1. MUTATIONS
Where, when, why, and how?

2. Basic facts
A mutation is a change in the genetic code (DNA) of an organism
These changes can be to only one nucleotide or to a whole chromosome
Some mutations occur naturally, while others can brought on by exposure to something
A change in the genetic code can change the amino acid sequence, resulting in a change in the proteins

3. Types of mutations Nucleotide: TTGTCGTATTG Leucine – Serine – Tyrosine
Substitution (aka point mutation) = one base changes into another, may or may not change the amino acid
Ex: TTGTCATATTG Leucine – Serine – Tyrosine
TTGTCGTATTG Leucine – Serine – Tyrosine

4. Types of mutations TTGGTCATATTG Leucine – Valine – Isoleucine
Frameshift:
Insertion = a base is inserted into the DNA code, often changes the amino acid sequence
Ex: TTGTCATATTG Leucine – Serine – Tyrosine
TTGGTCATATTG Leucine – Valine – Isoleucine
Deletion = a base is removed from the DNA
sequence, often changes the amino acid sequence
-Ex: TTGTCATATTG Leucine – Serine – Tyrosine
TTTCATATTG Phenylalanine – Histidine - Isoleucine

5. Types of mutations Chromosomal: affecting parts of chromosomes
Deletion = part is removed
Duplication = a part is repeated
Inversion = a part is turned upside-down
Insertion = a part is added in from another chromosome
Translocation = a part is switched to another part of that or another chromosome

7. Types of mutations
Other mutations can occur during the formation of reproductive cells (sperm and egg)
When chromosomes don’t separate correctly, the resulting gametes may have more or fewer chromosomes than they’re supposed to
This results in the child having more or fewer than 46 chromosomes

8. Why do mutations occur? Natural reasons:
Enzymes like DNA polymerase make a mistake when replicating DNA
Enzymes like RNA polymerase make a mistake when copying DNA message
Cell age

9. Why do mutations occur? Induced:
Exposure to radioactivity (uranium, etc.)
Exposure to UV light
Contact with carcinogens (cancer-causing chemicals)
Viral infection

10. How do mutations affect us?
Sometimes they don’t have any effect
Sometimes they are bad and sometimes they are advantageous

11. Bad effects Can cause genetic disorders and diseases Ex:
Sickle cell anemia
Down Syndrome
Cancer

12. Good effects Increases genetic variation in the gene pool
Can give the person an advantage or protect them from disease
Ex:
Sickle Cell Anemia (prevents getting malaria)
CCR5 gene mutation (prevents from getting AIDS)
Aging associated genes (long life span)

13. How do we detect mutations?
Genetic testing such as DNA sequencing can detect changes in the nucleotides
Chromosomal mutations are detected through the use of karyotypes.

14. Karyotype Chromosomes from the person’s cell are photographed
Then the pictures are cut out and the chromosome pairs are matched up
More or fewer than 46 indicates a mutation