If one strand of a dna molecule has the sequence of bases 5'-attgca-3', the other complementary strand would have the sequence

3'-taacgt-5´

Explanation:

In the DNA molecule we find pure bases (adenine and guanine) and pyrimidines (cytosine and thymine).

The bases are paired (leaving one base of each type) as follows:

Adenine - Thymine: joined by two hydrogen bonds

Cytosine- Guanine: joined by three hydrogen bridges

If we have a DNA molecule with the base sequence

5'-attgca-3 'the complementary chain will be formed as follows

3'-taacgt-5'.

explanation:

the fossil record extends back to a dog-like ancestor some 55 million years ago, which gave rise to the first horse-like species 55 to 42 million years ago in the genus eohippus.