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: -Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains a gene.

Detailed explanation-3: -Duplication produces an extra copy of all or part of a chromosome. Inversion reverses the direction of parts of a chromosome. Translocation occurs when part of one chromosome breaks off and attaches to another. Some mutations arise from mutagens, chemical or physical agents in the environment.

Detailed explanation-4: -The addition of an extra chromosome usually occurs spontaneously during conception. The cause of this is unknown and prevention is not possible. The most important risk factor for trisomy conditions is maternal age. Women in their late 30s and 40s have a higher chance of trisomy conditions occurring.

Detailed explanation-5: -Gene duplication can occur by several mechanisms, including whole-genome duplication (WGD) and single gene duplication. Single gene duplication includes four types, tandem (TD), proximal (PD), retrotransposed (RD), DNA-transposed (DD) and dispersed duplication (DSD) (Freeling, 2009; Hahn, 2009; Wang et al., 2012b).