During a genome project, which peptide sequence listed is most likely to represent the transmembrane segment due to its composition?

The peptide sequence that most likely represents a transmembrane segment is the one composed predominantly of hydrophobic amino acids, which facilitate the integration of the peptide into the lipid bilayer of a cell membrane.

In the correct answer, the sequence features a high proportion of hydrophobic residues such as leucine, valine, isoleucine, phenylalanine, and methionine. These amino acids are non-polar and have side chains that do not interact favorably with water, making them suitable for residing within the hydrophobic environment of the membrane. Their abundance in the sequence suggests that this peptide segment is likely involved in spanning the membrane, a characteristic feature of transmembrane proteins.

In contrast, the other sequences contain a higher representation of polar or charged amino acids such as aspartate, serine, and lysine, which are generally more hydrophilic. These residues are less likely to be found in transmembrane segments, as they would prefer to be in an aqueous environment rather than embedded within the lipid bilayer. Therefore, the sequence with the highest concentration of hydrophobic amino acids is most indicative of a transmembrane segment.