Question

Aptamers are

• A. Stereoisotopes of amino acids
• B. Single-stranded oligonucleotides that fold into defined architectures and bind to targets such as proteins
• C. Molecules formed by combination of nucleotide bases and carbohydrates
• D. The molecules used to treat bone tumor

Hint:

Aptamers are generated using the SELEX method. They offer advantages over antibodies, including low immunogenicity, thermal stability, and simple in vitro synthesis.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Aptamers are functional biomolecules engineered to bind specifically to target molecules.
They are often called "chemical antibodies" because they mimic the high affinity and selectivity of antibodies but are generated through in vitro chemical synthesis.

Step 2: Detailed Explanation:
Aptamers consist of short, single-stranded nucleic acid sequences (either DNA or RNA, typically 20 to 100 nucleotides in length).
Unlike genomic DNA, which is double-stranded and adopts a linear helical path, single-stranded oligonucleotides can fold into complex three-dimensional structures.
These folded shapes are determined by their nucleotide sequences, which form intramolecular base pairs, loops, hairpins, and pseudoknots.
The 3D surface of the folded aptamer complements the shape of a target molecule, allowing binding via non-covalent interactions (such as hydrogen bonding, electrostatic forces, and van der Waals interactions).
They are isolated from vast combinatorial libraries using an in vitro selection process known as SELEX (Systematic Evolution of Ligands by Exponential Enrichment).
Their targets can range from small ions and organic molecules to complex proteins and entire cells.

Step 3: Final Answer:
Aptamers are single-stranded oligonucleotides that fold into defined architectures and bind to targets such as proteins.