BRAINCAKEThe Genetic Code
The genetic code is the set of rules by which the base sequence of DNA (and mRNA) is converted into the amino acid sequence of a polypeptide.
Its key features are:
• Triplet code: a sequence of three bases codes for one amino acid. On mRNA each triplet is called a codon. With four bases there are 43 = 64 possible codons, more than enough for the 20 amino acids. A doublet code (42 = 16) would not be enough.
• Degenerate: most amino acids are coded for by more than one codon. For example, glycine is coded by GGU, GGC, GGA and GGG.
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More in DNA, Genes and Protein Synthesis
- Phosphodiester Bonds
- Complementary Base Pairing
- Evidence for Semi-Conservative DNA Replication
- DNA Replication
- Types of RNA
- mRNA
- tRNA
- rRNA
All 20 lessons in DNA, Genes and Protein Synthesis · All Edexcel AS-level Biology topics