Changes in Chromosome Structure

This video (No Audio) has an animation of duplication

An inversion alters the position and sequence of the genes so that gene order is reversed within the chromosome.

This video (No Audio) has an animation of inversion

A translocation occurs when a part of one chromosome is transferred to another nonhomologous chromosome. Most translocations are reciprocal. Your textbook describes an example of a form of cancer which resulted where a segment of human chromosome #22 is on chromosome #9 (Philadelphia chromosome).

This video (No Audio) has an animation of translocation

A deletion is the loss of a chromosome region by viral attack, chemicals, irradiation, or other environmental factors. Most are lethal or cause serious disorder.

This video (No Audio) has an animation of deletion

Evolution of Chromosome Structure

Changes in chromosome structure tend to be selected against rather than conserved over evolutionary time. One example of a change in chromosome structure would be that gene regions for the polypeptide chains of hemoglobin have duplicated to produce different hemoglobins with different oxygen transporting efficiencies.

REVIEW: Chromosome structure can be altered by a _____ .
a. deletion
b. duplication
c. inversion
d. translocation
e. all of the above
Answer e