__ Use the DNA code provided and fill in the complementary DNA strand. Which nitrogen base CAN'T you use during replication? __

## Step 1<br />In the process of DNA replication, the DNA molecule is copied to produce two identical DNA molecules. Each strand of the original DNA molecule serves as a template for the production of the complementary strand. The nitrogenous bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G). Adenine always pairs with thymine, and cytosine always pairs with guanine.<br /><br />## Step 2<br />The question asks which nitrogen base cannot be used during replication. The options provided are A, T, C, and G. Since the question is about the complementary strand, we need to consider which base would not pair with any of the original bases.<br /><br />## Step 3<br />In the context of DNA replication, the nitrogen base that cannot be used is uracil (U). Uracil is a nitrogenous base found in RNA, not DNA. In RNA, uracil replaces thymine as the base that pairs with adenine. Therefore, during DNA replication, uracil cannot be used because it is not one of the bases found in DNA.