Protein Synthesis - Protein Synthesis Worksheet

         Protein synthesis worksheet 

The process of formation of protein from.its constituent materials is called as protein synthesis. It includes 2 steps.

• Transcription
• Translation 

They are explained below.

Transcription 

1. This process includes the formation of m-RNA from DNA.
2. Transcription takes place in only one strand of DNA.
3. It normally occurs in 5'-3' direction.
4. During transcription, the DNA site at which RNA polymerase binds is called promoter site.

Transcrption in various organisms takes place in various process.
Transcription in Prokaryotes 

• Transcription of all the three types of RNA occurs in the presence of single enzyme called as RNA polymerase.
• 
  
• The Inhibitor of transcription in prokaryotes is Rifampcin. 
  

Transcription in Eukaryotes .
Three different enzymes are found in transcription in eukaryotes .

• RNA polymerase-1 : It transcribes r-RNA in nucleolus except 5-s rRNA.
• RNA polymerase-2 : It transcribes m-RNA in nucleoplasm.
• RNA polymerase-3 : It transcribes t-RNA and 5-s rRNA.

Note:- aplha-Amanitin is the inhibitor of transcription in eukaryotes.

• Transcription starts with the separation of DNA strand.
• m-RNA formed after transcription is called primary transcript.

For primary transcript
Coding part is EXON.
Non-Coding part is INTRONS.

• Removal of introns from exon is called splicing.
• After splicing m-RNA undergoes methylation (Addition of 7 methyl guanosine  at 5' end) and polyadenylation (Addition of polyadenine at 3' end).
• Methylation is for the protection of initiation codon.
• Polyadenylation is for the protection of 3' end.
• m-RNA formed after methylation and adenylationis called matured m-RNA.

Translation 

1. It is the formation of protein from m-RNA.
2. It occurs in 5'-3' direction.
3. Amino acid is activated (it requires ATP and enzymes).
4. Activated amino acid is charged on t-RNA.
5. Small sub- unit pf ribosomes is attached to the messenger RNA.
6. Then larger sub-unit of ribosome is fused to this complex .
7. Large sub-units of ribosome has  basically 2 sieds.
8.     P site- peptidyl site :- Here the peptide bind is formed.
9.     A site- amino acyl site :- The new amino acid comes to this site.
10. The first amino acid always comes to P site.
11. Next amino acid comes to A site.
12. COOH group of first amino acid and NH2 group of next form peptide bond.
13. This dipeptide moves from A site to P site in presence of enzyme translocase.
14. This process is continued till it reaches termination codon.
15. At last releasing factor release polypeptide and protein synthesis is complete.

Reverse transcription 

• It occurs in retrovirus 
• It was discovered by Temin nad Baltimore in Rous Sarcoma Virus.
• Reverse Transcription is also called as Teminism
• Reverse transcription is RNA> DNA >RNA >protein.
• Flow of information is bidirectional.                                                        If you liked our Article on Protein Synthesis, do share the content.