What causes a chromosomal duplication to occur?

• A. Loss of a chromosome segment
• B. Nondisjunction during mitosis
• C. Point mutation in a single nucleotide
• D. Unequal crossing over during meiosis

Answer: (D)

Verified step by step guidance

1. Understand the concept of chromosomal duplication: Chromosomal duplication occurs when a segment of a chromosome is copied and inserted into the genome, resulting in multiple copies of that segment.
2. Learn about meiosis and crossing over: Meiosis is a type of cell division that reduces the chromosome number by half, creating four haploid cells. During meiosis, homologous chromosomes can exchange segments in a process called crossing over.
3. Explore unequal crossing over: Unequal crossing over occurs when homologous chromosomes misalign during meiosis, leading to an unequal exchange of genetic material. This can result in one chromosome gaining extra copies of a segment, causing duplication.
4. Differentiate from other genetic events: Loss of a chromosome segment, nondisjunction, and point mutations are different genetic events. Loss of a segment results in deletion, nondisjunction leads to an abnormal number of chromosomes, and point mutations affect single nucleotides without causing duplication.
5. Recognize the impact of chromosomal duplication: Duplication can lead to genetic variation and evolution, but it can also cause genetic disorders if the duplicated segment disrupts normal gene function.