1. Genetics Unit

2. Introduction to Genetics
-Genetics is the study of heredity. -Heredity is how different genes are passed down from parents to children.

3. PHENOTYPE
A phenotype is the expression of an observable physical trait or characteristic of an organism, such as stature or blood type, based on genetic and environmental influences.

4. Examples vs Non-examples
Hair PHENOTYPE Hair-do: not a phenotype
Twins born with A weird girl who fros-out
blonde and red hair her hair

5. Phenotypes Can you think of some examples of phenotypes?
Write down at least 2 examples of phenotypes (traits) in your notes

6. How good are you at judging chimpanzee phenotype?
Which chimps are related?

7. Phenotypes? Yes or no?
Polydactyl

8. Phenotypes? Yes or no?
NO!
Flamingos get their pink color from the food they eat, not their genes!

9. HOMOZYGOUS organism with two identical alleles for the same trait
HOMOZYGOUS organism with two identical alleles for the same trait **root word “homo” = same

10. HETEROZYGOUS organism with two different alleles for the same trait
HETEROZYGOUS organism with two different alleles for the same trait **root word “hetero” = different

11. Homozygous vs. Heterozygous
Two alleles for the “height gene” might be TALL (T) and SHORT (t) A homozygous individual would be TT or tt –two of the same alleles A heterozygous individual would be Tt –two DIFFERENT alleles

12. DOMINANT allele that is expressed when at least one allele is present (TT or Tt = tall) “cover up”

13. RECESSIVE allele that is expressed only when homozygous (no dominant allele) (tt = short)

14. Recessive
Dominant aa
AA or Aa

15. Dominant
Recessive ww
WW or Ww

16. Dimples (D) No dimples (d)
What could AC Slater’s genotype be? Zach’s?
DD or Dd dd

17. My PHENOTYPE is Albino (or no color).
SNOWFLAKE –rare albino gorilla
Albinism
combination of recessive alleles passed from both parents of an individual
prevents the body from making the usual amounts of the pigment melanin
NN = Normal pigmentation (dominant)
Nn = Normal pigmentation
nn = Albinism
About 1 in 17,000 people have some type of albinism, although up to 1 in 75 are carriers.
My PHENOTYPE is Albino (or no color).
My GENOTYPE is nn.

18. TRAIT a characteristic Examples: Plant size, seed color, pod shape

19. GENE (a segment of DNA that controls traits)

20. Above you see chromosomes. The circled area is a gene on chromosome #22. The absence of this gene causes velo-cardio-facial syndrome (VCFS) which may cause ADD and mental illness

21. Breast Cancer and Genes

22. ALLELES
Each gene comes in different forms called alleles, so the gene that controls flower color may come in two alleles: purple and white.

23. ALLELES different forms of a gene

25. The combination of the two alleles for a given gene
Genotype
The combination of the two alleles for a given gene

26. MENDEL’S EXPERIMENTS

27. GREGOR MENDEL The “father” of Genetics Lived from 1822-1884
Austrian Monk
Published his work in 1866, but no one took him seriously until 1900.
Studied Pea Plants!

28. Mendel experimented with 7 different characteristics

29. GENES
Each feature of the pea plants is controlled by a gene. It may have a gene that controls its color, another size for and another for shape.

30. Monohybrid cross.
First, Mendel kept all the traits the same except for _one___. This is a called a __monohybrid___cross___ ________
One trait disappeared in the _F1_______
It reappear in the F2 in a ratio of 3:1_____

31. Dihybrid Cross
Next, Mendel controlled all traits except for __2__. He called this a _dihybrid cross_____
Again, two traits disappeared in the F1
They reappeared in the F2 in a ratio of 9:3:3:1

32. Mendel’s Principles of Inheritance
Inherited traits are transmitted by genes which occur in alternate forms called alleles
Principle of Dominance - when 2 forms of the same gene are present the dominant allele is expressed
Principle of Segregation - in meiosis two alleles separate so that each gamete receives only one form of the gene
Principle of Independent Assortment - each trait is inherited independent of other traits (chance)

33. If we saw an organism that had round seeds (round is dominant), how could we figure out what its genotype is?

34. A cross between an unknown and a homozygous recessive
Test Cross
A cross between an unknown and a homozygous recessive

35. Example of a Test Cross
Unknown

36. Incomplete Dominance
When a combination of the dominant and recessive creates a new phenotype. RR = red, rr = white, and Rr = pink

37. Incomplete Dominance RR Rr rr

38. When both traits are expressed equally. Example: AB blood type
Co-dominance
When both traits are expressed equally. Example: AB blood type

39. a trait that is found on either the X or Y chromosome
Sex Linked Trait
a trait that is found on either the X or Y chromosome

40. Hemophilia is an example of a sex linked trait.

41. a disease where your blood doesn’t clot.
Hemophilia
a disease where your blood doesn’t clot.

42. Hemophilia only occurs when all of the X chromosomes have a copy of the recessive gene.

45. SICKLE CELL ANEMIA

47. Why would African American’s be so much more likely to have Sickle Cell?

49. chart that shows the relationships within a family
PEDIGREE
chart that shows the relationships within a family

51. Pedigree Basics
Males are squares, females are circles, and unborn babies are triangles or octagons
Shaded figures represent individuals with the trait, a carrier could be 1/2 shaded
Generations are numbered with roman numerals (I, II, II, IV) from top to bottom
People within generations are numbered (1,2,3) from left to right

52. ANTIBODY
a protein produced by white blood cells in the body in response to the presence of an antigen, for example, a bacterium or virus

53. ANTIGEN
a substance, usually a protein, on the surface of a cell or bacterium that stimulates the production of an antibody

54. Blood Groups Blood group A
You have A antigens on the surface of your red blood cells and B antibodies in your blood plasma.
Blood group B
You have B antigens on the surface of your red blood cells and A antibodies in your blood plasma.

56. Blood Groups
Blood group AB You have both A and B antigens on the surface of your red blood cells and no A or B antibodies at all in your blood plasma.
Blood group 0
You have neither A or B antigens on the surface of your red blood cells but you have both A and B antibodies in your blood plasma.

57. Genetic Disorders

58. AMNIOCENTESIS
A technique used to determine the genetic traits of a baby before it is born

62. Klinefelter Syndrome
Have male genitalia and internal ducts, but underdeveloped testes
Do not produce sperm
Slight enlargement of the breasts
47,XXY
1 out of every 500 male births

63. Turner Syndrome Has female external genitalia Underdeveloped ovaries
Short (under 5 feet)
Webbed Neck
Broad, Shield-like chest
45,X
1 out of every 3000 female births

64. Cri-du-Chat Syndrome Partial monosomy (part of 1 chromosome is lost)
Loss of about 1/3 of the short arm of chromosome 5
Anatomical malfomrations (gastrointestinal and cardiac complications)
Mentally retarded
Abnormal development of the larynx which makes the baby’s cry sound like a cat’s cry
1 in 50,000 live births

65. Down Syndrome
BKA trisomy 21 (47, 21+); 3 copies of the 21st chromosome
Short
Small round heads
Protruding, furrowed tongues which cause mouth to remain partially open
Mentally challenged (IQ below 70)
Shortened life expectancy (<50)
Prone to reparatory disease and heart malformations
Have 15x higher chance of getting leukemia
Chance of having a baby with Down syndrome goes up as the mother gets older