Fig. 8.12 Transcription and processing of mRNA in eukaryotes,
Protein folding begins as translation proceeds, with enzymes and chaperone proteins assisting the amino acid chain in assuming its final functional form.
Fig. 8.16 Translation process of protein synthesis in prokaryotes.
that are present in mRNA and contain the information of proteins are known as exons. Thus, HnRNA produced after transcription is quite longer than the mRNA. Most of the extra nucleotide sequences, including introns, are cleaved by snurp. Moreover, after removal of the extra nucleotides from the 3′ end of the HnRNA, poly A tail is added that is required for the stability of the mRNA. Similarly, after removal of extra nucleotides from the 5′ end, a cap of 7-methyl guanosine (7mG) is added that is required for the translation process. The production and processing of HnRNA occurs in the nucleus from where it escapes into the cytoplasm through nuclear pores for the translation process (Fig 8.11 and 8.12).
In prokaryotes, the transcription and translation processes occur simultaneously as there is no nuclear membrane to separate the genetic DNA and the cytoplasm.
Protein Synthesis -Translation and Regulation
Ribosomal RNA and proteins form ribosomes, which physically support the other participants in protein synthesis and help catalyze formation of bonds betweens amino acids.
Protein synthesis - Biology-Online Dictionary
5. After initiation of the translation process, elongation process for the formation of dipeptide and ultimately the polypeptide chain is started by the attachment of AA2-tRNAAA2 (amino acyl tRNA or second amino acid attached with its specific tRNA) at its respective codon at the empty A-site with the help of the elongation factors EFTu (temperature unstable elongation factor) and EFTs (temperature stable elongation factor). This process also requires GTP. (In eukaryotes the elongation factors eEF1 and eEF2 are involved in the elongation process).
Protein Synthesis – Easy Peasy All-in-One High School
RNA takes that information into the cytoplasm, where the cell uses it to construct specific proteins, RNA synthesis is transcription; protein synthesis is translation.
Translation—Protein Synthesis*# - Biology LibreTexts
9. As the ribosome moves by two codons, next round of protein synthesis is initiated by the attachment of a new ribosome. Thus, at a time, a single mRNA is found to be attached with many ribosomes with their polypeptides of different length, (shortest polypeptide at the 5′ end of the mRNA and longest at the 3′ end), called polysomes.
Fig. 8.15 Peptide bond formation in growing polypeptide.
10. Ultimately, the A-site of ribosome is occupied by the termination codon (UAA,UAG or UGA) at the 3′ end of mRNA, which is not recognized by any tRNA. Thus, the termination of the protein synthesis is helped by the release factors RFl, RF2 and RF3 (in eukaryotes eRF1), which release the newly synthesized polypeptide chain from the P-site (Fig. 8.16).