1. Chapter 14
- The Human Genome

2. 14-1 Human Heredity
The children in this family have some traits that are similar to their mother’s and some that are similar to their father’s.

3. Can you predict chin shape?
Procedure
Two parents with cleft chins, both heterozygous for cleft chin (Cc), have three children with cleft chins. The parents are sure that their fourth child will not have a cleft chin. Draw a Punnett square to see if this is possible.
Determine the probability that the fourth child will have a cleft chin. _________

4. Human Heredity Human Chromosomes Make us who we are.
This is the genetic information (DNA) which is inside the human cell.

5. To look at these chromosomes, biologists, photograph cells in mitosis.
Mitosis is when the cell nucleus divides and the chromosomes are easier to see.
Biologists then take these photographs and group them together in pairs.
This picture of chromosomes arranged in this way is called a karyotype

6. Karyotype

7. The human body contains 46 chromosomes
23 (sperm)
23 (egg)
Together this forms a diploid zygote
46 total chromosomes

8. Sex Chromosomes and Autosomes
Only 2 of the 46
Determine if someone is male or female
Female: XX
Male: XY
Autosomes
Remaining 44 chromosomes

9. Human Traits Human traits are inherited Gregor Mendel Pedigree chart
A pedigree shows a relationship within a family
A pedigree chart follows one specific trait in a family

11. Cleopatra’s Pedigree Chart

12. Russian Royal Family Pedigree Chart

13. Polygenic Some traits are actually polygenic
Controlled by two or more genes
Shape of your eyes
Shape of your ears
Eye color

14. Other Trait Influences
Environment
Nutrition
Exercise
Your parents might both be 6 feet tall, but if they don’t feed you, you are unlikely to grow to be 6 feet tall.

15. Human Genes Our complete set of genetic information is our genome
Blood Group Genes:
Knowing a person’s blood group is critical because using a wrong blood type could be life threatening Rh
ABO
Are two genes that are part of your blood type

16. Rh Rhesus Monkey” 2 alleles that determine blood type
Rh+ is dominant & Rh- is recessive
A person with 2 positive alleles is Rh+
A person with a positive and a negative allele is RH+
A person with 2 negative alleles is Rh-

17. ABO There are 3 alleles that determine blood type IA, IB and i
Two of these alleles are codominant and one is recessive.
Blood type is dependant upon what the antigens are on the surface of the red blood cells
Type A blood: lAlA, or IAi
Type B blood: IBIB or IBi
Type AB blood: IAIB
Type O blood: ii

19. Based on what you know of blood types; which one of Mr. & Mrs
Based on what you know of blood types; which one of Mr. & Mrs. Lopez’s four kids must have been adopted? _____________

20. Recessive Alleles
Studying genetic disorders have helped us understand how human genes work
Many of these disorders are caused by recessive alleles

21. Phenylketonuria (PKU)
People with this disorder lack the enzyme needed to break down Phenylalanine
Causes:
A build-up of phenylalanine in tissues
Mental retardation
Can be controlled by a special diet
All babies in US are tested for this at birth

22. Tay-Sachs Disease
Nervous system breakdown
Infant death

23. Albinism
Lack of pigment in skin, hair, and eyes

24. Cystic Fibrosis Galactosemia
Excess mucus in lungs, digestive tract, and liver
Susceptibility to infections
Death in early adulthood if not treated
Inability to digest the sugar galactose.
Causes mental retardation, eye and liver damage

25. Cystic Fibrosis

26. Dominant Alleles
Not all genetic disorders are caused by recessive alleles
If you have a dominant allele for a genetic disorder, it will be expressed even if you also have a normal recessive allele
Achondroplasia
Huntington’s disease
Hypercholesterolemia

27. Achondroplasia
Dwarfism

28. Hypercholesterolemia
Huntington’s Disease
Mental deterioration and uncontrollable movements
Hypercholesterolemia
Excess cholesterol in blood
Heart disease

29. Gene Expression
In certain diseases, a small change in the DNA of a single gene affects the structure of a protein, causing a serious genetic disorder
Cystic fibrosis
Sickle cell anemia

30. Sickle Cell Anemia
Abnormal hemoglobin produced because of a single amino acid change in the hemoglobin protein
Causes the RBC’s to deform which causes clogging in the capillaries

33. Sickle Cell Anemia

34. 14-2 Human Chromosomes Sex-Linked Genes
Because the X and Y chromosomes determine sex, genes located here are said to be sex-linked genes
More than 100 sex-linked genetic disorders have been mapped to the X chromosome
Males have just one X chromosome. Thus, all X-linked alleles are expressed in males, even if they are recessive

36. Sex-Linked Genes Genes that are found on the X or Y chromosome.
More genes are found on the X chromosome than the Y

38. Colorblindness
Three genes associated with color vision are found on the X chromosome
Males are more often colorblind because they only have one X chromosome

39. Colorblindness Test

40. Colorblindness
All X-linked alleles are expressed in males even if they are recessive

41. Examples of X-linked Recessive Disorders
Hemophilia: blood-clotting disorder
Duchenne Muscular Dystrophy
Ichtyosis: scaly skin
Norrie Disease: abnormal growth of retina
Rett Syndrome: mental retardation

42. Hemophilia

43. Duchenne Muscular Dystrophy

44. X-Chromosome Inactivation
Females have 2 X chromosomes and males only one. What to do?
In all female cells, one X chromosome is randomly shut off.
This causes some interesting problems if one X chromosome has a mutated gene

45. Chromosomal Disorders
Get too many or too few copies of a chromosome
Caused by non-disjunction during meiosis
Exs. Down’s Syndrome: Trisomy 21
Turner’s Syndrome: X_
Klinefelter’s Syndrome : XXY

46. Down’s Syndrome

47. Turner Syndrome

48. Kleinfelter Syndrome

49. 14-3 Human Molecular Genetics
Human DNA Analysis
Genetic tests are now available for hundreds of disorders.
This can allow prospective parents to determine if they are carrying recessive alleles for a disorder.

50. DNA Fingerprinting DNA is analyzed of by separating it into fragments
This reveals a series of DNA bands of various sizes
A pattern of bands is produced that can be distinguished from any other individual in the world (except for an identical twin).
DNA samples can be obtained from blood, sperm, and hair strands that have tissue at their base.

51. DNA Fingerprinting

52. The Human Genome Project
The Human Genome Project was an attempt to sequence all human DNA
In June 2000, scientists announced that the Human Genome was complete.
There is open availability of nearly all its data.
You can use the Internet to read the latest genome data.

53. Gene Therapy
Gene Therapy is the process of changing the gene that causes a genetic disorder
In gene therapy, an absent or faulty gene is replaced by a normal, working gene
This way, the body can make the correct protein or enzyme it needs, which eliminates the cause of the disorder

54. Gene Therapy

55. Ethical Issues
What will happen to the human species of we could design our bodies? What would be the consequences?
Society will have to develop a thoughtful and ethical consensus of what should and should not be done with the Human Genome.