Advanced Placement (AP) Biology Practice Exam

What does translocation involve in chromosome structure?

1. Moving a segment from one chromosome to another

2. Coiling a chromosome into a Barr body

3. Duplicating a pair of chromosomes

4. Removing part of a chromosome

The correct answer is: Moving a segment from one chromosome to another

Translocation in chromosome structure specifically refers to the process where a segment of one chromosome breaks off and attaches to another chromosome. This is a significant mechanism in genetics as it can lead to various chromosomal disorders or contribute to the genetic diversity within a population. During translocation, the DNA sequences involved can swap places between the two chromosomes, potentially disrupting gene function or leading to the formation of new gene combinations. There are different types of translocations, such as reciprocal translocations (where segments are exchanged between chromosomes) and non-reciprocal translocations (where a segment moves from one chromosome to another without an exchange happening). This process contrasts with other options that do not accurately describe translocation. For instance, the coiling of a chromosome into a Barr body relates to the inactivation of one of the X chromosomes in females, which follows a distinct biological mechanism rather than involving translocation. Similarly, duplicating a pair of chromosomes refers to replication, which is necessary for cell division, and removing part of a chromosome generally describes deletions rather than the translocation process.