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| Central Dogma of Molecular Biology |
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| The expression of the genetic material occurs generally through the production of proteins. |
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| This involves 2 consecutive steps which are: |
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 Transcription |
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 Translation |
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| Transcription |
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| In transcription the genetic information, stored in DNA is transferred to an RNA intermediate, for translation. |
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| Translation |
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| The RNA intermediate uses this information to direct the synthesis of proteins during translation. This unidirectional flow of information was described by F. H. C. Crick in 1958 as the Central Dogma of Molecular Biology. |
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| In 1970, H. M. Jennin and D. Baltimore brought to light an important modification of this information flow. |
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| Many tumour viruses contain RNA as genetic material and replicate by first synthesising a complementary DNA. This process is called reverse transcription. It is carried out by an RNA dependent DNA polymerase called reverse transcriptase. |
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| These viruses are known as retroviruses and include HIV (human immunodeficiency virus) that causes AIDS. So the central dogma is now represented as |
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