Final answer:
A Robertsonian translocation takes place when the short arms of two nonhomologous acrocentric chromosomes are lost, resulting in their fusion into one larger chromosome.
Step-by-step explanation:
A Robertsonian translocation occurs when two nonhomologous acrocentric chromosomes lose their short arms and fuse to form a large single chromosome. This type of translocation is distinct from a reciprocal translocation, which involves the exchange of segments between nonhomologous chromosomes without loss of genetic material. Robertsonian translocations can have significant genetic consequences and are associated with certain disorders, such as Down syndrome when involving chromosome 21.