2. HUMAN GENETICS
What can go wrong?
Chromosome Gene Mutations Mutations

3. Chromosomal Abnormalities
1 infant in 200 newborns has a chromosomal abnormality
28% of first trimester miscarriages have a chromosomal abnormality
Abnormalities in larger chromosomes don’t usually survive

4. MUTATION BENEFICIAL HARMFUL
A change in the DNA code of an organism is called a ______________________
Mutations can be
_______________ OR ______________
MUTATION
BENEFICIAL
HARMFUL

5. BENEFICIAL MUTATIONS Help an organism survive and reproduce
Provide variation in population for natural selection to act upon
Ex: White fur if you live in a snowy place
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6. HARMFUL MUTATIONS LETHAL Can result in death =___________
(even before birth)
Cause a genetic disorder
Cause cancer

7. SOMATIC CELL MUTATIONS
If the change happens in a BODY CELL (lung, liver, brain, muscle, etc.)
= ______________________
Somatic cell mutations can: ______________________
______________________
_____________
Somatic cell mutation
Cause cancer
Make cell not able to function
Kill cell
BUT won’t be passed on to offspring

8. GERM CELL MUTATION Germ cell mutation
If the change happens in Gametes (sperm & eggs)
= _______________________
Germ cell mutation
Can be passed on to offspring

9. What can go wrong? GENE ___________Mutations-
Changes in an individual gene
__________________Mutations
Changes in the number of chromosomes
CHROMOSOME

10. ADDITION A T T C G A G C T A T T C G T A A G C T
Putting in extra bases during copying
A T T C G A G C T
A T T C G T A A G C T

11. SUBSTITUTION A T T C G A T T G C T Changes one base for another
A T T C G A G C T
A T T C G A T T G C T

12. DELETION Piece of whole chromosome is lost
________________________________________
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13. DUPLICATION Piece of DNA is copied too many times
________________________________________________
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14. INVERSION Segment flips and reads backwards
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15. TRANSLOCATION
Segment breaks off and joins a different non-homologous chromosome
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16. DNA RNA PROTEIN   GENE MUTATIONS
Changes in the DNA code of a single gene
DNA 
RNA
PROTEIN 
___________ ____________ ______________________

17. PROTEINS are built from AMINO ACID subunits
Image by: Riedell

18. Each group of 3 nitrogen bases codes for a different amino acid
There are 20 different AMINO ACIDS
used by cells to make PROTEINS

19. Proteins are made by joining amino acids together in long chains
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20. Harmful Gene Mutations
Point mutations –
change a _________ base in DNA code
Frame shift mutations change _____________ bases in code
SINGLE
MULTIPLE

21. FRAME SHIFT MUTATIONS Caused by changes in code that are NOT multiples of
DNA message is read in groups of three nitrogen bases

22. ____________________ DELETION theatcatranandran _____________________
FRAME SHIFT MUTATIONS
thefatcatranandran
____________________
DELETION
theatcatranandran
_____________________
the fat cat ran and ran
the atc atr ana ndr an

23. FRAME SHIFT MUTATIONS at beginning of gene are more damaging than those at end because more of gene is changed
thefatcatranandran
____________________
DELETION near front
theatcatranandran
_____________________
DELETION near end
the fat cat ran and ran
the atc atr ana ndr an
thefatcatranandrn

24. HUMAN GENETIC DISORDERS
Caused by Gene Mutations

25. DELETION Piece of whole chromosome is lost
________________________________________
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26. Cri-du-chat (Cat cry) (5p-)
1 in 50,000 births
More common in girls

27. Mewing cry in infancy
Missing piece of number 5
Mental retardation
50% have heart defects

28. Prader-Willi Syndrome
Deletion in chromosome 15
Feeding problems: poor weight gain in infancy, won’t eat
Ages 1-6 excessive, rapid weight gain
Under developed sex organs
Mild to moderate retardation
Obsession with food
Complications from problems associated with obesity (heart attack, high blood pressure, diabetes)

29. Prader-Willi syndrome
Victor at age Victor at age 2

30. SUBSTITUTION A T T C T A G C T Changes one base for another
A T T C G A G C T
A T T C T A G C T

31. A gene that is flipped and reads backwards will not work.
A gene that is moved to
another chromosome
will not separate from
its partner during meiosis.
One cell can get 2 copies
of gene, one cell gets none.

32. SICKLE CELL ANEMIA CAUSE: (autosomal recessive)
A changed to T (glu to val)
gene on chromosome #11
that codes for part of
hemoglobin protein
(carries oxygen in blood)

33. SICKLE CELL ANEMIA SYMPTOMS:
Sickle shaped Red Blood Cells in hh persons
Circulatory problems
Loss of blood cells (anemia)
Organ damage
DEATH

34. SICKLE CELL ANEMIA More common in African Americans 1 in 500 = hh
1 in 10 = Hh carriers for gene
Hh persons have Sickle cell TRAIT
make some normal RBC’s’ ; some sickled cells

35. Having two copies of gene (hh) makes a person sick
Having one copy (Hh)- gives person resistance to MALARIA

36. DELETION Piece of DNA code for one gene is lost
________________________________________
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37. Duchenne Muscular Dystrophy
CAUSE:
(X linked recessive)
DELETION in gene that codes for a muscle protein

38. Duchenne Muscular Dystrophy (DMD)
SYMPTOMS:
1 in 3500 male births
Appears before age 5
Progressive muscle weakening
Most in wheelchair by age 13
Eventually lethal

