Week 26 / Amino Acids Flashcards
Q: What are proteins and many other important biomolecules made from?
A: Amino acids.
Q: What are the amino acids most commonly found in nature called?
A: α-amino acids (alpha-amino acids).
Q: Which amino acid is the only achiral member of the 20 common amino acids?
why?
A: Glycine.
This is because glycine has a hydrogen atom as its side chain
Q: In which optical form do the 19 chiral amino acids most commonly exist?
A: The L-optical form.
Q: Why are amino acids considered amphoteric molecules?
A: Because they contain both an acidic group (carboxyl group, -COOH) and a basic group (amino group, -NH2).
Q: What does the term “amphoteric” mean in relation to amino acids?
A: It means they can act as both an acid (donating a proton) and a base (accepting a proton).
Q: Which amino acids have nonpolar, aliphatic R groups?
A: Glycine, Alanine, Proline, Valine, Leucine, Isoleucine, and Methionine.
Q: Which amino acids have polar, uncharged R groups?
[STAGC]
A: Serine, Threonine, Cysteine, Asparagine, and Glutamine.
Q: Which amino acids have aromatic R groups?
[TPT]
A: Phenylalanine, Tyrosine, and Tryptophan.
Q: What property of peptide bonds provides them with significant stability?
A: Peptide bonds exhibit strong resonance, resulting in delocalization of electrons between the carbonyl oxygen and the amide nitrogen.
Q: How much does resonance energy stabilize peptide bonds?
A: The delocalization energy stabilizes peptide bonds by 75-90 kJ/mol.
Q: Why do peptides prefer a planar conformation?
A: The resonance in peptide bonds gives them partial double-bond character, restricting rotation and favoring a planar, trans (anti/Z) conformation.
Q: Where does the naming of a peptide or protein start?
A: At the N-terminal amino acid (the amino acid with a free amino group, -NH2).
Q: How many chains of amino acids make up insulin?
A: Two chains of amino acids.
Q: How are the two chains of insulin linked?
A: By disulfide bonds.
Q: How many commonly occurring amino acids are there?
A: 20.
Q: What type of bond links amino acids together?
A: Peptide bonds, forming amides.
Q: What do we call longer chains of amino acids?
A: Polypeptides, and the largest chains are proteins.
Q: What are short chains of amino acids called?
A: Oligopeptides.
Q: When naming sequences of amino acids, where do we start?
A: From the amino terminus (N-terminus).
Q: Besides peptide bonds, how else can amino acids be linked?
A: Via disulfide bonds.
Whats a dipeptide ?
Whats a Oligopeptides?
a protein that contains two amino acids
a protein contain 2-10 amino acids
Whats the only amino acid linked by disulphide bond?
Cysteines
What does Glutathione form?
What are they linked by?
Forms disulphide in presence of oxidizing agents.
via sidechain Glu acid
