Chp. 19 Amino Acids

Question 1

Storage protein examples?

Answer 1

Casein

Ferritin

Question 2

Amino acids, the molecular building blocks of proteins, have a central carbon atom called the α carbon, bonded to

Answer 2

an ammonium group (—NH3+) and a carboxylate group (—COO−)

a hydrogen atom and an R group or side chain in addition to the carboxylate and ammonium groups.

Question 3

a balance of positive and negative charge, which gives an overall zero charge (NET CHARGE = 0)

Answer 3

zwitterion

Question 4

hydrogen, alkyl, or aromatic R groups

Answer 4

nonpolar (hydrophobic) amino acids

Question 5

have R groups that interact with water, which makes them hydrophilic

Answer 5

polar amino acids

Question 6

contain hydroxyl (—OH), thiol (—SH), or amide (—CONH2) R groups

Answer 6

polar neutral amino acids

Question 7

contain a carboxylate (—COO−) R group.

Answer 7

polar acidic amino acids

Question 8

contain an ammonium(—NH3+) R group.

Answer 8

polar basic amino acids

Question 9

All are AAs are chiral except?

Answer 9

Glycine

Question 10

Nonpolar AA

Answer 10

Glycine
Alanine
Valine
Leucine
Isoleucine
Methionine
Phenylalanine (F)
Tryptophan (W)
Proline

Question 11

Polar AA

Answer 11

Serine
Threonine
Tyrosine (Y)
Cysteine
Asparagine
Glutamine (Q)

Question 12

Polar acidic AA

Answer 12

Aspartate

GLutamate

Question 13

Polar basic AA

Answer 13

Histidine
Lysine (K)
Arginine (R)

Question 14

an amide bond that forms when the —COO− group of one amino acid reacts with the —NH3+ group of the next amino acid

Answer 14

peptide bond

Question 15

the particular sequence of amino acids held together by peptide bonds

Answer 15

primary structure

Question 16

polypeptide of 50 or more amino acids with biological activity

Answer 16

protein

Question 17

9 Essential AA

Answer 17

Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine

Question 18

describes the structure that forms when amino acids form hydrogen bonds between the atoms in the backbone and atoms on the same or another peptide chain.

Answer 18

secondary structure

Question 19

Common secondary structure?

Answer 19

Alpha helix

Beta pleaded sheet

Question 20

hydrogen bonds form between the oxygen of the C=O groups and the hydrogen of N—H groups of the amide bonds

Answer 20

α helix

R-group is “pointed out”

Question 21

hydrogen bonds form between the carbonyl oxygen atoms and hydrogen atoms in the amide groups bending the polypeptide chain into a sheet

Answer 21

β-pleated sheet

Question 22

three polypeptide chains are woven together

hydrogen bonds hold the chains together, giving the polypeptide the added strength typical of collagen, connective tissue, skin, tendons, and cartilage

Answer 22

triple helix

Question 23

overall three-dimensional shape formed by the interactions and repulsions of amino acid residues in different parts of the chain

Answer 23

tertiary structure

Question 24

5 stabilizing interactions for tertiary structures…

Answer 24

Hydrophobic interactions
Hydrophilic interactions
Salt bridges
HYdrogen bonds
Disulfide bonds

Question 25

ionic attractions between ionized Rgroups of polar basic and polar acidic amino acids

Answer 25

Salt bridges

Question 26

covalent bonds that form between the —SH groups of cysteine residues in a polypeptide chain

Answer 26

Disulfide bonds

Question 27

Biologically active proteins with two or more polypeptide chains or subunits have a

Answer 27

quaternary structure.

Question 28

occurs when the interactions that stabilize secondary, tertiary, or quaternary structures are disrupted, which destroys the shape and renders the protein biologically inactive

Answer 28

Denaturation

Question 29

occurs in the stomach when enzymes catalyze the hydrolysis of proteins to give amino acids.
breaks up the primary structure by breaking the covalent peptide bonds that link the amino acids

Answer 29

Hydrolysis

Question 30

The loss of secondary and tertiary structures in a protein occurs when conditions change, such as

Answer 30

increasing the temperature.

making the pH very acidic or basic.

adding certain organic compounds or heavy metal ions.

adding mechanical agitation.

Question 31

Proteins are denatured when heated above 50°C. The heat

Answer 31

disrupts the hydrogen bonds and hydrophobic interactions among nonpolar residues

does not change the nutritional value of proteins but make them more digestible.

Question 32

Proteins can be denatured by changing the pH, which

Answer 32

breaks hydrogen bonds.

disrupts ionic bonds and salt bridges.

Question 33

Organic compounds such as ethanol and isopropyl alcohol act as disinfectants by

Answer 33

exchanging the bacterial protein’s hydrogen bonds to water with their own.

disrupting the side chain intramolecular hydrogen bonding.

Question 34

Heavy metal ions such as Ag+, Pb2+, and Hg2+ denature proteins by

Answer 34

forming bonds with ionic residues or reacting with disulfide —S—S— bonds

Question 35

mechanical agitation to denature proteins.

Answer 35

stretches the polypeptide chains until the stabilizing interactions are disrupted