An alpha-helix contains mainly amino acids with polar R-groups while Beta-pleated sheet mainly non-polar R-groups. TRUE/ FALSE?

Question

Structures of proteins (secondary or 3D protein structure) and its composition

Answer 1

False (I think)

Both alpha helices and beta pleated sheets have polar (hydrophilic) and non-polar(hydrophobic) R groups in about an equal amount. Since both are present in a globular protein and both have the same primary structure (amino acid chains)

Answer 2

False. Alpha-helices and beta-pleated sheets are two common types of secondary protein structure, which refers to the way that the polypeptide chain folds and interacts with itself to form a specific three-dimensional shape.

Alpha-helices are characterized by a helical structure that is held together by hydrogen bonds between the peptide bonds of the polypeptide chain. They tend to be formed by amino acids that have hydrophobic (non-polar) side chains, such as leucine, valine, and isoleucine.

Beta-pleated sheets are formed when the polypeptide chain folds back on itself and forms hydrogen bonds between the peptide bonds of adjacent strands. They tend to be formed by amino acids that have polar or charged side chains, such as aspartate, glutamate, and lysine.

Therefore, it is incorrect to say that alpha-helices contain mainly amino acids with polar R-groups and beta-pleated sheets contain mainly non-polar R-groups. Instead, the opposite is true: alpha-helices tend to be formed by amino acids with non-polar side chains, while beta-pleated sheets tend to be formed by amino acids with polar or charged side chains.

Answer 3

True. An alpha-helix contains mainly amino acids with polar R-groups, while a beta-pleated sheet contains mainly non-polar R-groups.

Answer 4

Alpha-helices are characterized by a helical structure that is held together by hydrogen bonds between the peptide bonds of the polypeptide chain. They tend to be formed by amino acids that have hydrophobic (non-polar) side chains, such as leucine, valine, and isoleucine.

Beta-pleated sheets are formed when the polypeptide chain folds back on itself and forms hydrogen bonds between the peptide bonds of adjacent strands. They tend to be formed by amino acids that have polar or charged side chains, such as aspartate, glutamate, and lysine.