Editing Common descent (section)

===Common genetic code===
{{further|Genetic code}}
{| class="wikitable floatright" style="border: none; text-align: center;"
| '''[[Amino acid]]s'''
| style="background-color:#ffe75f; width: 50px;" | nonpolar
| style="background-color:#b3dec0; width: 50px;" | polar
| style="background-color:#bbbfe0; width: 50px;" | basic
| style="background-color:#f8b7d3; width: 50px;" | acidic
| style="border: none; width: 75px;" |
| style="background-color:#B0B0B0;" | Stop codon
|}

{| class="wikitable floatright"
|+ Standard genetic code
!rowspan=2| 1st<br />base
!colspan=8| 2nd base
|-
!colspan=2| {{{T|T}}}
!colspan=2| C
!colspan=2| A
!colspan=2| G
|-

!rowspan=4| {{{T|T}}}
| {{{T|T}}}{{{T|T}}}{{{T|T}}}
|rowspan=2 style="background-color:#ffe75f" | [[Phenylalanine|Phenyl-<br>alanine]]
| {{{T|T}}}C{{{T|T}}}
|rowspan=4 style="background-color:#b3dec0" | [[Serine]]
| {{{T|T}}}A{{{T|T}}}
|rowspan=2 style="background-color:#b3dec0" | [[Tyrosine]]
| {{{T|T}}}G{{{T|T}}}
|rowspan=2 style="background-color:#b3dec0" | [[Cysteine]]

|-
| {{{T|T}}}{{{T|T}}}C
| {{{T|T}}}CC
| {{{T|T}}}AC
| {{{T|T}}}GC

|-
| {{{T|T}}}{{{T|T}}}A
|rowspan=6 style="background-color:#ffe75f" | [[Leucine]]
| {{{T|T}}}CA
| {{{T|T}}}AA
| style="background-color:#B0B0B0;" | [[Stop codon|Stop]] <!--(''Ochre'')-->
| {{{T|T}}}GA
| style="background-color:#B0B0B0;" | [[Stop codon|Stop]] <!--(''Opal'')-->

|-
| {{{T|T}}}{{{T|T}}}G
| {{{T|T}}}CG
| {{{T|T}}}AG
| style="background-color:#B0B0B0;" | [[Stop codon|Stop]] <!--(''Amber'')-->
| {{{T|T}}}GG
| style="background-color:#ffe75f;" | [[Tryptophan]]&nbsp;<!-- to make the columns roughly the same width -->

|-

! rowspan="4" | C
| C{{{T|T}}}{{{T|T}}}
| CC{{{T|T}}}
|rowspan=4 style="background-color:#ffe75f" | [[Proline]]
| CA{{{T|T}}}
|rowspan=2 style="background-color:#bbbfe0" | [[Histidine]]
|CG{{{T|T}}}
|rowspan=4 style="background-color:#bbbfe0" | [[Arginine]]

|-
|C{{{T|T}}}C
|CCC
|CAC
|CGC

|-
|C{{{T|T}}}A
|CCA
|CAA
|rowspan=2 style="background-color:#b3dec0" | [[Glutamine]]
|CGA

|-
|C{{{T|T}}}G
|CCG
|CAG
|CGG

|-

! rowspan="4" | A
|A{{{T|T}}}{{{T|T}}}
|rowspan=3 style="background-color:#ffe75f" | [[Isoleucine]]
|AC{{{T|T}}}
|rowspan=4 style="background-color:#b3dec0" | [[Threonine]]&nbsp;<!-- to make the columns roughly the same width -->
|AA{{{T|T}}}
|rowspan=2 style="background-color:#b3dec0" | [[Asparagine]]
|AG{{{T|T}}}
|rowspan=2 style="background-color:#b3dec0" | [[Serine]]

|-
|A{{{T|T}}}C
|ACC
|AAC
|AGC

|-
|A{{{T|T}}}A
|ACA
|AAA
|rowspan=2 style="background-color:#bbbfe0" | [[Lysine]]
|AGA
|rowspan=2 style="background-color:#bbbfe0" | [[Arginine]]

|-
|A{{{T|T}}}G
| style="background-color:#ffe75f;" | [[Methionine]]
|ACG
|AAG
|AGG

|-

! rowspan="4" | G
|G{{{T|T}}}{{{T|T}}}
|rowspan=4 style="background-color:#ffe75f" | [[Valine]]
|GC{{{T|T}}}
|rowspan=4 style="background-color:#ffe75f" | [[Alanine]]
|GA{{{T|T}}}
|rowspan=2 style="background-color:#f8b7d3" | [[Aspartic acid|Aspartic<br>acid]]
|GG{{{T|T}}}
|rowspan=4 style="background-color:#ffe75f" | [[Glycine]]

|-
|G{{{T|T}}}C
|GCC
|GAC
|GGC

|-
|G{{{T|T}}}A
|GCA
|GAA
|rowspan=2 style="background-color:#f8b7d3" | [[Glutamic acid|Glutamic<br>acid]]
|GGA

|-
|G{{{T|T}}}G
|GCG
|GAG
|GGG

|-
|}

The [[genetic code]] (the "translation table" according to which DNA information is translated into [[amino acid]]s, and hence proteins) is nearly identical for all known lifeforms, from [[bacteria]] and [[archaea]] to [[animal]]s and [[plant]]s. The universality of this code is generally regarded by biologists as definitive evidence in favor of universal common descent.<ref name=Knight/>

The way that [[Genetic code|codon]]s (DNA triplets) are mapped to [[amino acid]]s seems to be strongly optimised. Richard Egel argues that in particular the [[hydrophobic]] (non-polar) side-chains are well organised, suggesting that these enabled the earliest organisms to create [[peptide]]s with water-repelling regions able to support the essential electron exchange ([[redox]]) reactions for energy transfer.<ref name=Egel>{{cite journal |last1=Egel |first1=Richard |title=Primal Eukaryogenesis: On the Communal Nature of Precellular States, Ancestral to Modern Life |journal=Life |date=March 2012 |volume=2 |issue=1 |pages=170–212 |doi=10.3390/life2010170 |pmc=4187143 |pmid=25382122|bibcode=2012Life....2..170E |doi-access=free }}</ref>