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a level biology help

i'm stuck why the answer was 70
i got where the 42 for A and T came from but why is it that you add all the bases together and then divide by three first then 2 to get 70?
(edited 1 year ago)
Reply 1
Hey I don’t do a level bio but let’s figure it out!

AT CG
If there’s 168 guanine bases then shouldn’t there ha an equal number of cytosine bases?

3 bases (a codon) codes for 1 amino acid. Thus, to get the number of amino acids, you have to divide the total number of bases by 3.

I’m thinking you divide by 2 after because there’s 2 strands of DNA right? Opposite bases on opposite strands are complementary so wouldn’t the gene code for 2 types of the same amino acid, in which case you’d divide by 2 to work out the different types of amino acids.

Sorry I couldn’t be of much help! Let me know if you get the answer- I’m curious!

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