1. Human Genetic Mutations

2. 2 Main Types of Mutations
1.) Chromosomal Mutations
2.) Gene Mutations

3. What are chromosomes?
Humans have 23 pairs of chromosomes, with one chromosome from each parent.
The chromosomes are coiled up DNA.
Under normal conditions all of the chromosomes are inherited in tact.
This is a normal karyotype of human chromosomes. A karyotype is a picture of chromosomes lined up to look at and compare.

4. 5 Types
Deletion
Duplication
Inversion
Translocation
NonDisjunction

5. One or more genes are removed
Chromosomal Deletion
One or more genes are removed
Causes:
Wolf-Hirschhorn syndrome (severe mental retardation)
cri du chat syndrome (mewing sounds, mental retardation)

6. Chromosomal Duplication
A segment of genes is copied twice and added to the chromosome
Causes:
Charcot–Marie–Tooth disease
(high arched foot, claw feet, confined to a wheelchair)

7. Chromosomal Inversion
a segment of genes flip end-to-end on the chromosome
Causes:
Four-Ring Syndrome
(cleft pallate, club feet, testes don’t descend)

8. Chromosomal Translocation
Material is swapped with another chromosome
Causes:
Burkitt’s Lymphoma
(cancer of the lymph nodes, in children)

9. Nondisjunction Chromosomes FAIL TO SEPARATE during meiosis
Meiosis I Nondisjunction
Meiosis II Nondisjunction

10. Nondisjunction
Produces gametes (and therefore a baby) with one missing chromosome or one extra chromosome

11. Nondisjunction (in Meiosis II)

12. Fertilization

13. Nondisjunction
Every cell in that baby’s body will have __ copies of this chromosome instead of___.
This condition is called ____________.
Trisomy 21 = Individual has _____ copies of chromosome # ________

14. Nondisjunction
Every cell in that baby’s body will have 3 copies of this chromosome instead of 2.
This condition is called __________.
Trisomy 21 = Individual has _____ copies of chromosome # ________

15. Nondisjunction
Every cell in that baby’s body will have 3 copies of this chromosome instead of 2.
This condition is called TRISOMY
Trisomy 21 = Individual has __ copies of chromosome # ____.

16. Nondisjunction
Every cell in that baby’s body will have 3 copies of this chromosome instead of 2.
This condition is called TRISOMY
Trisomy 21 = Individual has 3 copies of chromosome # 21.

17. Trisomy 21 - Down Syndrome

18. Gene Mutations: 2 Types
Point Mutation
Frameshift Mutation

19. Point Mutation One base (A, T, C, or G) is substituted for another
Causes: ex. - Sickle-cell anemia
3 Possible Consequences:
nonsense mutations: code for a stop, stops the translation of the protein
missense mutations: code for a different amino acid
silent mutations: code for the same amino acid

20. Example: Sickle Cell Anemia
Normal Red Blood Cell
Sickle Red Blood Cell
Red blood cells shaped like a disc
Hemoglobin (protien) carries oxygen to all parts of the body
Red blood cells form an abnormal crescent shape
Hemoglobin (protein) is abnormally shaped
don't move easily through your blood vessels
form clumps and get stuck in the blood vessels

23. Frameshift Mutations
They shift the “reading frame” of the genetic message.
May change every amino acid that follows the point of the mutation.
Can alter a protein so much that it is unable to perform its normal function.

24. Frameshift Mutation
One or more bases (A, T, C, or G) are added or deleted
Causes: Ex. Cystic Fibrosis
Caused by:
Insertion: adding a base
Deletion: removing a base

25. Frameshift Mutation Original: The fat cat ate the wee rat.
Frame Shift (“a” added):
The fat caa tat eth ewe era t.

26. Causes of Mutations spontaneous occur during DNA replication
Caused by MUTAGENS
physical, ex: radiation from UV rays, X-rays or extreme heat
or chemical (molecules that misplace base pairs or disrupt the helical shape of DNA).

27. Significance of Mutations
Many, if not most, mutations are neutral
Harmful mutations are the cause of genetic diseases
Some mutations, however, are beneficial and lead to a more diverse gene pool.