1. Genetic Mutations
Karyotype: the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

2. Mutations – Changes in DNA that also change the protein produced

3. Causes of Mutation…
Spontaneous: Mistakes in base pairing during DNA replication
Environmental factors: gamma radiation, X rays, ultraviolet light, nuclear radiation, asbestos, cyanide and other mutagens
Mutagen: any agent that can cause a change in DNA

4. Changes can occur without the organism showing an effect
NOTE: sometimes changes DO occur that are not true “mutations” because they are either in non-coding areas of the gene or do not change the protein produced
AUG-ACU-UUU-UGA
Met – Asp – Phe - Stop
AUG-ACU-UUC-UGA

5. Mutations in reproductive cells vs. Mutations in body cells
Changes in reproductive cells:
*code is changed in sperm or egg
*won’t affect the parent, but CAN affect the offspring produced from those altered sex cells
*can be POSITIVE – new, adaptive traits

6. Changes in body cells:
*not passed on to offspring, but can cause MAJOR complications for the individual affected
Ex. Solar radiation – skin cancer
*again process is thought to be the cumulative effect of exposure to mutagens over time…

7. Gene Mutations: changes only ONE base in the code… Substitutions, Insertions, and Deletions
Point mutation: does not affect the length of the code, will just change the amino acid in that position – SUBSTITUTION
Frameshift mutation - does change the length of the code, two types:
INSERTIONS AND DELETIONS
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8. Point mutation: change in single base pair of DNA
Example:
The dog bit the cat
The dog bit the car
AAA TTT CCC GGG
AAA TTA CCC GGG

9. Frameshift mutation: a single base is added or deleted from the DNA strand
Example
The dog bit the cat
Erase the “b” of bit and you get…
The dog itt hec at
AAA TTT CCC GGG
AAA TTC CCG GG

10. Chromosome mutations… Affect Chromosome numbers and shape
1. Mistakes in numbers of chromosomes:
nondisjunction -- members of a pair of homologous chromosomes do not move apart properly
result in offspring that have
Aneuploidy – abnormal chromo number

11. There are four kinds of Chromosomal Mutations
a. deletion – portion of chromosome is missing
b. duplication – portion of chromosome is on the
chromosome twice.
c. inversion – when fragment reattaches to original chromosome but in reverse order
d. translocation – broken fragment attaches to a nonhomologous chromosome

12. Figure 15.13 Alterations of chromosome structure

13. Other stuff
Silent Mutation: frameshift mutation that does not affect the amino acid that is produced; no effect
Missense Mutation: frameshift mutation that results in a changed amino acid
Nonsense Mutation: frameshift mutation that results in an amino acid changing to the “Stop” codon