1. Mutations chapters 8 and 12

2. What Are Mutations? Changes in the nucleotide sequence of DNA
May occur in somatic cells (aren’t passed to offspring)
May occur in gametes (eggs & sperm) and be passed to offspring

3. Types of Mutations

4. Chromosome Mutations May Involve:
Changing the structure of a chromosome
The loss or gain of part of a chromosome

5. CROSSING OVER when the DNA from one chromosome
becomes attached to another chromosome
- usually this occurs on
HOMOLOGOUS CHROMOSOMES during PROPHASE I of MEIOSIS
GENETIC RECOMBINATION- change in the genes or at least the location of genes

6. Chromosome Mutations Five types exist: Deletion Inversion
Translocation
Nondisjunction
Duplication

7. Deletion
Due to breakage
A piece of a chromosome is lost

8. Inversion Chromosome segment breaks off Segment flips around backwards
Segment reattaches

9. Duplication
Occurs when a gene sequence is repeated

10. Translocation Involves two chromosomes that aren’t homologous
Part of one chromosome is transferred to another chromosomes

11. Translocation

12. LAW OF INDEPENDENT ASSORTMENT
during meiosis I- one homologous chromosome travels to each cell. The chromosomes are chosen at random but the odds you get all 23 from the same parent is unlikely.

14. Chromosome Mutation Animation

16. Gene Mutations Change in the nucleotide sequence of a gene
May only involve a single nucleotide
May be due to copying errors, chemicals, viruses, etc.

17. Types of Gene Mutations
Include:
Point Mutations
Substitutions
Insertions
Deletions
Frameshift

18. Point Mutation Change of a single nucleotide
Includes the deletion, insertion, or substitution of ONE nucleotide in a gene

19. Point Mutation
Sickle Cell disease is the result of one nucleotide substitution
Occurs in the hemoglobin gene

20. Frameshift Mutation Inserting or deleting one or more nucleotides
Changes the “reading frame” like changing a sentence
Proteins built incorrectly

21. Frameshift Mutation Original: The fat cat ate the wee rat.
Frame Shift (“a” added):
The fat caa tet hew eer at.

22. Amino Acid Sequence Changed

23. Gene Mutation Animation

24. FYI

25. Nondisjunction Failure of chromosomes to separate during meiosis
Causes gamete to have too many or too few chromosomes
Disorders:
Down Syndrome – three 21st chromosomes
Turner Syndrome – single X chromosome
Klinefelter’s Syndrome – XXY chromosomes

26. Normal Male
2n = 46

27. Normal Female
2n = 46

28. EXAMPLES OF NON-DISJUNCTION

29. Male, Trisomy 21 (Down’s)
2n = 47

30. AN EXTRA COPY OF CHROMOSOME 21 CAUSES DOWN SYNDROME
This condition is called trisomy 21.
Person with this condition suffers from
the Down syndrome.
Characteristic facial features:
Round face
Flattened nose bridge
Small, irregular teeth
Short stature
Heart defects

31. Female Down’s Syndrome

32. Klinefelter’s Syndrome

33. Klinefelter's syndrome, 47, XXY
It is the most common sex chromosome disorder and the second most common condition caused by the presence of extra chromosomes
Symptoms:
Wide hips
Narrow shoulders
Low levels of Testosterone and small testicles / Infertile
Less facial hair

34. Turner’s Syndrome
2n = 45

35. Turner’s Syndrome (X) Common symptoms: Short stature
swelling of the hands and feet
Broad chest and widely spaced nipples
Low hairline
Low-set ears
Reproductive sterility
Increased weight, obesity
Small fingernails
Characteristic facial features
Webbed neck

36. What genetic disorder is this?
They may have never known…