`->` Specific activated amino acid is recognised by its specific t-ENA.

`->` Now amino acid attaches to the 'Amino acid attachment site' of its specific t-RNA and AMP and enzyme are separated from it.

`->` Amino acyl t-RNA complex is also called 'Charged t-RNA' .

`->` Now Amino acyl t-RNA moves to the ribosome for protein synthesis

{A) Initiation of polypeptide chain :-

`->` In this step 30 's' and 50 's' sub units of ribosome, GTP, Mg+2 , charged t-RNA, m-RNA and some initiation factors are required .

`->` In prokaryotes there are three initiation factors present - `lfl, IF2, IF3`.

`->` In Eukaryotes more than 3 initiation factors are present. Ten initiation factors have been identified in red blood cells -

`elfl, elf2, elf3, elf4A, elf4B, elf4C, elf4D, elf4F, elf5, elf6`


`->` Initiation factors are specific protein.

`->` GTP and initiation factors promote the initiation process.

`->` Both sub units of ribosome are separated with the help of `IF3` factor .

`->` In prokaryotes with the help of "S D sequence" (Shine-Delgarno sequence) m-RNA recognises the smaller sub unit of ribosome. A sequence of 8 N2 base is present before the `4-12 N_2` base of initiation codon on mRNA, called "SD sequence". In Smaller subunit of ribosome, a complementary sequence of "SD sequence" is present on `16` 'S' rRNA, which is called "Anti Shine-Delgamo sequence"
(ASD sequence)

`->` With the help of 'SD' and 'ASD sequence' mRNA recognises the smaller sub unit of ribosome .

`->` This "30 'S' m-RNA- complex" reacts with 'Formyl methionyl t-RNA- complex' and "30'S' m-RNA- formyl methionyl t-RNA- complex" is formed. This t-RNA attaches with codon part of m-RNA. A GTP molecule is required.

`->` Now larger sub unit of ribosome (50 'S' sub unil) joins this complex. The initiation factors released and complete 70 'S' ribosome is formed.
`->` In larger sub unit of ribosome there are three sites for t-ENA -·
'P' site = Peptidyl site.
'A' site = Amino acyl site.
'E' site = Exit site

`->` Starting codon of m-RNA is near to 'P' site of ribosome, sot-RNA with formyl methionine amino acid first attaches to 'P' site of ribosome and next codon of m-RNA is near to 'A' site of ribosome. So next newt-RNA with new amino acid always attach at 'A' site of ribosome but in initiation step 'A' site is empty.

`->` New tRNA with new amino acid is attaches at 'A' site of ribosome.

`->` The link between amino acid of 'P' site of t-ENA is broken and t-RNA of P-site is discharged so - `COOH` of P-site A.A. becomes free.

`->` Now peptide bond takes place between `- COOH` group of P site amino acid and `- NH_2` group of A-site amino acid.

`->` Peptidyl transferase enzyme induces the formation of peptide bond. In peptide bond formation , `23`'S' r-RNA is also helpful. This r-HNA ads as an enzyme so it is also called "Ribozyme".

`->`After formation of peptide bond t-RNA of P site released from ribosome via E-site nd dipeptide attaches with A site.

`->` Now t-RNA of A site is transferred to P site and :. A site becomes empty.

`->` Now ribosome slides over m-ENA strand in 5' -> 3' direction. Due to sliding of ribosome on M-RNA, new codon of m-ENA continuously available at A site of ribosome and according to new codon of m-RNA new amino acid attaches in polypeptide chain.

`->` Translocase enzyme is helpful in movement of ribosome (translocation). GTP provides energy for sliding of ribosome.


`->` In elongation process some protein factors are also helpful. which are known as 'Elongation warTnT'"

`->` In prokaryotes three 'Elongation factors' are present `- EF-Tu, Ef-Ts, EF-G`.

`->` In Eukaryotes two elongation factors are present -- `eEF1, eEF2`.

`->` Due to sliding of ribsome over m-RNA when any Nonsense codon `(UAA, UAG, UGA)` available at A site of ribosome, then polypeptide chain terminates.

`->` The linkage between the last I-RNA and the polypeptide chain is broken by three release factor called `RFl, RF2, RF3` with the help of GTP .

`->` In eukaryotes only one Release Factor is known - `eRFl`.

`->` An mRNA also have some additional sequences that are not translated and are referred as untranslated regions (UTR). The UTRs are present at both S'end (before start codon) and at 3'end (after stop codon).

`->` The UTR(untranslated regions) present on mRNA are required. for efficient translation process (by recognising the smaller subunit of ribosome by mRNA)

1. The chargaff's rule is not valid (true) for RNA. It is valid only for double helical DNA. i.e. for RNA it is `A ne U` and `G ne C`.

2. The duplication of DNA was first of all proved in E. coli bacterium.

3. E. coli Bacterium is mostly used for the study of DNA duplication.

4. Hargovind singh Khurana first of all recognised the triplet codon for Cysteine and Valine amino adds.

5. Cytoplasmic DNA is `1 - 5%` of total cell DNA.

6. Three scientists named Avery, Me- Leod and Me Carty (by their transformation experiments on bacteris) Proved that DNA is a genetic material.

7. Hershey and Chase first of all proved that DNA is genetic material in bacteriophages

8. frankel and Conret proved, RNA as a genetic material in viruses (g-RNA).

9. `tt ( (text(AUC)) , (text(ACU)) , (text(AUU)) ) }` These anticodons do not exist.

10. The structure formed by the combination of m - RNA and Ribosomes is known as polyribosomes/Polysomes/ Ergosomes

11. The formation of t - RNA takes place from the heterochromatin part of DNA.

12. The formation of m - RNA takes place from the Euchromatin part of DNA.

13. m - RNA is least stable. It is continuously formed and finished.

14. In cytoplasm, t - RNA is present in the form of soluble colloid.

15. Nucleases :- Nucleases are the breaking enzymes of nucleic acids. These are of two types :{
(1) Endo-Nucleases :- These break down the nucleic acids from the inside.
(2) Exo-nucleases :- These break down the nucleic acids from the ends(terminal ends).

These separate each nucleotide.

16. Some Inhibitors of Bacterial Protein Synthesis :

`->` Mic RNA : It is synthesized some1ime on the sense strand of DNA which is complementary of Antisense strand which is used for mRNA synthesis. Such ENA is used for regulation of gene expression at the level of translation.

`->` Higher Nucleotide : Nucleotides which contain more than one phosphate i.e. ATP, ADP.

`->` Iodine number : It is the amount of iodine in gram absorbed by 100 gram fat. 11 is used to determine the degree of unsaturation of fat.

`->` Second genetic code : Interaction between specific t-ENA and amino acyl synthetase enzyme is known as second genetic code.

GLUT-4 (Glucose transport 4) Proteins : It is a transport protein thai allows glucose to enter a cell.

`->` DNA-quenching : Rapid cooling of denatured DNA, fix it in permanently denatured form, lt is called DNA. quenching .

`->` Secondary metabolites: These are the product of metabolic reactions but they do not directly involve in the growth, reproduction and development of these organism. Many secondary metabolites are used in human-welfare. eg. drugs, rubber, spices etc.