15. If the DNA reads TAC, what does the mRNA read? AAG ACG ATG AUG

## Step 1<br />In the process of transcription, the DNA sequence is copied into mRNA. The DNA sequence is read in the 5' to 3' direction, and the mRNA is synthesized in the 3' to 5' direction.<br /><br />## Step 2<br />The DNA sequence is composed of four types of nucleotides: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). In the DNA sequence, Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).<br /><br />## Step 3<br />However, in the mRNA, Thymine (T) is replaced by Uracil (U). Therefore, when the DNA sequence is TAC, the mRNA sequence will be AUG.