1. Study of the Inheritance of Traits Chapter 10-11 Textbook
Heredity and Genetics
Study of the Inheritance of Traits Chapter Textbook

2. Objectives
Explain Mendel’s laws of segregation and independent assortment, and their role in inheritance
Demonstrate results of sexual reproduction with dominant/recessive traits, incomplete dominance, codominance, and sex-linked traits like hemophilia and color-blindness.

3. Objectives
Prepare a position about intentional gene modification, mutation.
Defend and support your position in either a powerpoint or a paper.
Analyze bioethics and science in public policy and law.

4. What are Genes?
Genes control the looks of mice, flies, people, and all other living things.

5. Chromosomes Contain Genes
Genes are codes for proteins, which give us our body traits
Genes, found on chromosomes, have 1 to 8 alleles per trait
An Allele is 1 copy of a gene on each of the two chromatids of a chromosome
allele
Gene

6. Genes and alleles ...

7. How Were Genes Discovered?

8. Gregor Mendel ( )
Mendel was the gardener in a Monastery in Brno, Czech Republic in 1850’s
Discovered principles of genetics by experimenting with 900 pea plant crosses

9. Mendel’s experiment
Mendel cut off pollen producers (anthers) of flower to prevent self-pollination of peas
He then pollinated this plant with a plant having a different trait.
He tallied the results of the crosses.

10. Mendel’s experiment…
He cross-pollinated pea plants of different characteristics
Height of plant
Pea pod color
Pea pod texture
Flower position

11. Mendel’s first principle
Segregation

12. P Generation (parent)
Mendel crossed a Tall pea plant with a short pea plant
Mix of two breeds is called a hybrid

13. F1 Generation (1st offspring)
Mendel found that the offspring were all Tall plants
Trait for Tallness showed up in all 1st generation offspring
The short trait disappeared.

14. Terms… The trait that shows up is called Dominant
The trait masked or hidden by the dominant allele is called recessive

15. Phenotype Traits or looks are called phenotype
The phenotype could be tall, short, etc.

16. The genotype We represent genotype by two letters
One represents the mother’s gene
The other represents the father’s gene.
TT genotype plant would be tall phenotype
tt genotype plant would be short phenotype
Tt genotype plant would be tall phenotype

17. Terms TT is called homozygous dominant genotype
Homozygous recessive genotype: tt
Tt is called heterozygous dominant genotype

18. Mendel then crossed the Hybrid Tall F1 plants
3/4 offspring were Tall and 1/4 offspring were short.
The recessive trait had reappeared in the 2nd generation

19. Segregation
In a hybrid cross, the recessive trait disappears in the F1 generation then reappears in F2 generation.
If you cross a purebred Tall plant with a purebred short plant, the 1st generation will all be Tall.
If you cross the 1st generation plants their offspring will be ¾ Tall and ¼ short.

20. 1st Conclusion of Mendel
male pollen
Genes control traits from parent to offspring
Offspring inherit one set of genes from each parent.
Organisms have two sets of alleles per gene for each trait.
female ovule
New seed

21. 2nd principle of Mendel
How are traits passed to offspring?

22. Independent Assortment
The two chromsomes carrying the genes/alleles are Independently separated during anaphase of meiosis
The genes for different traits (hair color, eye color, etc) may be passed to offspring independently of the other traits.

23. Mendel’s Conclusions Offspring inherit one gene from each parent.
Genes control traits from parent to offspring.
Two or more genes can produce a trait in a person
One gene could be Dominant and mask the other recessive gene making the offspring show the dominant trait
Both genes could be dominant and the offspring could have the dominant trait
Both genes could be recessive and the offspring will have the recessive trait.

24. Punnett Square

25. Building a Two Trait Punnett SquareBb
Assemble a 4 square punnet square to see which alleles will pair for each parent. T t B BT Bt b bT bt

26. Two trait (Dihybrid cross)
Take the allele combinations for each parent and place them on the side of a 16 square Punnet Square BT Bt bT bt

27. Two trait (Dihybrid cross)
There will be four letters in each box
Usually we put the Capital or Dominant first
Offspring will have a 9:3:3:1 ratio BT Bt bT bt
BBTT
BBTt
BbTT
BbTt
BBtt
Bbtt
bbTT
bbTt
bbtt

28. Video on Mendel’s laws and Punnet Squares
Mendel
Punnet

29. Incomplete Dominance Two alleles are neither dominant nor recessive
A red rose crossed with a white rose can produce a pink rose. Neither white nor red is dominant so they both mix.

30. Codominance Both alleles are dominant
A red horse or cow and a white horse or cow produce a roan horse or cow with red and white hairs

31. Codominance
A white chicken and a black chicken crossed can produce a black & white striped chicken
Both white and black show up

32. Punnett Square with Codominance
Each allele is dominant so each offspring will inherit the trait from the father and mother. Both show up in offspring

33. Codominance in Horses and Cows
Red and White produce a Roan. Both traits are produced in offspring

34. Codominance in chickens and flowers

35. Sex-linked Traits Males have an X chromosome and a y chromosome (Xy)
All pairs match up but one pair
Females have two X chromosomes (XX)
All pairs match up
Traits can be masked in females by another dominant allele
Traits in males on the X chromosome are alone. The y chromosome carries different information.

36. Color blindness

37. Sex-linked traits
Eye color in Fruit Flies

38. Hemophilia (blood clotting problems)
Video:
Queen Victoria’s son

39. Further information