CENTRAL DOGMA :: PART 8

Translation

-          This process is involved in the synthesis of proteins.

Components involved in translation:

-          Mature mRNA, tRNA, Ribosome,

-          The mature mRNA attaches to the ribosomal sub units, which in turn come together to form a ribosome.

-          tRNA (transfer RNA) plays a vital role in this process, it picks up the complementary amino acids from to cytoplasm to the ribosome.

What happens during translation:

-          Mature mRNA enters the cytoplasm and ribosome attaches to it.

-          Three base pairs on the mRNA are known as codon.

-          Each tRNA contains anticodon for each amino acid.

-          Each tRNA can read the complementary codon and bring in the required amino acids which are joined my peptide bond in the ribosome.  

-          At the end of translation, a primary protein chain is synthesised. 

                                    

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.

                                            

CENTRAL DOGMA :: PART 2

TYPES OF RNA

-          mRNA: - (messenger RNA) This is an intermediate formed between DNA and    
                 protein. mRNA is made from DNA and proteins are made from mRNA.

                     

-          tRNA: - (transfer RNA) this RNA helps in the formation of a protein from amino
                acids. This gathers amino acid and joins them making a polypeptide.

                                             

-          rRNA: - (ribosomal RNA) it is the main constituent of ribosomes. This along with
                 the two other RNA make a polypeptide.

CENTRAL DOGMA :: PART 1

INTRODUCTION

-          In any organism proteins perform most of the activities and DNA control all the cellular functions.

-          The process by which a protein is made from DNA is called central dogma.

-          This is a multilevel process which includes complex mechanism like transcription, translation, post translational modifications and many more.

-          The end product of this process is a protein that is able to perform all cellular activity.

                                

DNA REPLICATION :: PART 7

                      

DNA REPLICATION:: PART 6

-         Primase: - This removes the RNA primer that initiates the
                       synthesis of the DNA strand.

                                          

-         

        DNA ligase: - This enzyme seals the nicks formed by making
                               phosphodiester bonds.

                                             

DNA REPLICATION:: PART 5

-         DNA polymerase: - This enzyme is responsible for the synthesis of
                                   new strand of DNA.

o   DNA polymerase can synthesise DNA strand only in 5’ to 3’ direction.

                          

o   This requires the presence of (dNTP) deoxyribonucleotide triphosphate.

DNA REPLICATION:: PART 4

ENZYMES REQUIRED IN DNA REPLICATION

-         Topoisomerase: - This unwinds the DNA and releases the super
                                    coiled structure of the double helix.

                                                

-         Helicase: - It breaks the hydrogen bonds between the two
                          strands of the DNA.

                                                   

DNA REPLICATION :: PART 3

-         First generation of E.coli.

o   The DNA from E.coli was extracted.

o   The isolated DNA had equal amounts of N15 and N14 in their DNA.

-         Second generation of E.coli. 

o   DNA from E.coli was extracted.

o   It had two DNA strands containing only N14 and two hybrid DNA strands containing N14 and N15.

DNA REPLICATION :: PART 2

SEMI-CONSERVATIVE MODE OF DNA REPLICATION

-         This is called semi conservative because the new strand of DNA contains one parental strand and one newly synthesized strand.

-         EXPERIMENT

o   N15 is a heavy isotope of nitrogen.

o   E.coli was grown in a nutrient medium that contained N15 instead of N14.

o   Hence N15 got incorporated into the purines and pyrimidines bases of the DNA.

                         

o   After this E.coli were removed from N15 medium and kept in N14 medium.

DNA REPLICATION:: PART 1

INTRODUCTION

-          This a cellular mechanism that involves the multiplication of a DNA fragments into two.

-          This process of multiplication of DNA into two is called DNA replication.

-          DNA replication involves a large number of enzymes.

-          DNA replication is called semi-conservative.

                                                          

-          This process of replication is important to pass on the genetic material to its future generations.