1. Genetics 101

2. Gregor Mendel ( )
First scientist to apply mathematics to experimentation.
Suggested a hypothesis to explain inheritance.
His main goal was to find a pattern of inheritance based on observations.
Observed patterns of inheritance using pea plants.
While Mendel's research was with plants, the basic underlying principles of heredity that he discovered also apply to people and other animals because the mechanisms of heredity are essentially the same for all complex life forms.
Mendel chose garden peas (pisum sativum) for genetic experiments.
Why is this significant?

3. Mendel and the Pea Plant

4. Common Garden Pea

5. Round vs. Wrinkled Pea Seeds

7. But, where the heck did Shorty go????
Parental
Generation (P)
First Filial
Generation (F1)
But, where the heck did Shorty go????

8. Where the heck did Shorty come from???
2nd Filial
generation
(F2)

9. Mendel called them tall and short “factors”, we now call them “alleles
Alleles are
alternate forms
of a trait.
What two alleles are shown here?
Can you
identify
the
generations?

10. The pair of alleles for any trait comprise the gene for that trait.

11. Dominant Recessive Trait shown Trait masked, hidden -tt- short
-TT- Tall
-Tt – tall
Trait masked, hidden
-tt- short
* recessive only show s when homozygous

12. Punnett Square P P P p p p P p

13. Punnett Square T t TT Tt Tt tt T t Genotype- TT- 1 Tt- 2 tt- 1
Mendel’s F2 Generation
T- tall (dominant)
t – short (recessive)
Cross - Tt x Tt
Punnett Square
T t
Genotype-
TT- 1
Tt- 2
tt- 1
Phenotype
Tall- 3
Short-1 T t TT Tt Tt tt

14. MA- ___________ CA-_________
Bell Ringer # 1
1. The trait that is expressed is known as the ___________ trait.
A. recessive
B. dominant
C. hybrid
D. heterozygous
R-EOC- Genetics
MA- ___________ CA-_________

15. MA- ___________ CA-_________
Bell Ringer #
1. A human baby boy inherits a recessive allele from his mother. In which circumstance would he most likely show the trait coded for by the recessive allele?
A. The baby inherits the dominant allele from his father.
B. The allele is on an autosomal chromosome and the baby is a twin.
C. The allele is on the X chromosome.
D. The allele is on the Y chromosome.
R-EOC- Genetics
MA- ___________ CA-_________

16. Mendel’s Experimental Results

17. Punnett Square Analysis
Homozygous dominant (purebred dominant)
Heterozygous (hybrid) R RR Rr r
Homozygous recessive (purebred recessive) Rr rr
Heterozygous (hybrid)

18. What’s the
phenotypic ratio of
round to wrinkled
peas in this pod?
Can you make a
prediction about
the parents?

19. Flower Color

20. Test Cross P p Pp
Used by Mendel to determine unknown genotype of a dominant phenotype.
How can we tell if a purpe flower plant is heterozgous (Pp) or homozygous dominant (PP)? P p Pp pp

21. Intro To Genetics

22. Heredity

23. Vocabulary
Genetics- is the science of genes, heredity, and variation in living organisms.
Allele-is one of two or more forms of a gene .

24. Identical factors- Homozygous -TT,tt Different Factors – Heterozygous
Genetic Terms
Identical factors-
-TT,tt
Different Factors –
Tt (hybrid)
Homozygous
Heterozygous

25. Genotype Phenotype
Genes (TT,Tt,tt) Appearance (ex: blue)

26. A. The environment affects these characteristics after birth.
1. Robert and Susan are married and have two children, one son and one daughter. The children have different hair color and eye color. Which of the following statements explains these differences in the children?
A. The environment affects these characteristics after birth.
B. There is a lack of variation in the genes of parent sex cells.
C. Sexual reproduction produces a fertilized egg that has a unique genetic makeup.
D. Hormone changes in a pregnant woman’s body cause traits to develop differently in a fertilized egg.
R-EOC- Genetics
MA-_______ CA- ______

27. If red is dominant and white is recessive, where do pink carnations come from??????

28. Incomplete Dominance Genotype 1 RR 2 Rr 1 rr
What’s going on here? R r Rr
Genotype
1 RR 2 Rr 1 rr
Phenotype
1 Red 2 Pink 1 White
What are the genotypes and phenotypes shown?? R r RR Rr rr
Incomplete Dominance

29. Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype.
Mixture of traits….

31. Both traits are visible….
Codominance - is a situation in which both alleles are equally strong and both alleles are visible in the hybrid genotype.
Both traits are visible….

32. Co-dominance in Chickens

33. ERMINETTE CHICKENS
These chickens have feathers that are both white and black, but not grey.
BB = black feathers
BW = black and white feathers
WW = white feathers

35. Codominance in blood types
Universal Recipient
Universal Donor

37. Polygenic traits - Multiple alleles
A polygenic trait is one whose phenotype is influenced by more than one gene.
Traits that display a continuous distribution, such as height or skin & eye color, are polygenic.

38. Mendel’s First Law: The Law of Segregation
Alleles do not normally enter the same gamete, they are separated from each other during cell division.
Germ cell Rr
Gametes R r
Can you relate this to meiosis?

39. Mendel’s Second Law: The Law of Independent Assortment
In a dihybrid cross, the segregation of one pair of alleles does not affect the segregation of the second pair of alleles.

42. MA- _________ CA-_______
1. For the trait being followed in the pedigree, individuals II-1 and II-4 in Figure 12-1 can be classified as _____. SC.F.2.4.1
A) homozygous dominant
B) homozygous recessive
C) mutants
D) carriers
R-EOC- ___________
MA- _________ CA-_______

43. MA- _________ CA-_______
In this pedigree, which family members are carriers of Tay-Sachs?
both parents
second and fourth offspring
first and second offspring
mother only
R-EOC- ___________
MA- _________ CA-_______

44. …to be continued…