Genetic code: Difference between revisions

Revision as of 08:21, 30 January 2004

Revision as of 08:23, 30 January 2004

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This process is called [[protein biosynthesis]]. First, a sub-sequence of [[DNA]] called a [[gene]] is [[transcription|transcribed]] (rewritten) into [[RNA]]. An RNA is a sequence nucleotide bases. There are four types of base: [[adenine]], [[guanine]], [[cytosine]] and [[uracil]]. RNA is divided into groups of three bases, called codons. Each codon represents one amino acid. There are 64 possible codons. For example, the RNA sequence UUUAAACCC contains the codons UUU, AAA and CCC, each of which specifies one amino acid. So, this RNA sequence represents a protein sequence, three amino acids long. (In [[DNA]], the base [[thymine]] takes the place of uracil.)

The standard genetic code is shown in the following tables. [[#Table 1: Codon Table|Table 1]] shows what amino acid each of the 4³ = 64 codons specifies. [[#Table 2: Reverse Codon Table|Table 2]] shows what codons specify each of the 20 standard amino acids involved in translation. These are called forward and reverse codon tables, respectively. For example, the codon GAU represents the amino acid [[asparagine]] (Asp), and [[cysteine]] (Cys) is represented by UGU and by UGC.

<table 'id=Table 1' border=1 cellpadding=3 cellspacing=0 align=center>

<caption>

====Table 1 : Codon table. ====
This table shows the 64 codons and the amino acid each codon codes for.

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<table id='Table 2' border=1 cellpadding=3 cellspacing=0 align=center>

<caption>

====Table 2==== : Reverse codonCodon table.Table==== This table shows the 20 amino acids used in proteins, and the codons that code for each amino acid.

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