1. MUTATIONS

2. What is a Mutation? A change in DNA Mutants are NOT
Teenage Mutant Ninja
Turtles or XMen!!!
We are all mutants –
products of the mutations
in all of our ancestors before us

3. How Do Mutations Occur?
During DNA replication when bases are substituted, deleted, or added
During mitosis and/or meiosis when chromosomes don’t divide properly
During crossing over when chromatids “get lost” instead of being incorporated into its homolog’s DNA

4. Aging causes mutations when segments of DNA are degraded (telomeres)
Exposure to chemicals in the environment called mutagens (such as UV radiation, Xrays, some food dyes)

5. Somatic vs. Germ Cell Mutations Are Mutations Inherited?
Somatic mutations affect cells of the body, such as skin, muscle, etc.
Somatic mutations can not be passed to offspring
Germ cells are cells that divide to make gametes
Germ cell mutations are passed to offspring

6. An Example of Germ Cell Mutation
Queen Victoria had a germ cell mutation in cells of the ovary
The mutation was in a gene that makes a protein for blood to clot
She passed this mutation on to some of her children and they had hemophilia

9. Gamete cells mutations can result in genetic disorders.
If the parent survives with the disorder, it can be passed to another generation.

10. An Example of Somatic Mutation
UV radiation from the sun can mutate DNA in skin cells and cause cancer
That cancer is not inherited

11. Gene vs. Chromosome Mutations
Gene mutations affect one gene and therefore one protein (or polypeptide)
Chromosome mutations affect a large part of a chromosome and all of the genes on that section of chromosome

12. Gene Mutations Can occur during DNA replication
They are often point mutations, which affect a small number of bases or sometimes just one base pair

13. Types of Point Mutations
Insertion (Addition)–one (or a few) bases is (are) inserted
Deletion – one (or a few) base is (are) deleted
Substitution – one base is substituted with another one

15. Deletion and Insertion Mutations Can Cause a Frameshift

16. Sickle Cell

17. The mutation is in the gene for hemoglobin
Malformed hemoglobin molecules cause red blood cells to “sickle”

18. Red blood cells cause blood clots, which damage the kidneys and liver
Severity varies from person to person
Shortened life span (45 years is average)
Pain due to blood clots
Fatigue from lack of oxygen

21. Sickle Cell is Found in Certain Ancestral Groups

23. Sickle cell evolved as a protection against malaria
People with one sickle cell gene and one healthy gene don’t have sickle cell or get malaria!

24. Cystic Fibrosis
Deletion in a transport protein that allows Cl- to enter and exit cells
Causes thick mucus to build up in lungs, which causes repeated lung infections
Mucus clogs up pancreatic duct so food isn’t digested
Mucus causes intestinal blockage

25. Breathing treatments can loosen mucus in lungs to increase lung function and decrease chance of infection

26. Treated with antibiotics for
infections
Use oral enzymes to digest food
(increase in food intake to make
up for undigested food)
The mutation is found here 
on chromosome 7

27. CF occurs in all ancestral backgrounds and is the most common fatal genetic disorder (about 1 in every 20 people carries the gene)
Severity of disease varies from person to person and they die from a respiratory infection or lung failure

29. Huntington’s Named after Dr. George Huntington who first described it
Caused by an insertion
mutation (CAG is
repeated)
Nancy Wexler

30. Causes jerky and uncontrolled movements
Slurred speech
Loss of memory
Symptoms progress and get worse with time; caused by degeneration of nerve cells
Symptoms usually appear between the ages of 35-40, but can be earlier

31. Found in all major ethnic groups
Death is usually from pneumonia or choking
Can live years after the onset of the symptoms; some die earlier

32. Severe Combined Immunodeficiency (SCID)
Causes an absence in white blood cells that function in immunity
Very susceptible to life-threatening infections
Different types of SCID with the most common (and most life threatening) type found only in males

33. Nondisjunction Mutations (Type of Chromosome Mutation)
Occur when chromosomes fail to separate during meiosis
Results in a cell with an extra chromosome or a chromosome missing
The person wouldn’t have 46 chromosomes, but 45 or 47

34. An Example of a Nondisjunction Mutation Down’s
Named after Dr. Down that first described it
Caused by 3 copies of the 21st chromosome (trisomy 21)
Causes heart defects, mental retardation, unclear speech, rounded face, almond shaped eyes, poor muscle tone, fold in the eyelid

35. Notice the 3 21st chromosomes

37. Another Example of Nondisjunction Klinefelter’s
An extra X chromosome (XXY) in males
Usually sterile, some have enlarged breasts, delayed learning, may be tall and thin, symptoms vary and may be undetectable

38. Notice the 3 sex chromosomes

39. How Klinefelter’s Occurs

40. And Another Example of Nondisjunction Turner’s
Have 1 X chromosome (XO) - females
About 98% of fetuses with Turner’s are spontaneously aborted (miscarried)
Short, swelling of hands and feet, sterile, and other symptoms vary from person to person