1. Mutations

2. Any change in the DNA base sequence
What is a mutation?
Any change in the DNA base sequence

3. What are the two different classes of mutations?
Gene Mutations
Chromosomal Mutations

4. What is a gene mutation?
A change in the base sequence of one gene

5. What causes gene mutations?
Errors in DNA replication
Chemicals
UV/X-ray Radiation

6. Types of Gene Mutations
Substitution
Deletion
Insertion
Original DNA Strand

7. Two types of Gene Mutations
Point mutation
A change in ONE nitrogenous base, the overall number of bases stays the same (Substitution)
Frame shift mutation
A change in the number of overall nitrogenous bases in the genetic code (Insertion or Deletion)

8. Substitution Mutation
Substitution – One nitrogenous base is substituted for another.

9. Deletion and Insertion Mutations
Deletion – One or more nitrogenous bases are removed
Insertion – Extra nitrogenous bases are added to the genetic code.

10. Sickle Cell Anemia

11. How does a mutated protein affect a cell?
If the shape of the protein is altered, it MIGHT disrupt its normal activity OR (functioning).

12. What type of mutation is it?

13. How can gene mutations be passed down to future offspring?
ONLY IF THEY OCCUR IN THE SEX CELLS

14. What are some characteristics of gene mutations?
They can be dominant or recessive
They can occur on autosomal chromosomes (pairs 1-22) or sex chromosomes (pair 23)
 People that are heterozygous for a recessive genetic disorder are called carriers
 Carriers have one normal allele and one diseased allele; They do not show symptoms for the disease but may pass the allele to future offspring

15. COLORBLINDNESS:
A SEX-LINKED DISORDER

16. Genetic Diseases caused by gene mutations:
Cystic Fibrosis
Faulty gene produces a
defective protein that does not allow for the proper
removal of mucous lining the cells of the lung and GI
tract.

17. Gene Mutations: Tay-Sachs Disease
Faulty gene produces a defective enzyme
which cannot help remove fat from nerve cells.

18. Sickle-Cell Anemia:
One base is substituted for another and this causes
the production of a distorted hemoglobin molecule
(protein) which cannot function properly.

19. What do these three gene mutations have in common?
They all affect the shape of proteins!! If we change
the shape of proteins (enzymes) they will not
function properly and this will affect our phenotype.

20. How do we trace/identify gene mutations in a population or family?
Pedigree Charts: - A diagram that shows the presence or absence of a particular trait through each generation.
Genetic Testing: Ability to diagnose vulnerabilities to various genetic disorders

21. Recessive Gene Pedigree ChartCc Cc cc

22. A – Dominant Allele; a - Recessiveaa Aa Aa Aa aa aa Aa Aa aa ? aa ?

23. H – Dominant Allele; h - RecessiveHh hh hh Hh Hh hh hh hh hh hh hh hh hh Hh

24. What is a chromosomal mutation?
Any change in the number or structure of chromosomes

25. Chromosome Damage: Part of a chromosome is repeated.
missing.
Reversing a fragment of the
chromosome.
A fragment of one
chromosome attaches to a
nonhomlogous chromosome.

26. Abnormal Numbers of Chromosomes
Polyploidy: Having many sets of chromosomes – 1.5n, 3n, 4n, 5n

27. Abnormal Numbers of Chromosomes
Aneuploidy: The addition or loss of a whole chromosome

28. How do these mutations occur?
NONDISJUNCTION: occurs when homologous
chromosomes or sister chromatids fail to separate during meiosis.

29. Normal Karyotype

30. Trisomy 21 – Down Syndrome

31. Trisomy 18 – Edward’s Syndrome

32. Monosomy X – Turner Syndrome

33. Chrom. #5 deletion: Cri-du-Chat Syndrome

34. Klinefelter’s Syndrome