Central dogma

Central dogma ( DNA replication, m-RNA synthesis and protein synthesis) of genetic material in genetics and molecular biology

1. CENTRAL DOGMA A PRESENTATION ON PRESENTED BY SAIKAT JANA SEM: IV ROLL: 91 DEPT. OF BOTANY NARAJOLE RAJ COLLEGE

2. WHAT IS CENTRAL DOGMA A theory in genetics and molecular biology subject to several exceptions that genetic information is coded in self replicating DNA and undergoes unidirectional transfer to m-RNA in transcription which act as templates for protein synthesis in translation.

3. There are three main steps in the process ‘central dogma’― 1. Replication 2. Transcription 3. Translation This theory was first proposed in 1958 by Francis Crick , discoverer of the structure o f DNA.

4. Fig. Central dogma

5. REPLICATION The process by which a double stranded DNA molecule is copied to produce two identical DNA molecules. DNA replication takes place by three steps― 1. Initiation 2. Elongation 3. Termination

6. 1. INITIATION The double helix DNA bind helicase enzyme and unwind by breaking the H-bonds between complementary base pairs. Fig. Initiation

7. 2. ELONGATION A new DNA strand grows one base at a time. The existing strand is a template for the new strand. The enzyme DNA polymerase controls the process. 3. TERMINATION Two new double stranded DNA have replaced the original helix. Finally, nuclease enzyme proofread the new double helix structure and remove mispaired bases. DNA polymerase fills the gaps created by the excised bases.

8. TRANSCRIPTION Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA). Transcription is carried out by an enzyme called RNA polymerase and a number of accessory proteins called transcription factors. Transcription occurs in the three steps— 1. I nitiation 2. Elongation 3. T ermination

9. A enzyme RNA-polymarase bind to promoter region. Unwind the double helix and form transcription bubble. RNA-polymarase read the nucleotide sequence and copy to m-RNA. 1. INITIATION

10. RNA-polymarase moves along the template strand and synthesising an m-RNA molecule. 2. ELONGATION

11. There are two way of termination- Rho- dependent: A protein factor called Rho-factor is responsible for disrupting RNA-polymarase from template strand. Rho- independent: A loop forms at the end of the RNA molecule for detach itself. 3. TERMINATION

12. Fig: whole process of transcription

13. In molecular biology and genetics, translation is a process in which protein synthesized from m-RNA by ribosome in the cytoplasm of a cell. It also has three parts― 1. Initiation 2. Elongation 3.Termination TRANSLATION

14. The ribosome assembles around the target mRNA. The first tRNA is attached at the start codon.  1. INITIATION

15. The t-RNA forms an amino acid by read the codon sequence. The ribosome then moves to the next m-RNA codon to continue the process and creating an amino acid chain. 2. ELONGATION

16. When a peptidyl t-RNA binds with a stop codon, then the ribosome folds the polypeptide into its final structure. 3. TERMINATION

17. Fig: whole process of translation

18. Thank you