1. Be familiar with the term nondisjunction.
Define the word nondisjunction on a post-it note.
You must utilize your brain and/or the text book, not your technology.

2. Can you spot the differences?
GAME
TIME!
Can you spot the differences?

7. How can we look at chromosomes?
We look at chromosomes in something called a karyotype.
A karyotype is an organized profile of a persons chromosomes.

8. ¿¿Qué es un cariotipo ??
A karyotype is simply a picture of a person's chromosomes.
In order to get this picture, the chromosomes are isolated, stained, and examined under the microscope. Most often, this is done using the chromosomes in the white blood cells.
A picture of the chromosomes is taken through the microscope.
Then, the picture of the chromosomes is cut up and rearranged by the chromosome’s size.
The chromosomes are lined up from largest to smallest. A trained cytogeneticist can look for missing or extra pieces of chromosome.

9. HOMOLOGOUS CHROMOSOMES
What do we call these?

10. What’s a homologous chromosome?
Have genes for the same trait at the same location.

11. Normally, humans have 46 chromosomes in each cell
Chromosome Numbers
Normally, humans have 46 chromosomes in each cell
23 from our mother 
23 from our father 
Knowing these numbers is essential for scientists to tell if someone has a genetic disorder.

12. It is possible for a person to have more or less than 46 chromosomes
More Numbers
Since humans have 46 chromosomes that means they have 23 pairs of homologous chromosomes.
It is possible for a person to have more or less than 46 chromosomes
This results in a genetic disorder

13. What can looking at chromosomes tell us?
Whether or not an individual has a genetic disorder.
If there is a possibility that an unborn child could have a genetic disorder.
If an unborn child will be male or female.

14. Discussion Points
Would you want to know if your baby had a genetic disorder?
What would be the benefits?
What would be the consequences?

15. Karyotypes of Genetic Disorders

17. How do you end up with more or less chromosomes?
Nondisjunction This happens when two chromosomes do not properly separate during the formation of gamates ( eggs and sperm).

18. Trisomy 21
1 in every 691 births

19. Trisomy 21

20. Trisomy 21 (Down Syndrome)
Characteristics
Deep creases across palms of hands
Upward slant to eyes
Heart defects
Poor vision

21. Trisomy 21 (Down Syndrome)

22. Turner Syndrome
1 in every 2,500 female babies

23. Normal Female
Turner Syndrome

24. Characteristics Turner Syndrome Short Stature Infertile ‘Webbed’ neck
Heart Defects-constricted aorta

25. Turner Syndrome

26. Klinefelter’s Syndrome
1 in 500 to 1,000 newborn males

27. Klinefelter’s Syndrome

28. Klinefelter’s Syndrome
Characteristics
Occurs only in males
Long Arms and Legs
Weak Bones
Low Testosterone
Enlarged breast tissue

29. Klinefelter’s Syndrome

30. Jacob’s Syndrome (Supermale)

31. Jacob’s Syndrome (Supermale)

32. Triple X Syndrome (Superfemale)

33. Triple X Syndrome (Superfemale)

34. Karyotype Practice
A. Male
B. Female
2. A. Normal
B. Abnormal

35. A. Male B. Female
A. Normal
B. Abnormal
3. A. Turner’s
B. Klinefelter’s
C. Down’s
D. Super female

36. A. Male B. Female
A. Normal
B. Abnormal
3. A. Super female
B. Turner’s
C. Down’s
D. Klinefelter’s

37. A. Male B. Female
A. Normal
B. Abnormal
3. A. Down’s
B. Super female
C. Cri du chat
D. Turner’s
E. None of the above

38. A. Normal
B. Abnormal
A. Down’s
B. Klinefelter’s
C. Turner’s
D. Normal
3. A. Male B. Female
4. The genotype is:
A. XXX B. XO
C. XXY D. Normal

39. A. Normal
B. Turner’s
C. Klinefelter’s
D. super female
E. Down’s Syndrome
2. This karyotype shows a:
A. sex – chromosome disorder
B. Autosomal disorder
C. Normal karyotype

40. A. Male B. Female
A. Normal B. Abnormal

41. DNA Banding a.k.a DNA Fingerprinting
Who Done It?
Who are the Parents?

42. What is DNA banding?
A technique for comparing the nucleotide sequences of fragments of DNA from different sources. DNA fingerprinting is often used to provide evidence in criminal law cases or determine the relatedness of two or more individuals.

