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 of 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.

9. 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. Initiation
2. Elongation
3. Termination

10. • 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

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

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

13. Fig: whole process of transcription

14. 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

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

16. 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

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

18. Fig: whole process of translation

19. Thank you