Question

One strand of a $DNA$ has the following sequence of bases: $ATGCTATTCAG$
In its complementary strand, the number of adenine base units will be______.

Answer 1

Answer: 4

In $DNA$ molecule, adenine $(A)$ always pairs with thymine $(T)$ and cytosine $(C)$ always pairs with guanine $(G)$ .
The sequence of bases in the given strand is: $ATGCTATTCAG$
Thus, the sequence of bases in the complementary strand is: $TACGATAAGTC$
Therefore, there are $4$ adenine base units in the complementary strand.