Question

Francis Crick proposed the adaptor hypothesis for the function of tRNA. Why did he choose that description?

Short answer

Short Answer: Francis Crick's adaptor hypothesis proposes that tRNA functions as an adaptor molecule in protein synthesis, linking the information in mRNA to the corresponding amino acid. The term "adaptor" is fitting because tRNA essentially acts as a bridge between the mRNA and the amino acids, decoding the genetic information in mRNA into the language of proteins by matching its anticodon to the mRNA codon and delivering the corresponding amino acid to the growing polypeptide chain.

Step-by-step solution

Understanding the adaptor hypothesis

The adaptor hypothesis is a concept introduced by Francis Crick to explain the role of tRNA in the process of protein synthesis. tRNA, or transfer RNA, is a type of RNA molecule that helps in decoding the genetic information present in mRNA (messenger RNA) into amino acids, which are the building blocks of proteins. The hypothesis states that tRNA functions as an adaptor molecule, linking the information in mRNA to the corresponding amino acid during protein synthesis.

Understanding tRNA structure and function

tRNA has a unique three-dimensional structure with an acceptor stem at one end and an anticodon loop at the other end. The acceptor stem is where an amino acid is attached, whereas the anticodon loop contains a triplet of bases called the anticodon that is complementary to the codon on the mRNA. Thus, tRNA has a specific role in protein synthesis: to read the genetic code on mRNA and, by matching the anticodon to the mRNA codon, deliver the corresponding amino acid to the growing polypeptide chain.

Explaining the choice of the term "adaptor"

In the context of protein synthesis, Francis Crick chose the term "adaptor" because tRNA essentially acts as an adaptor, or a bridge, between the mRNA and the amino acids during protein synthesis. tRNA effectively "adapts" the genetic information in mRNA into the language of proteins by ensuring that the correct amino acid is incorporated at the right position within the growing protein chain. This crucial role that tRNA plays in protein synthesis makes the term "adaptor" quite appropriate and fitting for describing its function.

Key concepts

tRNA function

Transfer RNA, or tRNA, plays a crucial role in translating genetic information into proteins. Each tRNA molecule has a specific structure that allows it to perform its function efficiently. This structure includes an acceptor stem, where an amino acid is attached, and an anticodon loop, which contains a sequence of three bases. These bases are complementary to a specific codon on the messenger RNA (mRNA). By this mechanism, tRNA acts as a key player in the protein synthesis process, effectively reading the genetic code.

• tRNA attaches to specific amino acids and delivers them to the mRNA.
• The anticodon on tRNA pairs with the mRNA codon, ensuring the correct amino acid sequence.
• tRNA's function is vital for the correct interpretation and execution of genetic instructions.

protein synthesis

Protein synthesis is the biological process of building proteins based on the genetic instructions carried by mRNA. This process takes place in two main stages: transcription and translation. Transcription is the first step where a specific segment of DNA is copied into mRNA. This mRNA then serves as a template for translation, which is where tRNA comes into play.

During translation, ribosomes facilitate the binding of tRNA to mRNA. Each tRNA molecule brings a specific amino acid that matches the codon sequence on the mRNA. The ribosome moves along the mRNA strand, adding the corresponding amino acids to form a polypeptide chain. Over time, this chain folds and forms a functional protein.

• Translation is the "reading" phase of protein synthesis where tRNA matches codons and anticodons.
• Ribosomes act as the site of protein synthesis, facilitating the addition of amino acids.
• The resulting peptide chain folds into a specific structure needed for protein function.

Crick's contribution

Francis Crick's contribution to molecular biology is monumental. Among his many achievements, the proposal of the "adaptor hypothesis" stands out as a significant milestone. Crick introduced this term to describe the role of tRNA in protein synthesis.

Crick's insight was based on the idea that there must be some molecule responsible for translating the genetic code from nucleic acids into proteins. He envisioned tRNA as being that molecule. By acting as a bridge between mRNA and amino acids, tRNA facilitates the assembly of proteins according to the genetic blueprint.

• The "adaptor hypothesis" described how tRNA "adapts" genetic instructions.
• Crick's hypothesis helped clarify the intermediary role tRNA plays in linking nucleic acids and proteins.
• This concept was essential in advancing our understanding of genetic translation and protein assembly.