What is the typical size range, in nucleotides, for a transfer RNA (tRNA) molecule?
tRNA molecules are typically between 73 and 93 nucleotides long.
Which RNA polymerase is responsible for the synthesis of tRNA molecules?
tRNA is synthesized by RNA Polymerase III (RNAP III).
What type of promoters does RNA Polymerase III use for tRNA synthesis?
RNA Polymerase III uses type 2 internal promoters for tRNA synthesis.
In the processing of tRNA, what modification does ‘D’ represent?
The letter ‘D’ represents the modified base dihydrouridine.
In tRNA and mRNA interactions, what modification does ‘I’ represent?
The letter ‘I’ represents the modified base inosine.
What modification in tRNA does the Greek letter Ψ (psi) represent?
The Greek letter Ψ (psi) represents the modified base pseudouridine.
How does splicing of tRNA introns occur if there is no consensus sequence for recognition?
Splicing depends on the recognition of a common secondary structure in the precursor tRNA molecule.
What enzyme is responsible for removing the 5’ leader sequence from a primary tRNA transcript?
The 5’ leader sequence is removed by RNase P.
What is the key difference between bacterial and eukaryotic RNase P?
Bacterial RNase P is a ribozyme, while eukaryotic RNase P is a nucleolar RNP enzyme.
After the 3’ trailer is removed, what sequence is added to the 3’ end of a tRNA molecule?
The sequence CCA is added to the 3’ end.
What enzyme catalyzes the addition of the CCA sequence to the 3’ end of tRNA?
The enzyme nucleotidyl transferase adds the CCA sequence.
What are the two primary functions of a tRNA molecule in translation?
To be linked to a specific amino acid and to recognize a corresponding codon in mRNA.
What is the name of the enzymes that attach amino acids to their corresponding tRNA molecules?
Aminoacyl-tRNA synthetases (ARS) attach amino acids to tRNAs.
The process of attaching an amino acid to a tRNA is known as _____ the tRNA.
charging
What is the name for the three-nucleotide sequence on a tRNA that base-pairs with a codon on mRNA?
The anticodon.
Where on the tRNA molecule does the amino acid attach?
The amino acid attaches to the free 2’ or 3’ hydroxyl group of the adenosine at the 3’ CCA end.
What is the first step in the tRNA charging reaction catalyzed by aminoacyl-tRNA synthetase?
The adenylation of the amino acid, where ATP is used and pyrophosphate (PPi) is released.
What happens in the second step of tRNA charging, after the amino acid has been adenylated?
The adenylylated amino acid is transferred to the 2’ or 3’ OH of the terminal adenosine on the tRNA, releasing AMP.
How many different aminoacyl-tRNA synthetases exist in a cell?
There are 20 different synthetases, one for each amino acid.
What part of the tRNA complex does the ribosome primarily recognize during translation?
The ribosome recognizes the tRNA molecule itself, not the amino acid it carries.
What phenomenon allows a single tRNA to recognize more than one codon for a specific amino acid?
Non-standard base pairing in the “wobble position”.
In the codon-anticodon interaction, which nucleotide position on the mRNA codon is the “wobble” position?
The third nucleotide (at the 3’ end) of the mRNA codon is the wobble position.
In the codon-anticodon interaction, which nucleotide position on the tRNA anticodon is the “wobble” position?
The first nucleotide (at the 5’ end) of the tRNA anticodon is the wobble position.
What complex directs the elongation of a polypeptide chain by reading mRNA?
The ribosome.
