Dear student,
In a chromosome, the satellite is the structural part that is made by a secondary constriction in the distal end of the chromosome that serve as identifying markers. It can be seen in acrocentric chromosomes in the metaphase. Chromosomes containing satellites are called SAT chromosomes.
Satellites of chromosomes are known to contain repetitive, heterochromatic DNA sequences. In time of the replication of the chromosomes the ends of chromosomal sequences are truncated gradually. As the satellites are nonsense sequences they are lost during replication thus protecting the useful euchromatic DNA towards the core of the chromosome.
Regards.