Protein biosynthesis is the process by which biological cells generate new proteins. Here are the reasons for some protein synthesis related molecular events.
1.Transcription is especially important in terms of gene expression.
– Because transcription is the point where most of the regulation of gene expression occurs.
2. Dissociation of sub-unit of ribosome is essential for initiation.
– Because the initial binding (F-Met-tRNA) in prokaryotes and Met-tRNA in eukaryotes occurs on small sub-unit of ribosomes.
3. In prokaryotes, protein synthesis starts even before mRNA synthesis is completed.
– Because prokaryotes lack a nuclear membrane. Thus, there is no separation between genome and ribosome.
4. Sequences of mRNA vary.
– Because at this end of tRNA, amino acid is attached.
5. The cell needs some way of transferring genetic information from the nucleus to the cytoplasm.
– Because the synthesis of proteins take place in the cytoplasm (outside the nucleus).
6. The core enzyme RNA polymerase by itself is not able to transcribe RNA.
– Because it transcribes on both strands.
7. The P site of ribosome is so named.
– Because it binds only to initiator peptidyl-tRNA molecule (except in the inititator tRNA), a tRNA with growing peptide attached.
8. Transcription is asymmetrical.
– Because, out of two strands of DNA, only one strand is used as a template for transcription.
9. Noncoding regions are functionally important.
– Because their sequence has tended to be conserved through evolution.
10. the TATA box is important for transcription.
– Because it has been reported that probably its function mainly is to precisely position the start of transcription.
11. N-formyl methionine is unable to form a a peptide bond.
– Because, its end bearing the free amino acid is blocked by the formylation reaction.
12. Several eukaryotic mRNA can be purified.
– Because they are stable.
13. Each ribosome functionally accommodates two codons at a time.
– Because each ribosome has two binding sites called A (aminoacyl) and P (Peptidyl) sites.
14. Transfer RNA is so called?
-Because it carries activated amino acids from the cytoplasm to the site of protein synthesis (ribosomes).
15. Inhibition of translation results in less fertilization.
-Because when protein translation is inhibited, capacitation becomes impaired and fertilization is much less likely.
16. Hydrogen bonds are important for protein synthesis.
– Because hydrogen bonds are needed for the formation of hydride bridges resulting in twisting of protein molecules in their unusual shapes. Many proteins are used in cells as lock and key and thus without a proper shapes, the keys will not fit into the
lock and key and thus without a proper shapes, the keys will not fit into the locks. Ultimately, the proteins will be useless for continuing the process.
17. Prokaryotic mRNA molecules are free to attach to ribosomes are they are being synthesized.
– Because prokaryotes lack nuclear membrane.
18. Appearance of UAA, UAG, or UGA codon on mRNA prevents elongation of the polypeptide chain.
– Because no tRNA molecules bear anticodons to pair with nonsense codons (UAA, UAG, and UGA), so appearance of such codons on mRNA prevent elongation of polypeptide chain.
19. Formation of peptide bond does not require energy.
– Because amino acid brought by tRNA is already activated.