Are there always going to be an equal number of guanine and cytosine in a DNA molecule How about adenine and thymine Why?

Answer:

yes and yes

Explanation:

because the total number of adenine molecule or their pair is the same with that of the number of thymine nucleotides in molecule. This is mainly due to a chemical structure in case of DNA replication the adenine and thymine i.e and the A and T that gets paired up however it might not be exact same in number and there mine an extra C factor in number. This might range to about 0.7-0.8% . This is bec. of the fact that it has never been possible to pair this C with A or T.