Chapter 2: Proteins

Question 1

Who is the swedish chemist that coined the term protein?

Answer 1

Jons Jacob Berzelius

Question 2

What does the word protein was derived?

Answer 2

Proteios meaning first

Question 3

What are the four elements of protein?

Answer 3

Carbon, hydrogen, oxygen, nitrogen

Question 4

Does every protein contains 20 amino acids? Why or why not?

Answer 4

No, not every protein contains all 20 types of amino acids but most proteins contain most.

Question 5

What do you call the common amino acids and why are the called as common amino acids?

Answer 5

a-amino acids because they have a primary amino group (-NH2) as a substituent of the a carbon atom, the carbon next to carboxylic acid group (-COOH)

Question 6

What is the sole exception of a-amino acid? and why?

Answer 6

Proline because it has a secondary amino group (-NH-)

Question 7

How does the 20 amino side chains differ?

Answer 7

differ in the structure of their side chains (R groups)

Question 8

What is an amino acid?
draw or visualize its structure

Answer 8

a molecule that has an amine and carboxyl group

Question 9

At physiological pH, what happens to amino and carboxylic acid?

Answer 9

Amino groups- protonated
Carboxylic acid groups - conjugated base (carboxylate) forms

Therefore, it can act both as an acid and base

Question 10

What is dipolar ions or zwitterions?

Answer 10

This bear charged groups of opposite polarity.

Question 11

Which is amino acids like other ionic compound more soluble?

Answer 11

Soluble more in polar solvent than in nonpolar solvents

Question 12

What do you call the process in which amino acids can be polymerized to form chains and it is a bond formation with the elimination of a water molecule?

Answer 12

Condensation process

Question 13

What do you call the resulting CO- NH linkage ( amide linkage)?

Answer 13

Peptide bond

Question 14

What are these polymers composed of two, three, a few (3–10), and many amino acid
units are known?

Answer 14

dipeptides, tripeptides, oligopeptides, and
polypeptides

Question 15

After they are incorporated into a peptide, the individual
amino acids (the monomeric units) are referred to as amino acid _________?

Answer 15

residues

Question 16

What do you call a residue with a a free amino group?

Answer 16

amino terminus or N-terminus

Question 17

What do you call a residue with a a free carboxylate group?

Answer 17

carboxyl terminus or C-terminus

Question 18

How to classify the amino acids?

Answer 18

polarities of their side chains

Question 19

3 major types of amino acids

Answer 19

nonpolar R groups, uncharged polar R groups, charged polar R groups

Question 20

What are the nine nonpolar amino acid?

Answer 20

GAVLIMPPT

Glycine
Aline
Valine
Leucine
Isoleucine
Methionine
Proline
Phenylalanine
Tryptophan

Question 21

smallest possible side chain, as an H atom

Answer 21

Glycine

Question 22

have aliphatic hydrocarbon atoms

Answer 22

Alanine, valine, leucine, and isoleucine

Question 23

has a thioether side chain that resembles an n-butyl
group in many of its physical properties

Answer 23

Methionine

Question 24

cyclic pyrrolidine side group.

Answer 24

Proline

Question 25

it contains aromatic side groups

Answer 25

phenylalanine and tryptophan

Question 26

What does uncharged polar side chains have?

Answer 26

hydroxyl, amide, thiol groups

Question 27

What are the six amino acids classified as uncharged polar side chains

Answer 27

STATGC Serine, Threonine, Asparagine, Glutamine, Tyrosine, Cysteine

Question 28

bear hydroxylic R groups of different sizes

Answer 28

Serine and Threonine

Question 29

amide-bearing side chains of different sizes

Answer 29

Asparagine and Glutamine

Question 30

has a phenolic group

Answer 30

Tyrosine

Question 31

unique among the 20 amino acids in that it has a thiol group that can form a disulfide bond with another cysteine through the oxidation of the two thiol groups

Answer 31

Cysteine

Question 32

how does disulfide bonds formed?

Answer 32

two thiol groups are oxidize

Question 33

The side chains of the acidic amino acids, aspartic acid and glutamic acid, are negatively charged above pH 3; in their ionized state, they are often referred to _________ and ______- . Asparagine and glutamine are, respectively, the amides of aspartic acid and glutamic acid

Answer 33

aspartate and glutamate

Question 34

what are the essential amino acids?

Answer 34

ILVLMPTT Isoleucine, Leucine, Valine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan

Question 35

Nonessential amino acids

Answer 35

AAACCGGGPST Alanine, Arginine, Aspartic Acid, Cysteine, Cystine, Glutamic acid, Glutamine, Glycine, Proline, Serine, Tyrosine

Question 36

Arginine, Cysteine and Glutamine, along with Taurine may be considered conditionally essential. Why?

Answer 36

Their requirements are increased during periods of catabolic stress.

Question 37

Disulfide bonds are one of the strongest naturally-occurring bonds in nature. Disulfide bonds link together two sulfur atoms attached to ________ amino acids within the polypeptide chains.

Answer 37

cysteine

Question 37

Disulfide bond formation involves a reaction between the sulfhydryl (SH) side chains of two cysteine residues

Answer 37

an S− anion from one sulfhydryl group acts as a nucleophile, attacking the side chain of a second cysteine to create a disulfide bond, and in the process releases electrons for transfer

Question 38

Configuration and combination of proteins is several by several factors

Answer 38

1. h-bonding (helical structure or pleated sheet) 2. disulfide bonds 3. salt bridges 4. hydrophobic and hydrophilic tendencies

Question 39

proteins are bonds between oppositely charged residues that are sufficiently close to each other to experience electrostatic attraction

Answer 39

Salt bridges

Question 40

amino acid sequence of the protein

Answer 40

primary structure

Question 41

h-bonds in the peptide chain backbone; a-helix, b -sheets

Answer 41

secondary structure

Question 42

non-covalent interactions between the r groups within the protein

Answer 42

tertiary

Question 43

interaction between 2 polypeptide chains

Answer 43

quaternary sturtcure

Question 44

widely used in biochemical literature

Answer 44

three-letter abbreviations

Question 44

often used when comparing the amino acid sequences of several protein properties

Answer 44

one-letter symbol

Question 45

proteins turn like a spiral

Answer 45

a-helix

Question 46

proteins fold back on itself as in a ribbon

Answer 46

B-pleated sheet

Question 47

2 types of b sheets

Answer 47

anti-parallel (opposite) parallel (same)

Question 48

class of shap; approximately spherical

Answer 48

Globular proteins

Question 49

parallel along a single axis (classes of shape)

Answer 49

Fibrous proteins

Question 50

Structure of proteins - made up of amino acids joined together by peptide bonds

Answer 50

simple

Question 51

- attached by covalent bonding or other intecations

Answer 51

cofactors and prosthetic groups

Question 52

composed of more that one subunit

Answer 52

oligomeric proteins

Question 53

prosthetic groups: metal ion conjugated protein :

Answer 53

metalloprotein

Question 54

prosthetic groups: polysaccharides conjugated protein :

Answer 54

glycoproteins

Question 56

process by which peptide bonds are broken under acidic conditions and happens during digestion of proteins

Answer 56

protein hydrolysis

Question 57

involves the disruption and possible destruction of both the secondary and tertiary structure

Answer 57

denaturation of proteins