How to calculate the number of amino acids encoded by a DNA strand?

[Ariel M]

How can I calculate the number of amino acids from a coding strand of DNA?

Should I go for the complementary strand?

 

[A. Hammouda]

You should not go for the complementary strand.

The DNA coding strand has the same sequence like mRNA except that U is replaced by T.

Please examine the attached file showing a table of genetic code (codons).

Look at your coding DNA strand, starting from 5′-end find the first ATG sequence that represents methionine codon and the first amino acid in sequence. Count the triplets (codons) which follow this starting codon until you reach a stop (termination), which is not counted.

The attached table shows that termination codons are UAA, UAG, and UGA. In the DNA coding strand, these are TAA, TAG, and TGA.

Good luck.

 

 

 

 

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