Final answer:
Complete molar pregnancies typically have a diploid karyotype with all paternal chromosomes, while partial molar pregnancies have a triploid karyotype, often due to an egg being fertilized by two sperm.
Step-by-step explanation:
The karyotype of a complete and partial molar pregnancy differs primarily in the chromosomal composition that leads to these conditions. In a complete molar pregnancy, there is usually a diploid set of chromosomes, all of which are paternal in origin. This means there are 46 chromosomes, but no maternal chromosomes are present, as the egg's genetic material is lost or inactive. In contrast, a partial molar pregnancy often involves a triploid karyotype, which means there are 69 chromosomes in total. This can happen when two sperm fertilize a single egg, leading to an extra set of paternal chromosomes.
A karyogram, or the photographic image of a karyotype, can help identify these conditions by analyzing the number and appearance of an individual's chromosomes, including the size, banding patterns, and centromere position. In cases of molar pregnancies, a karyogram is a crucial diagnostic tool to determine the exact chromosomal differences that have occurred.