Final answer:
A-helices in proteins are stabilized by hydrogen bonding and are affected by the amino acid sequence. They are an extended conformation of the polypeptide chain.
Step-by-step explanation:
The statements that are TRUE of a-helices are:
B. Stabilized by H bonds between -NH and-Co groups Found in globular proteins
C. Affected by amino acid sequence
D. An extended conformation of the polypeptide chain
The amino acid sequence, or primary structure, of a protein determines its secondary structure, including the presence of a-helices. A-helices are stabilized by intrachain hydrogen bonding between the carbonyl oxygen atom of one amino acid and the amide hydrogen atom four amino acids up the chain. Therefore, these statements accurately describe a-helices.