Central Dogma
Basic principle
- DNA in genomes doesn't direct protein synthesis itself, but uses RNA as intermediate.
- When cell needs a particular protein, the nucleotide sequence of the portion of the very long DNA molecule in chromosome is first copied into RNA (via transcription).
- RNA copies of segment of DNA used as template to direct synthesis of the protein (via translation).
- SO... Flow of genetic info in cell from DNA → RNA → Protein!
- All cells from bacteria to humans express their genetic info this way, hence called --> CENTRAL DOGMA of molecular biology.
- Read background info on page 299 (Mol bio of the cell, 6th ed)
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Sequential Information
The genetic code is a true code meaning:
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From DNA To RNA
- Transcription and translation → means by which cells read out, or express genetic instructions in their genes.
- Many identical RNA copies can be made from same gene.
- Each RNA can direct synthesis of many identical protein molecules
- Which means that cells can direct synthesise of large amount of protein from a gene when needed!
- Genes can be transcribed and translated at different efficiencies, so the cell is able to control the amount of proteins made (so might make vast quantities of some proteins and tiny amount of others).
- Cell can change (or regulate) the expression of each of its gene according to its needs (by controlling production of its RNA!)