Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Problem:Passage: To begin mitosis, the DNA in the nucleus wraps around proteins to form chromosomes . Each organism has a unique number of chromosomes. In human cells, our DNA is divided up into 23 pairs of chromosomes. Replicated DNA forms a chromosome made from two identical sister chromatids , forming an "X" shaped molecule ( Figure below ). The two chromatids are held together on the chromosome by the centromere . The centromere is also where spindle fiber microtubules attach during mitosis. The spindles separate sister chromatids from each other. Answer: chromosomes
Solution:
What forms when the dna in the nucleus wraps around proteins?