Codon and on and on
This type of short synthetic RNA was paired with radiolabeled aminoacyl‑tRNAs in filter binding assays to reveal which codons corresponded to which amino acids.
What are homopolymers (e.g., poly‑U, poly‑A)?
This position of the codon–anticodon interaction is where wobble pairing occurs, allowing a single tRNA to recognize multiple codons.
What is the 5′ anticodon position (pairing with the 3′ codon base)?
These enzymes are responsible for attaching the correct amino acid to its corresponding tRNA, a process known as “charging.”
What are aminoacyl‑tRNA synthetases?
In bacteria, this special tRNA carries the very first amino acid and recognizes the start codon during initiation.
What is fMet‑tRNA
This elongation factor brings aminoacyl‑tRNAs to the A‑site and hydrolyzes GTP only after correct codon recognition.
What is EF‑Tu (or eEF1A in eukaryotes)?
In a filter binding assay, this macromolecular complex traps the correct aminoacyl‑tRNA on a nitrocellulose filter when the matching codon is present.
What is the ribosome?
This modified nucleotide, often found at the wobble position of tRNAs, can pair with U, C, or A, dramatically expanding decoding flexibility.
What is inosine?
Many tRNA synthetases contain a separate “editing site” that removes incorrectly attached amino acids, giving them this nickname related to accuracy.
What is a proofreading (or editing) function?
This three‑letter bacterial initiation factor helps the initiator tRNA bind to the P‑site of the small ribosomal subunit.
What is IF‑2?
During elongation, the tRNA carrying the growing peptide chain moves from this site to this site after translocation.
What are the A‑site to the P‑site?
These short, chemically synthesized RNA sequences were essential in filter binding assays because they allowed precise testing of individual codons.
What are trinucleotides? What are anticodons?
Wobble base pairing helps explain why organisms need fewer of these molecules than the total number of codons.
What are tRNAs?
Aminoacyl‑tRNA synthetases fall into these two structural classes, each with distinct active‑site architectures and tRNA‑binding modes.
What are Class I and Class II synthetases?
This purine‑rich sequence in bacterial mRNA helps position the start codon by base‑pairing with the 16S rRNA.
What is the Shine–Dalgarno sequence?
This specific region of the large ribosomal subunit undergoes a conformational shift during elongation to position substrates for peptide bond formation.
What is the peptidyl transferase center?
The presence of this label on aminoacyl‑tRNAs allowed researchers to detect which tRNA remained bound after filtration.
What is a radioactive isotope (e.g., 14C or 3H)?
In wobble rules, this base in the anticodon can pair with either A or G in the codon.
What is U?
These structural or sequence features on a tRNA allow its synthetase to recognize it among dozens of similar molecules.
What are identity elements (or identity determinants)?
In bacteria, this initiation factor hydrolyzes GTP to lock the initiator tRNA into the P‑site and trigger assembly of the full 70S ribosome.
What is IF‑2?
This ribosomal motion, driven by EF‑G, shifts the mRNA by exactly one codon.
What is translocation?
In filter binding assays, adding excess unlabeled tRNA reduces retention of the radiolabeled tRNA on the filter. This outcome demonstrates that codon recognition depends on this molecular feature of tRNAs.
What is anticodon specificity?
This anticodon base has the broadest wobble capacity, able to pair with U, C, or A in the codon.
What is inosine (I)?
Charging a tRNA with its amino acid consumes this high‑energy molecule, effectively costing the cell two high‑energy phosphate bonds.
What is ATP?
During bacterial initiation, this ribosomal subunit is the first to bind the mRNA, guided by base‑pairing to the Shine–Dalgarno sequence
What is the 30S subunit?
After translocation, the deacylated tRNA occupies this site before leaving the ribosome.
What is the E‑site?