2. Gene Mutations
• Mutation – change in the genetic material
of a cell
• Point mutations
– Changes in one or a few nucleotides
– Insertions, deletions, substitutions
• Frameshift mutations
– Reading frame of the genetic code is shifted
– Insertions and deletions are examples
3. Chromosomal Mutations
• Change in the number or structure of
chromosomes
• Can change location of genes on
chromosomes, or the number of copies
of some genes
• Four types are: deletion, duplication,
inversion, and translocation (see page
318)
4. Effects of Mutations
• Chemical or physical agents in the
environment that can alter genetic
material
• Can help or harm organisms, although
most have little or no effect
• Chemical mutagens can include:
pesticides, tobacco smoke, and
pollutants
• Physical mutagens can include: x-rays
and ultraviolet light
5. Example
• Sickle cell anemia (see page 318)
–Caused by point mutation
–Causes red blood cells to change shape
–Sickle-shaped cells interfere with blood
flow and can cause severe problems in
bloodstream
