Amino Acids Flashcards
What functional groups are present in amino acids?
Amino group and carboxyl group bonded to the a-carbon
a portion of an amino acid that determines its identity
Side chain
-NH2 functional group
Amino group
-COOH functional group that disassociates to give the carboxylate anion, -coo-, and a hydrogen ion
Carboxyl group
molecules that differ from each other only in their configuration
Stereoisomers
What is the configuration of the vast majority of a-amino acids?
L-configuration at the a-carbon
What is the usual form of proline?
L form
What is the three-letter abbreviation and one-letter abbreviation of alanine?
Ala, A
What is the three-letter abbreviation and one-letter abbreviation of arginine?
Arg, R
What is the three-letter abbreviation and one-letter abbreviation of asparagine?
Asn, N
What is the three-letter abbreviation and one-letter abbreviation of aspartic acid?
Asp, D
What is the three-letter abbreviation and one-letter abbreviation of cysteine?
Cys, C
What is the three-letter abbreviation and one-letter abbreviation of glutamic acid?
Glu, E
What is the three-letter abbreviation and one-letter abbreviation of glutamine?
Gln, Q
What is the three-letter abbreviation and one-letter abbreviation of histidine?
His, H
What is the three-letter abbreviation and one-letter abbreviation of glycine?
Gly, G
What is the three-letter abbreviation and one-letter abbreviation of isoleucine?
Ile, I
What is the three-letter abbreviation and one-letter abbreviation of leucine?
Leu, L
What is the three-letter abbreviation and one-letter abbreviation of lysine?
Lys, K
What is the three-letter abbreviation and one-letter abbreviation of methionine?
Met, M
What is the three-letter abbreviation and one-letter abbreviation of phenylalanine?
Phe, F
What is the three-letter abbreviation and one-letter abbreviation of proline?
Pro, P
What is the three-letter abbreviation and one-letter abbreviation of serine?
Ser, S
What is the three-letter abbreviation and one-letter abbreviation of threonine?
Thr, T
What is the three-letter abbreviation and one-letter abbreviation of tryptophan?
Trp, W
What is the three-letter abbreviation and one-letter abbreviation of tyrosine?
Tyr, Y
What is the three-letter abbreviation and one-letter abbreviation of valine?
Val, V
What are the 9 nonpolar amino acids?
Glycine, alanine, valine, leucine, isoleucine, proline, phenylalanine, tryptophan, and methionine
Which amino acids contain aliphatic hydrocarbon group?
alanine, valine, leucine, isoleucine
Which amino acid has an aliphatic cyclic structure?
Proline
Which amino acid has a hydrocarbon group that is aromatic?
Phenylalanine
Which amino acid has a side chain that contains an aromatic indole ring?
Tryptophan
Which amino acid has a side chain that contains a sulfur atom addition to aliphatic hydrocarbon groupings?
Methionine
What are the 6 polar-neutral amino acids?
Serine, threonine, tyrosine, cysteine, glutamine, and asparagine
Which two amino acids have a polar group (-OH) bonded to aliphatic hydrocarbon groups?
Serine and threonine
Which amino acid has a hydroxyl group (phenol) that is bonded to an aromatic hydrocarbon group?
Tyrosine
Which amino acid has a polar side chain that contains a thiol group (SH)?
Cysteine
Which two amino acids contain amide groups in their side chains?
Glutamine and asaparagine
What are the two acidic amino acids?
glutamic acid and aspartic acid
_____ can lose a proton, forming carboxylate anions
carboxyl group
Side chains of acidic amino acids are _____ charged at _____ pH
negatively, neutral
the average pKa of a-carboxyl group
2.19
Greater acidity is due to _____
the electron-withdrawing inductive effect of the -NH3+ group
What is the pKa of secondary alkylammonium ion?
10.76
Average value of pKa of an a-NH3+ group
9.47
What are the 3 basic amino acids?
Histidine, lysine, arginine
Side chains of basic amino acids are _____ charged at _____ pH
positively, near neutral pH 7
Which amino acid has a side chain attached to an aliphatic hydrocarbon chain?
lysine
Which amino acid has a side chain that is a guanidino group bonded to an aliphatic hydrocarbon chain?
arginine
Side chains of arginine that is a considerably stronger base than an aliphatic amine
guanidine
Basicity of the guanidino group is attributed to _____
the large resonance stabilization of the protonated form relative to the neutral form
Side chain of histidine is a heterocyclic aromatic amine
Imidazole group
Ratio of uncharged to charged side chains at pH 7.0
10:1 because the pH is one unit higher than the pKa