AP BIOLOGY

Detailed explanation-1: -Duplications. Duplications occur when part of a chromosome is abnormally copied (duplicated). This type of chromosomal change results in extra copies of genetic material from the duplicated segment.

Detailed explanation-2: -In the eukaryotic cell cycle, chromosome duplication occurs during “S phase” (the phase of DNA synthesis) and chromosome segregation occurs during “M phase” (the mitosis phase).

Detailed explanation-3: -The term “duplication” simply means that a part of a chromosome is duplicated, or present in 2 copies. This results in having extra genetic material, even though the total number of chromosomes is usually normal.

Detailed explanation-4: -Duplications. Duplications result from the gain of DNA in a chromosome resulting from unequal crossing over during meiosis (Takahashi et al., 1982; Figure 3).

Detailed explanation-5: -Segmental duplications (SDs) are long DNA sequences that are repeated in a genome and have high sequence identity. In contrast to repetitive elements they are often unique and only sometimes have multiple copies in a genome.