CENTRAL DOGMA :: PART 7

POST TRANCRIPTIONAL MODIFICATIONS

Genes in eukaryotes contain introns (non–coding regions) which are not necessary for protein synthesis. The removal of these introns and joining of all exons (coding region of a gene) is called post transcriptional modification. It takes place only in Eukaryotes, as prokaryotes don’t have introns in their genes.  

Splicing is important because

(1)    It’s a process of maturation.

(2)    The new mRNA is likely to get attacked by enzymes which degrade RNA.

(3)     The non-coding part is removed, only the coding part in retained.

What Happens in Splicing?

(

1)   Capping and tailing i.e., 7-methylguanosine is added to one end and a long chain of Adenosine is added to another end.

(2)    The unwanted (which are not useful in protein production) parts in mRNA are removed and the rest are joined to form a fully mature mRNA. It is than send to cytoplasm for translation.

(3)    The mRNA from which gives rise to a mature mRNA is called a pre-mRNA.  

CENTRAL DOGMA :: PART 6

TRANSCRIPTION

-          The process of formation of mRNA from DNA is called transcription.

-          mRNA can be made from both RNA and DNA with the help of different enzymes.

-          DNA dependent RNA polymerase makes a RNA copy of the required part of the DNA.

-          This takes place in the nucleus and the mRNA comes into the cytoplasm to synthesize protein.

                    

-          Before synthesis of proteins and after formation of mRNA, the produced mRNA undergoes a chain of changes called post transcriptional modifications.

CENTRAL DOGMA :: PART 5

ROLE OF RIBOSOMES

-          mRNA is made from DNA and this is the information that is further used for the synthesis of proteins.  

-          mRNA sits between the larger and the smaller subunit of the ribosome.

-          Ribosomes help in the synthesis of proteins both in eukaryotes and prokaryotes.

                          

-          But the ribosomes involved are different. 70s in prokaryotes and 80s in eukaryotes.

CENTRAL DOGMA :: PART 4

INTERMEDIATE LANGUAGE

-          DNA is made of nucleotides and proteins are made of amino acids and do not have any molecule in common, but still proteins are produced from DNA.

-          When DNA is converted into mRNA a set of 3 nucleotides are called a codon and these function as an intermediate language.

-          There are 64 possible codons with different possible and each codon encode for a different amino acid.

                   

-          This codons are recognised by the tRNA and sets a specific amino acid.

CENTRAL DOGMA :: PART 3

ENZYMES INVOLVED

-          RNA polymerase: - this enzyme is more like DNA polymerase that makes a
                                   RNA copy of genetic material (DNA or RNA).

                                           

-          Aminoacyl tRNA synthetase : - this enzyme helps in protein syntheses by
                                                    attaching amino acid to tRNA which in turn
                                                    make proteins.