General Biochemistry: Part I - Amino Acids and Peptide Bonds

Flashcards to review key concepts about amino acids, their structure, properties, and peptide bonds.

What is the role of amino acids in biochemistry?

The building blocks of proteins, which are essential for various biochemical functions.

Besides being building blocks, what is another function of amino acids?

They can be metabolized to provide energy.

What other biomolecules are amino acids precursors to?

They are precursors of important biomolecules like glucose, neurotransmitters, and hormones.

What are the basic chemical features of an amino acid?

A central carbon atom (α carbon), a carboxylic acid group, an amino group, and a side chain (R).

How many different amino acids are found as building blocks in virtually all proteins?

About twenty

What are 'true amino acids' in biochemistry?

Amino acids that have a genetic code in our DNA

What is a zwitterion?

A molecule with both positive and negative charges but is overall neutral.

What is the isoelectric point (pI)?

The pH at which a molecule exists as a zwitterion.

In eukaryotic organisms, are proteins made from D or L amino acids?

L form

What should a biochemistry student know regarding the chemistry of amino acids?

Name, three-letter abbreviation, one-letter symbol, and structure.

How are amino acids organized based on the physicochemical properties of their side chains?

Non-polar (hydrophobic), polar uncharged, acidic (polar charged), and basic (polar charged).

Give examples of Nonpolar, hydrophobic amino acids

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

Give examples of Polar, uncharged amino acids

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

Give examples of Polar, charged, acidic amino acids

Aspartic acid (Asp), Glutamic acid (Glu)

Give examples of Polar, charged, basic amino acids

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

What is the fundamental chemical bond between two amino acids?

Amide bond, also known as the peptide bond.

What is a dipeptide?

Two amino acids linked

What is a polypeptide?

Many (up to one hundred) amino acids linked.

What is a protein (in terms of amino acid count)?

More than one hundred amino acids linked.

What are 'residues'?

Individual amino acids within a peptide or protein.

What is the 'N-terminal' of a peptide or protein?

The amino acid with the free amino group

What is the 'C-terminal' of a peptide or protein?

The amino acid with the free carboxylic acid group

What is the main covalent bond between amino acids in a protein structure?

The peptide bond.

How is a disulfide bridge formed?

Two thiol groups from cysteines reacting (oxidizing) to form a disulfide bond.

Apart from the twenty standard amino acids, what is the 21st amino acid that some proteins may contain?

Selenocysteine (Sec; U).