This question is long and it is late here, but I can help you understand it. DNA consists of 4 nucleotide bases: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). When DNA is transferred to RNA, you use the complimentary nucleotide base to each as follows:
Adenine changes to Uracil (replaces Guanine in RNA)
Thymine changes to Adenine
Cytosine to Guanine and vice versa
So, the DNA code ‘TAC’ will have the mRNA complimentary strand of ‘AUG’. When changing mRNA to tRNA, you do as follows:
Change A to U
U to A
C to G
G to C
It’s that simple. Then, to change to amino acids, you need to use the codon chart attached (a codon is 3 nucleotide base pairs)
For example, mRNA codon AUG codes for the amino acid Methionine. Hope this helps.