43. What is DNA Profiling?
A technique used by scientists to distinguish between individuals of the same species using only samples of their DNA 43

44. Who Invented it?
The process of DNA fingerprinting was invented by Alec Jeffreys at the University of Leicester in 1985.
He was knighted in 44

45. Stages of DNA Profiling
Cells are broken down
to release DNA
If only a small amount of DNA is available it can be amplified using the polymerase chain reaction (PCR) 45

46. Stages of DNA Profiling
Step 2:
The DNA is cut into fragments using restriction enzymes.
Each restriction enzyme cuts DNA at a specific base sequence. 46

47. Stages of DNA Profiling
The sections of DNA that are cut out are called restriction fragments.
This yields thousands of restriction fragments of all different sizes because the base sequences being cut may be far apart (long fragment) or close together (short fragment). 47

48. Stages of DNA Profiling
Fragments are separated on the basis of size using a process called gel electrophoresis.
DNA fragments are injected into wells and an electric current is applied along the gel. 48

49. Stages of DNA Profiling
DNA is negatively charged so it is attracted to the positive end of the gel.
The shorter DNA fragments move faster than the longer fragments.
DNA is separated on basis of size. 49

50. Stages of DNA Profiling
A radioactive material is added which combines with the DNA fragments to produce a fluorescent image.
A photographic copy of the DNA bands is obtained. 50

51. Stages of DNA Profiling
The pattern of fragment distribution is then analysed. 51

52. Uses of DNA Profiling
DNA profiling is used to solve crimes and medical problems 52

53. Crime
Forensic science is the use of scientific knowledge in legal situations.
The DNA profile of each individual is highly specific.
The chances of two people having exactly the same DNA profile is 30,000 million to 1 (except for identical twins). 53

54. Biological materials used for DNA profiling
Blood
Hair
Saliva
Semen
Body tissue cells
DNA samples have been obtained from vaginal cells transferred to the outside of a condom during sexual intercourse. 54

55. DNA Profiling can solve crimes
The pattern of the DNA profile is then compared with those of the victim and the suspect.
If the profile matches the suspect it provides strong evidence that the suspect was present at the crime scene (NB:it does not prove they committed the crime).
If the profile doesn’t match the suspect then that suspect may be eliminated from the enquiry. 55

56. Example A violent murder occurred.
The forensics team retrieved a blood sample from the crime scene.
They prepared DNA profiles of the blood sample, the victim and a suspect as follows: 56

57. Crime Scene
Suspect 1
Suspect 2
Suspect 3

58. Was the suspect at the crime scene?
Suspects Profile
Blood sample from crime scene
Victims profile 58

59. Solving Medical Problems
DNA profiles can be used to determine whether a particular person is the parent of a child.
A childs paternity (father) and maternity(mother) can be determined.
This information can be used in
Paternity suits
Inheritance cases
Immigration cases 59

60. Example: A Paternity Test
By comparing the DNA profile of a
mother and her child it is possible to
identify DNA fragments in the child
which are absent from the mother and
must therefore have been inherited
from the biological father. 60

61. Is this man the father of the child?
Mother
Child
Man 61

62. Famous cases
In 2002 Elizabeth Hurley used DNA profiling to prove that Steve Bing was the father
of her child Damien 62

63. Famous Cases
Colin Pitchfork was the first criminal caught based on DNA fingerprinting evidence.
He was arrested in for the rape and murder of two girls and was sentenced in 1988. 63

64. Famous Cases
O.J. Simpson was cleared of a double murder charge in 1994 which relied heavily on DNA evidence.
This case highlighted lab difficulties. 64

66. DNA Banding
Person

67. DNA from crime scene
Suspects’ DNA
Person