Biology
There are three stages of translation. First, in initiation, a small subunit of ribosome binds to the mRNA transcript. Then, each aminoacyl-tRNA synthetase catalyses teh coupling of aminoacyl-tRNA to its specific amino acid. The first tRNA molecule, carrying methionine, occupies the peptidyl-tRNA site of the ribosome, alongside initiation factors. Initiation factors then dissociate from the small ribosomal subunit and make way for the large ribosomal subunit. For prokaryotes, small ribosomal subunit binds to its recognition sequence. The large ribosomal subunit joins the initiator complex. In the second phase, elongation, the second amino acid tRNA complex occupies the aminoacyl-tRNA site of the ribosome. Peptidyl transferase catalyses the formation of a peptide bond between teh two amino acids and the dipeptide is on the tRNA in the A site. Ribosome then translocates by a codon in the 5' to 3' direction. tRNA present in the A site is now translocated to the P-site and the uncharge tRNA in teh P site enteres and E site and is released. In the final stage, termination, the ribosome encounteres the stop codon (UAA, UAG, or UGA). Release factors bind directly to the stop codon mRNA and ribosome dissociates from one another, thus releasing the newly synthesized polypeptide.
- Bypassing Involves Ribosome Movement
Certain sequences trigger a bypass event, when a ribosome stops translation, slides along mRNA with peptidyl-tRNA remaining in the P site, and then resumes translation (see Figure 7.30). This is a rather rare phenomenon, with only ~3 authenticated examples...
- The Polypeptide Chain Is Transferred To Aminoacyl-trna
KEY TERMS:Peptidyl transferase is the activity of the ribosomal 50S subunit that synthesizes a peptide bond when an amino acid is added to a growing polypeptide chain. The actual catalytic activity is a property of the rRNA. Puromycin is an antibiotic...
- Use Of Fmet-trnaf Is Controlled By If-2 And The Ribosome
KEY TERMS:The context of a codon in mRNA refers to the fact that neighboring sequences may change the efficiency with which a codon is recognized by its aminoacyl-tRNA or is used to terminate protein synthesis. KEY CONCEPTS: IF-2 binds the initiator...
- Initiation In Bacteria Needs 30s Subunits And Accessory Factors
KEY TERMS:A ribosome-binding site is a sequence on bacterial mRNA that includes an initiation codon that is bound by a 30S subunit in the initiation phase of protein synthesis. An initiation complex in bacterial protein synthesis contains a small ribosome...
- Protein Synthesis Occurs By Initiation, Elongation, And Termination
KEY TERMS:The A site of the ribosome is the site that an aminoacyl-tRNA enters to base pair with the codon. The P site of the ribosome is the site that is occupied by peptidyl-tRNA, the tRNA carrying the nascent polypeptide chain, still paired with the...
Biology
Q: Describe how globular proteins are synthesized after mRNA have been formed
There are three stages of translation. First, in initiation, a small subunit of ribosome binds to the mRNA transcript. Then, each aminoacyl-tRNA synthetase catalyses teh coupling of aminoacyl-tRNA to its specific amino acid. The first tRNA molecule, carrying methionine, occupies the peptidyl-tRNA site of the ribosome, alongside initiation factors. Initiation factors then dissociate from the small ribosomal subunit and make way for the large ribosomal subunit. For prokaryotes, small ribosomal subunit binds to its recognition sequence. The large ribosomal subunit joins the initiator complex. In the second phase, elongation, the second amino acid tRNA complex occupies the aminoacyl-tRNA site of the ribosome. Peptidyl transferase catalyses the formation of a peptide bond between teh two amino acids and the dipeptide is on the tRNA in the A site. Ribosome then translocates by a codon in the 5' to 3' direction. tRNA present in the A site is now translocated to the P-site and the uncharge tRNA in teh P site enteres and E site and is released. In the final stage, termination, the ribosome encounteres the stop codon (UAA, UAG, or UGA). Release factors bind directly to the stop codon mRNA and ribosome dissociates from one another, thus releasing the newly synthesized polypeptide.
- Bypassing Involves Ribosome Movement
Certain sequences trigger a bypass event, when a ribosome stops translation, slides along mRNA with peptidyl-tRNA remaining in the P site, and then resumes translation (see Figure 7.30). This is a rather rare phenomenon, with only ~3 authenticated examples...
- The Polypeptide Chain Is Transferred To Aminoacyl-trna
KEY TERMS:Peptidyl transferase is the activity of the ribosomal 50S subunit that synthesizes a peptide bond when an amino acid is added to a growing polypeptide chain. The actual catalytic activity is a property of the rRNA. Puromycin is an antibiotic...
- Use Of Fmet-trnaf Is Controlled By If-2 And The Ribosome
KEY TERMS:The context of a codon in mRNA refers to the fact that neighboring sequences may change the efficiency with which a codon is recognized by its aminoacyl-tRNA or is used to terminate protein synthesis. KEY CONCEPTS: IF-2 binds the initiator...
- Initiation In Bacteria Needs 30s Subunits And Accessory Factors
KEY TERMS:A ribosome-binding site is a sequence on bacterial mRNA that includes an initiation codon that is bound by a 30S subunit in the initiation phase of protein synthesis. An initiation complex in bacterial protein synthesis contains a small ribosome...
- Protein Synthesis Occurs By Initiation, Elongation, And Termination
KEY TERMS:The A site of the ribosome is the site that an aminoacyl-tRNA enters to base pair with the codon. The P site of the ribosome is the site that is occupied by peptidyl-tRNA, the tRNA carrying the nascent polypeptide chain, still paired with the...