Central dogma of Molecular Biology with video of DNA replication, Transcription and Translation. It help to understand the basic of DNA structure and its function.

1. Molecular Biology: Central Dogma, DNA Replication, Transcription, Translation, mRNA processing
Dogma: (Greek word): A principle or set of principles laid down by an authority as incontrovertibly true.
Central Dogma of Molecular Biology
• The central dogma of molecular biology is an explanation of the flow of genetic information within a
biological system. It was first stated by Francis Crick in 1956 and re-stated in a Nature paper published in
1970.
• The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential
information. It states that such information cannot be transferred back from protein to either protein or
nucleic acid. — Francis Crick

4. DNA: Deoxyribonucleic acid
• DNA strands are termed polynucleotides since they are composed of simpler monomer units called
nucleotides
• Each nucleotide is composed of
I. one of four nitrogen-containing nucleobases—either cytosine (C),guanine (G), adenine (A), or thymine (T)
II. A sugar called deoxyribose
III. A phosphate group.

6. Nitrogenous base
Sugar molecule

8. E. coli I II III
Polymerization: 5′ → 3′ + + +
Exonuclease activity:
3′ → 5′ + + +
5′ → 3′ + − −
Synthesis from:
Intact DNA − − −
Primed single strands + − −
Primed single strands plus single-strand inding protein + − +
In vitro chain elongation rate (nucleotides per minute) 600 ? 30,000
Molecules present per cell 400 ? 10 – 20
Mutation lethal? + − +
Mammalian Cells* α β
†
γ δ ϵ
Polymerization: 5′ → 3′ + + + + +
Exonuclease proofreading activity:
‡
3 → 5′ − − + + +
Synthesis from:
RNA primer + − − + ?
DNA primer + + + + +
Associated DNA primase + − − − −
Sensitive to aphidicolin (inhibitor of ell DNA synthesis) + − − + +
Cell location:
Nuclei + + − + +