Chapter 19 Flashcards

Amino acid

The molecular building blocks of proteins, consisting of a central carbon atom, an ammonium group, a carboxylate group, a hydrogen atom, and a variable R group.

Peptide bond

An amide bond that forms between the amino group of one amino acid and the carboxyl group of another, linking amino acids to form a peptide.

Dipeptide

A peptide formed from two amino acids.

Tripeptide

A peptide formed from three amino acids.

Polypeptide

A chain of amino acids linked by peptide bonds, with 50 or more amino acids typically forming a functional protein.

Primary structure

The unique sequence of amino acids in a polypeptide chain that determines its specific characteristics.

Secondary structure

The local folded structures that form within a polypeptide due to interactions between atoms in the backbone; commonly includes alpha helices and beta-pleated sheets.

Tertiary structure

The overall three-dimensional shape of a single polypeptide chain, determined by interactions among R groups.

Quaternary structure

The arrangement and interaction of multiple polypeptide subunits in a protein, resulting in a functional protein complex.

Hydrophobic interaction

Forces that occur between nonpolar side chains of amino acids, driving them to the interior of the protein to avoid water.

Hydrophilic interaction

Interactions occurring between the exterior aqueous environment and the polar side chains of amino acids, keeping them on the surface of proteins.

Disulfide bond

A covalent bond formed between the sulfur atoms of cysteine residues, providing additional stability to protein structure.

Essential amino acids

A group of nine amino acids that cannot be synthesized by the body and must be obtained through diet.

Denaturation

The process in which a protein loses its native structure and function due to the disruption of stabilizing interactions.

Hydrolysis

A chemical reaction that breaks peptide bonds, resulting in the cleavage of proteins into their amino acid components.

Sickle-cell anemia

A genetic disorder caused by a mutation in hemoglobin, leading to abnormally shaped red blood cells that interfere with oxygen transport.

What are amino acids?

They are the molecular building blocks of proteins.

How is a peptide bond formed?

By joining the amino group of one amino acid with the carboxyl group of another.

What is a dipeptide?

A peptide that consists of two amino acids.

What characterizes a tripeptide?

It is formed from three amino acids.

What defines a polypeptide?

A chain of 50 or more amino acids linked together.

What is the primary structure of a protein?

The unique sequence of amino acids in a polypeptide chain.

What structures are included in secondary protein structure?

Commonly alpha helices and beta-pleated sheets.

What determines the tertiary structure of a protein?

The overall 3D shape determined by interactions among R groups.

What is quaternary structure?

The arrangement and interaction of multiple polypeptide subunits.

What happens during protein denaturation?

The protein loses its native structure and function.