Chapter 1-7 Notes: Biomolecules and Protein Structure (Flashcards)

A set of Question-and-Answer flashcards covering biomolecules, amino acid structure, and the four levels of protein structure, plus denaturation and structure-function relationships as discussed in the notes.

What are the main biomolecules discussed in Chapter 1?

Amino acids, carbohydrates, lipids, and nucleic acids.

What functional group makes an amino acid an amino acid?

The carboxylic acid group attached to the amino acid.

What term describes a chain of many amino acids linked by peptide bonds?

A polypeptide; when folded, it becomes a protein.

What is the primary structure of a protein?

The sequence (order) of amino acids in the protein.

What are the two main types of secondary structure in proteins?

Alpha helices and beta-pleated sheets, formed by backbone hydrogen bonds.

What is tertiary structure?

The fully folded three-dimensional shape of a single polypeptide.

What four interactions help stabilize a protein's tertiary structure?

Salt bridges, hydrogen bonds, hydrophobic interactions, and disulfide bridges (between cysteines).

What is a subunit in protein structure?

A tertiary unit that can join with others to form a quaternary structure; a subunit is a tertiary structure in its own right.

What is quaternary protein structure?

The assembly of two or more tertiary structure subunits into a larger functional protein (e.g., four-subunit hemoglobin).

What is denaturation?

Unfolding of a protein and loss of function, typically without breaking the primary sequence.

What conditions can denature proteins?

Temperature, changes in pH, organic solvents, detergents, heavy metals, and stress.

What is the relationship between protein structure and function?

A protein’s function is determined by its structure; disrupting structure (denaturation) disrupts function.

In an aqueous environment, where do hydrophobic and hydrophilic amino acids tend to be located?

Hydrophobic (nonpolar) residues tend to be inside the protein; hydrophilic (polar) residues tend to be on the exterior facing water.

What is the difference between a peptide and a polypeptide?

A peptide (bonds amino acids) is a short chain of amino acids; a polypeptide is a longer chain of amino acids.

What is a hydrogen bond in proteins?

A non-covalent attraction between a hydrogen attached to N or O and another electronegative atom (N or O) that helps stabilize secondary and higher structures.

What is a disulfide bridge?

A covalent bond between two cysteine residues formed by oxidation, helping to stabilize tertiary structure.

Give a common example of a protein with multiple subunits used to illustrate quaternary structure.

Hemoglobin, which has four subunits.

What happens to the primary sequence during denaturation?

Primary structure is typically preserved; denaturation mainly disrupts noncovalent interactions and 3D folding, not peptide bonds.

What is the effect of pH on protein denaturation as described in the notes?

Ionizable side chains can be altered by pH changes (pKa shifts), disrupting folding and denaturing the protein.