Question

To be stable, a rearranged chromosome must have which of the following?

A No inverted segments
B A centromere and two telomeres
C A centromere
D A balanced composition (no losses or gains of genetic material)
E A similarly rearranged homolog in the embryo

Answer 1

A stable rearranged chromosome must have a centromere and two telomeres to ensure proper attachment during cell division and protection of chromosome ends. Inversions and translocations can change chromosome structures, requiring looping during meiosis to maintain gene alignment.

Step-by-step explanation:

To be stable, a rearranged chromosome must have a centromere and two telomeres. This is because the centromere is essential for the chromosome to attach to the spindle fibers during cell division, ensuring proper segregation of chromosomes to the daughter cells. The telomeres, which are the repetitive DNA sequences at the ends of chromosomes, protect the chromosome ends from deterioration and from fusion with neighboring chromosomes. Without them, the chromosome stability is compromised.

Structural chromosome rearrangements like inversions and translocations can create significant changes in chromosome structure. In the case of inversions, for instance, a chromosome segment breaks away, flips 180 degrees, and then reattaches. If during meiosis, one chromosome has undergone an inversion and the other has not, the chromosome with the inversion must loop to align correctly with its homolog, ensuring gene alignment and proper recombination.