Before anything else please pay attention of the double quotes on the "equal" in the title - I know they are not equal, but you will understand in a bit.
If I look at the DNA codon table here or in wikipedia, and at the RNA codon table here or in wikipedia, their only difference is that the former has thymine (T) whereas the latter has uridine (U). But I am not understanding how all other nucleotides are the same. Bear in mind that transcription reads DNA from 3'->5' and translation reads mRNA from 5'->3'.
Look at this example, focusing on the 3'-TAC-5' of the antisense strand.
The 3'-TAC-5' codes for Tyrosine according to the DNA codon table. However, it transcribes and translates 3'-TAC-5' -> 5'-AUG-3' -> Methionine.
Now focus on the corresponding codon in the sense strand, 5'-ATG-3', which codes for Valine according to the DNA table (it is read from 3' to 5'). This codon transcribes and translates 3'-GTA-5' -> 5'-CAU-3' -> Histidine, not Valine and not Methionine.
So my questions are:
- Why do DNA codon tables show the correspondence between codons and amino acids in the sense strands (5'-ATG-3'), if the only way to go from ATG to Met as in the figure is to consider the antisense strand?
- I can see that the AUG codon translates to Methionine, and it is translated by reading the 3'-TAC-5' codon in antisense strand, whose corresponding codon in sense strand is 5'-ATG-3'. But this last one is read from 3'->5', so it reads 3'-GTA-5' -> 5'-CAU-3' -> His.
I am guessing I'm getting many things wrongly in this... Maybe on the way that I'm reading the tables: I always take into account that transcription is read 3'->5' and this is the order I take to read DNA tables.
Thank you and sorry if I was confusing.