Organic 25: Amino Acids, Peptides, & Proteins

Question 1

Amino acids

Answer 1

carboxylic acids that contain an amine function

Question 2

Peptide bond

Answer 2

an amide bond between the carboxylic acid function of 1 amino acid and the amino nitrogen of another forms this type of bond

Question 3

Dipeptide

Answer 3

molecule consisting of 2 amino acids joined by a peptide bond

Question 4

Tripeptide

Answer 4

molecule consisting of 3 amino acids joined by 2 peptide bonds

Question 5

Tetrapeptide

Answer 5

molecule consisting of 4 amino acids joined by 3 peptide bonds

Question 6

Polypeptides

Answer 6

peptides with more then 30-50 amino acids

Question 7

Proteins

Answer 7

polypeptides that have some biological function

Question 8

Standard amino acids

Answer 8

group of 20 amino acids coded for in DNA-directed protein synthesis; all are alpha-amino acids; all but one contain a primary amino function

Question 9

Essential amino acids

Answer 9

amino acids that must be obtained from one’s diet

Question 10

Amino Acid Racemization (AAR)

Answer 10

novel technique for dating archaeological samples; based on the stereochemistry of amino acids

Question 11

Zwitterion

Answer 11

the form in which neutral amino acids actually exist; the amino group is in its protonated form and the carboxyl group is present as a carboxylate

Question 12

Isoelectric (isoionic) point

Answer 12

pH at which the amino acid has no net charge

Question 13

N (amino) terminus

Answer 13

the left end of the peptide, contains the amino group

Question 14

C (carboxyl) terminus

Answer 14

the right end of the peptide, containing the carboxyl group

Question 15

Amino acid residues

Answer 15

individual amino acid components of peptides

Question 16

Primary structure

Answer 16

amino acid sequence plus any disulfide links

Question 17

Peptidases

Answer 17

the enzymes that catalyze the hydrolysis of peptide bonds

Question 18

Peptide map

Answer 18

the collection of sequenced fragments of amino acids for a particular substance

Question 19

Edman Degradation

Answer 19

method for determining the N-terminal amino acid of a peptide or protein; involves treating the material with phenyl isothiocyanate (C6H5N=C=S), cleaving with acid, then identifying the phenylthiohydantoin (PTH derivative) produced

Question 20

Secondary structure

Answer 20

conformational relationship of nearest neighbor amino acids with respect to each other

Question 21

Alpha helix, Beta sheet

Answer 21

secondary structures of proteins

Question 22

Random coils

Answer 22

a portion of a protein that lacks an ordered secondary structure

Question 23

Tertiary structure

Answer 23

the way a protein chain is folded; affects both its physical properties and its biological function

Question 24

Fibrous

Answer 24

protein bundles of elongated filaments of protein chains; insoluble in water

Question 25

Globular

Answer 25

spherical proteins; either soluble or form colloidal dispersions in water

Question 26

Hydrophobic effect

Answer 26

the excluding of nonpolar molecules from water

Question 27

Enzyme

Answer 27

a protein that catalyzes a chemical reaction in a living system

Question 28

Active site

Answer 28

region of an enzyme at which a substrate is bound

Question 29

Cofactors

Answer 29

a molecule that acts in combination with an enzyme to bring about a reaction; may either be a coenzyme or a prosthetic group

Question 30

Coenzyme

Answer 30

cofactors that are organic molecules and not covalently bonded to the enzyme

Question 31

Prosthetic group

Answer 31

cofactors that are organic molecules and ARE covalently bonded to the enzyme

Question 32

Quaternary structure

Answer 32

description of the way in which 2 or more protein chains, not connected by chemical bonds, are organized in a larger protein