gluten

Answer 98

Yellowish-white solid, tough, elastic, sticky