Question

In 1964, Nirenberg and Leder used the triplet-binding assay to determine specific codon assignments. A complex of which of the following components was trapped in the nitrocellulose filter?

A) Charged tRNAs and ribosomes
B) mRNA and ribosomes
C) DNA and ribosomes
D) Uncharged tRNAs and ribosomes

Answer 1

In Nirenberg and Leder's triplet-binding assay, the complex trapped in the nitrocellulose filter consisted of Charged tRNAs and Ribosomes.

Step-by-step explanation:

In 1964, Marshall Nirenberg and Philip Leder utilized the triplet-binding assay to decipher specific codon assignments. This revolutionary method involved creating a complex that was trapped in a nitrocellulose filter during their experiments.

They mixed amino acid-bound tRNAs with isolated ribosomes and synthetic triplet nucleotides. Since previous experiments showed that synthetic triplets would bind to ribosomes, they hypothesized that these triplet-bound ribosomes would, in turn, bind specific amino acid-bound tRNAs matching the codons. When these complexes—composed of synthetic triplet codons, ribosomes, and charged tRNAs—were placed over the filter, the unbound components would pass through, leaving the bound complexes on the filter. This allowed Nirenberg and Leder to identify which amino acid was associated with each codon.

Therefore, the specific components that were trapped in the nitrocellulose filter were Complex of Charged tRNAs and Ribosomes (Answer A).

Answer 2

In 1964, Nirenberg and Leder used the triplet-binding assay to decipher codon assignments, which led to the trapping of complexes of charged tRNAs and ribosomes in a nitrocellulose filter, revealing the corresponding amino acids encoded by specific triplets.

Step-by-step explanation:

In 1964, Marshall Nirenberg and Philip Leder elucidated specific codon assignments using the triplet-binding assay. Their sophisticated experiment involved the interaction among synthetic ribonucleotide triplets, ribosomes, and amino acid-bound tRNAs (charged tRNAs). Aminoacyl-tRNAs when combined with synthetic triplets would bind specifically to ribosomes if the codon and anticodon matched appropriately.

This setup was placed over a nitrocellulose filter, which allowed certain components to pass through while retaining larger complexes. Since free aminoacyl-tRNAs passed through but ribosomes by themselves did not, the hypothesis was that when ribosomes bound to triplet codons and in turn bound to an appropriate charged tRNA, this larger complex would be trapped by the filter. The filter thus retained complexes of charged tRNAs together with ribosomes while unbound components passed through, allowing researchers to determine which amino acid was associated with which codon.

Through their pioneering research, Nirenberg and Leder were able to gain significant insight into the genetic code. This investigative technique became crucial in the field of molecular biology for its role in confirming which specific triplets coded for which amino acids, leading to the full deciphering of the genetic code.

The correct answer to the question of which complex was trapped by the nitrocellulose filter in Nirenberg and Leder's experiment is A) Charged tRNAs and ribosomes.