Question

Proteins vary widely in structure, whereas nucleic acids have rather uniform structures. How do you account for this major difference?

Short answer

The major difference is due to the variety in the building blocks of proteins (20 types of amino acids) vs nucleic acids (4 types of nucleotides). The diverse combination and folding of amino acids in proteins lead to varied structures. In contrast, nucleic acids, despite having different nucleotide sequences, maintain a consistent structure.

Step-by-step solution

Understanding Proteins

Proteins are made up of 20 different types of amino acids. These amino acids can be arranged in a variety of sequences, leading to a vast array of possible proteins each with its unique structure, function, and properties. Furthermore, the folding of these sequences into complex 3D structures adds another level of variety.

Understanding Nucleic Acids

Nucleic acids, on the other hand, are composed only of four types of nucleotides: adenine, guanine, cytosine, and thymine (or uracil, in case of RNA). These nucleotides form two types of nucleic acids: DNA and RNA. The nucleotides in DNA and RNA form sequences, but unlike proteins, the structure of nucleic acids is similar regardless of the sequence. It can exist as a double helix (in the case of DNA) or a single strand (typically for RNA). The structure of nucleic acids is more concerned with the information they carry, rather than their structural diversity.

Comparison

So, the diversity in the number and type of building blocks (amino acids) in proteins accounts for their wide variety in structure. On the other hand, the limited types of nucleotides and consistent bonding pattern in nucleic acids result in a more uniform structure.