Proteinogenic amino acids: classification, examples, peptide bond.

What are proteinogenic amino acids?

Amino acids that are used in protein synthesis and encoded by the genetic code.

How many proteinogenic amino acids exist?

20 standard amino acids.

How are amino acids classified based on polarity?

Non-polar (Hydrophobic): Gly, Ala, Val, Leu, Ile, Met, Phe, Trp, Pro | Polar (Uncharged): Ser, Thr, Asn, Gln, Tyr, Cys | Polar (Charged): Acidic (-): Asp, Glu | Basic (+): Lys, Arg, His

Which amino acids are non-polar (hydrophobic)?

Glycine (Gly), Alanine (Ala), Valine (Val), Leucine (Leu), Isoleucine (Ile), Methionine (Met), Phenylalanine (Phe), Tryptophan (Trp), Proline (Pro)

Which amino acids are polar and uncharged?

Serine (Ser), Threonine (Thr), Asparagine (Asn), Glutamine (Gln), Tyrosine (Tyr), Cysteine (Cys)

Which amino acids are acidic (negatively charged)?

Aspartic acid (Asp), Glutamic acid (Glu)

Which amino acids are basic (positively charged)?

Lysine (Lys), Arginine (Arg), Histidine (His)

Which amino acids are essential?

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

Which amino acids contain sulfur?

Cysteine (Cys) & Methionine (Met)

What are the aromatic amino acids?

Phenylalanine (Phe), Tyrosine (Tyr), Tryptophan (Trp)

What is the only cyclic amino acid?

Proline (Pro)

What is a peptide bond?

A covalent bond formed between two amino acids through a condensation reaction.

Which functional groups participate in peptide bond formation?

The carboxyl (-COOH) group of one amino acid and the amino (-NH₂) group of another.

What type of reaction forms a peptide bond?

Condensation (dehydration) reaction, where water (H₂O) is removed.

What is the structure of a peptide bond?

-CO-NH- (Between the carbonyl carbon of one amino acid and the nitrogen of another).

Why is the peptide bond rigid and planar?

Due to resonance, it has partial double-bond character, making it rigid and planar.

What is the process of breaking a peptide bond?

Hydrolysis, which requires water and is catalyzed by enzymes like proteases.