39. DUPLICATION Piece of DNA is copied too many times
________________________________________________
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40. FRAME SHIFT MUTATIONS Changes multiple bases in code
thefatcatranandran
____________________
DUPLICATION
thefatcatranandandandandran
___________________________
the fat cat ran and ran
the fat cat ran and and and ran

41. HUNTINGTON’S CAUSE: Autosomal dominant 40-100 CAG Repeats
at end of gene on
chromosome 4

42. HUNTINGTON’S SYMPTOMS: Seen in both males and females
Degenerative brain disorder
Symptoms appear
age 30-40
(Usually after having children)
Lose ability to walk, think, talk, reason
50/50 chance of passing it to child
SYMPTOMS: Seen in both
males and females

43. Until now people didn’t know they had the gene, until after they had already had children.
Now there is a test to tell if you have the gene before symptoms appear.
Would you want to know if there is NO cure?

44. Genetic disorders can be carried on:
AUTOSOMES
= ________________
SEX CHROMOSOMES
= _______________
AUTOSOMAL
SEX-LINKED

45. OTHER GENETIC DISEASES
AUTOSOMAL RECESSIVE
Phenylketonuria
Cystic fibrosis
Albinism
X-LINKED RECESSIVE
Color blindness
Hemophilia
Muscular dystrophy
AUTOSOMAL DOMINANT
Achondroplasia (Dwarfism)
Huntington’s

46. HEMOPHILIA
CAUSE:
change in gene on X chromosome that codes for blood clotting protein
SYMPTOMS:
More common in males
Internal and external bleeding Can result in death transfusions/hospitalization required frequently to stop bleeding

47. ACHONDROPLASIA (Dwarfism)
CAUSE: (Autosomal Dominant on chromosome 4) Most are new mutations in egg or sperm cell, but it can be inherited from parent with gene
1 in 20,000 births
200,000 “little people” worldwide
One of oldest known – seen in Egyptian art
Normal size torso; short arms and legs
Problem with way cartilage changes to bone as bones grow

48. COLOR BLINDNESS CAUSE: X linked recessive
Mutation in gene on X chromosome
SYMPTOMS: More common in males (8% of males are colorblind)
Can’t distinguish certain colors Most common = red/green

49. Cystic Fibrosis
Mutation in gene on chromosome 7 that codes for protein in membrane that transports chloride ions

50. Cystic Fibrosis Autosomal recessive
Symptoms: More common in Caucasians
Make extra thick mucous in lungs and pancreas which leads to respiratory and digestive complications
Salty skin is clue

51. Phenylketonuria (PKU)
CAUSE: Mutation in gene for enzyme that changes the amino acid phenylalanine into tyrosine
Build up causes brain damage
ALL babies have blood test for PKU when born before leaving hospital
Treatment: Diet low in phenylalanine can extend life and prevent retardation * Nutri-sweet warning

52. All “SUGAR-FREE” foods have a warning label
* PHENYLKETONURICS: Contains phenylalanine
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54. HUMAN GENETICS What can go wrong? Chromosome Mutations
Changes in chromosome number

55. Missing chromosomes (monosomy) EX: Turner’s syndrome - X0
Changes in chromosome number
____________________________
Missing chromosomes (monosomy)
EX: Turner’s syndrome - X0
Extra chromosomes (trisomy)
EX: Down’s syndrome – 3 #21’s
Kleinfelter’s syndrome- XXy

56. NON-DISJUNCTION
A homologous pair sticks together and doesn’t separate at MEIOSIS.
One cell gets 2 copies of
the chromosome the
other cell gets none.

57. Normal Meiosis

58. Nondisjunction

59. Nondisjunction Chromosomes don’t separate at anaphase
Cell gets 2 copies of a chromosome OR none
After fertilization new baby gets 3 of each chromosome (trisomy) or only 1 copy of each (monosomy)

60. Normal division
Non-disjunction

61. Human Abnormalities Caused by Non-Disjunction
Down’s syndrome
Patau syndrome
Kleinfelter syndrome
Turner’s syndrome
Xyy

62. Down’s syndrome (trisomy 21)

63. Down’s syndrome (trisomy 21)
1 in 660 births
Similar facial features
Slanted eyes
Protruding tongue

64. Down’s syndrome (trisomy 21)
Simian line on palm

65. Down’s syndrome (trisomy 21)
Most common chromosomal abnormality
50% have heart defects that need surgery to repair
Mental retardation
Risk increases with age of mom

66. Patau syndrome (trisomy 13)

67. Patau syndrome (trisomy 13)
Can be traced back 300 years in literature
1st identified as a chromosomal cause in 1960
1 in 7000 births (rare)

68. Patau syndrome (trisomy 13)
Cleft lip & palate
Eye abnormalities
(too small or missing)

69. Patau syndrome (trisomy 13)
Low set ears
Polydactyly

70. Turner’s syndrome (monosomy)

71. Turner’s syndrome XO 1 in 5000 births Female = XO Small size
Slightly decreased intelligence
35% have heart abnormalities
Hearing loss common
Broad chest
Undeveloped ovaries/can’t have children

72. Kleinfelter syndrome Xxy (trisomy)

73. Kleinfelter syndrome 1 in 1000 births Male = XXy
Average to slight decrease in intelligence
Small testes/
can’t have children
Usually not discovered until puberty when don’t mature like peers

74. Xyy syndrome Xyy males Taller Average intelligence
Some study show increased learning disabilities
Most lead normal lives