Question

structure determines function! proteins accomplish many cellular tasks such as facilitating chemical reactions, providing structure, and carrying information from one cell to another. how a protein chain coils up and folds determines its three - dimensional shape. its shape will, in turn, determine how it interacts with other molecules and thus performs its function in the cell. 5. fill in the following chart using what youve learned about the levels of protein structure. structure level bond(s) or interactions holding structure together brief description of molecule at this level number of polypeptides involved primary secondary tertiary quaternary 6. proteins carry out a variety of functions, and their function is critically dependent upon their structure and shape. enzymes are proteins that catalyze chemical reactions. what would happen to the structure and function of an enzyme that was exposed to high heat or a drastic change in ph? 7. hair is made of protein. when people use heat of chemicals to straighten their hair, hydrogen and disulfide bonds that give the hair strands their shape (curled) are broken and the hair is held in a new form (straight). a. what level(s) of protein structure listed in the table above would not be impacted by the hair straightening processes? b. why doesnt the hair stay straight forever after this kind of treatment?

Explanation:

1. Primary Structure:

• Bonds/Interactions: Peptide bonds. These are covalent bonds that link amino - acids together in a linear sequence to form a polypeptide chain.
• Molecule Description: A linear sequence of amino - acids.
• Number of Polypeptides: 1.

1. Secondary Structure:

• Bonds/Interactions: Hydrogen bonds between backbone atoms (N - H and C=O groups). These bonds cause the polypeptide chain to fold into regular patterns like alpha - helices and beta - sheets.
• Molecule Description: Local, regular folding patterns of the polypeptide chain.
• Number of Polypeptides: 1.

1. Tertiary Structure:

• Bonds/Interactions: Multiple types including hydrogen bonds, disulfide bridges (covalent bonds between cysteine residues), ionic bonds, and van der Waals forces. These interactions fold the secondary - structure elements into a three - dimensional shape.
• Molecule Description: The overall three - dimensional shape of a single polypeptide chain.
• Number of Polypeptides: 1.

1. Quaternary Structure:

• Bonds/Interactions: Similar to tertiary structure (hydrogen bonds, disulfide bridges, ionic bonds, van der Waals forces), but between different polypeptide chains.
• Molecule Description: The arrangement of multiple polypeptide chains (sub - units) into a multi - sub - unit complex.
• Number of Polypeptides: More than 1.

1. For an enzyme exposed to high heat or drastic pH change:

• High heat or drastic pH disrupts the non - covalent bonds (hydrogen bonds, ionic bonds, van der Waals forces) and in some cases, disulfide bridges in the enzyme's tertiary and secondary structures. This leads to denaturation, where the enzyme loses its three - dimensional shape. Since the function of an enzyme is highly dependent on its shape, its catalytic activity is lost as it can no longer bind to its substrate properly.

1. a. The primary structure of the protein in hair would not be impacted by hair - straightening processes. Heat and chemicals break hydrogen and disulfide bonds which are involved in secondary, tertiary, and quaternary structures, but the linear sequence of amino - acids (primary structure) remains intact.

b. Hair doesn't stay straight forever because the hydrogen and disulfide bonds that were broken during the straightening process can re - form over time. The hair proteins will tend to return to their original, more stable (curled) conformation based on the natural tendencies of the amino - acid sequence and the environmental conditions.

Answer:

Structure Level	Bond(s) or Interactions holding structure together	Brief description of molecule at this level	Number of Polypeptides involved
Secondary	Hydrogen bonds between backbone atoms	Local, regular folding patterns	1
Tertiary	Hydrogen bonds, disulfide bridges, ionic bonds, van der Waals forces	Overall three - dimensional shape of a single polypeptide	1
Quaternary	Hydrogen bonds, disulfide bridges, ionic bonds, van der Waals forces between different polypeptide chains	Arrangement of multiple polypeptide chains into a multi - sub - unit complex	> 1

1. Structure: Denatured (loses three - dimensional shape). Function: Catalytic activity lost.
2. a. Primary structure.

b. Hydrogen and disulfide bonds can re - form over time.