Final answer:
Alpha helices are a smaller size that fits into the major groove of DNA, making option C) Smaller, DNA the correct answer. They are part of protein structures that interact with DNA during biological processes like transcription.
Step-by-step explanation:
The question relates to the compatibility of alpha helices and the structural grooves in DNA. Alpha helices are a structural motif in proteins. The correct answer to the student's question is that alpha helices are a smaller size to fit into the major groove of DNA. This means that the right choice is C) Smaller, DNA. The alpha helix is a common folding pattern in proteins, where the polypeptide backbone is coiled in a right-handed spiral. Each turn of this helix has 3.6 amino acid residues, and the R groups of these amino acids stick out from the helix, allowing for interactions with other molecules, including fitting into the major groove of DNA during processes such as transcription.
The double helical structure of DNA, often described as a twisted staircase, consists of two antiparallel strands forming a uniform diameter of 2 nm due to the complementary pairing between purine and pyrimidine bases. The major groove is a site where DNA-binding proteins commonly interact with the molecule, recognizing specific base sequences without unwinding the double helix and thereby regulating various biological processes.