1. Genetics and Heredity

2. http://ed.ted.com/lessons/how-mendel-s-pea-plants- helped-us-understand-genetics-hortensia-jimenez-diaz Watch this video before completing your foldable or taking notes.

3. Use slides 4 – 18 to aide you in completing your Genetics Foldable

4. Heredity The study of how traits are passed from parents to offspring.

5. Genes and Alleles A gene is a segment of DNA that codes for a specific trait. Ex. Gene for hair color An allele is an alternative form of a gene Ex. Allele for brown hair

6. Dominant Trait that is always observed; masks the recessive form of a trait. Represented by CAPITAL LETTERS W : Widow’s Peak H : Hitchhikers thumb E : Unattached earlobes

7. Recessive Only observed when TWO recessive alleles are present. Represented by a lower case letter. w : Straight hair line h : Absent hitchhikers thumb e : Attached earlobes

8. Homozygous Same alleles joined together Examples: Homozygous Dominant RR, HH, TT, LL Homozygous Recessive rr, hh, tt, ll

9. Heterozygous Different alleles joined together Examples: Ww, Hh, Ee

10. Genotype Combination of alleles in an organism

11. Phenotype The physical appearance The outward expression of a gene What an organism looks like

12. Interpreting a Genotype G: dominant allele for green pea g: recessive allele for yellow pea GG Gg gg

14. Theory of Heredity Inherited allele for purple P HOMOZYGOUS purple flower PP

15. Theory of Heredity Inherited allele for purple flower (P) Inherited allele for pink flower (p) HETEROZYGOUS purple flower (Pp)

16. Theory of Heredity Inherited for pink flower (p) HOMOZYGOUS pink flower (pp)

17. G = Gray fur, g= White fur Subject A Subject B Subject C Genotype for Fur Color GGGggg Phenotype for Fur Color

18. What does homo- mean? ______________ What does hetero- mean? ______________ What does –zygous mean? ________________________ Define homozygous: _______________________________________________ Define heterozygous: _______________________________________________ Circle the following genotype(s) that are homozygous: GGGg gg Circle the following genotype(s) that are heterozygous: GGGg gg same different joined together Homozygous means the same alleles have joined together Heterozygous means different alleles have joined together

19. Now, read through slides 20 – 27. On the back of your “Monohybrid Punnett Squares” Notes summarize Mendel’s conclusions and define: - Law of Segregation - Law of Independent Assortment

20. Gregor Mendel Studied patterns of heredity (passing on of characteristics from parent to offspring) Used the common garden pea in experiments

21. Why did Mendel use peas? Sexually reproducing: able to isolate both male and female gametes Easy to identify traits (characteristics that are inherited) Short life cycle: able to be grown quickly

22. Mendel’s Experiment PARENT GENERATION (P 1 ) Tall true breed x short true breed FILIAL GENERATION (F 1 ) All tall hybrids FILIAL GENERATION (F 2 ) 75% tall hybrids, 25% short hybrids

23. What did Mendel observe? When a true-breeding tall plant is crossed with a true-breeding short plant in the P generation, the F 1 height trait is always predictable. 100% are tall plants. P generation F 1 F 2

24. What happens when the F 1 tall plants are crossed together? Mendel observed that the F 2 generation, the offspring of F 1 plants, are always in a fixed ratio of 3:1 tall:short. Why? P generation F 1 F 2

25. Mendel’s Conclusions There must be two variations for every trait, where each variation is called an allele. Each offspring inherits only one allele from each parent. The alleles are either dominant or recessive. To show the recessive trait, two recessive alleles must be inherited.

26. Mendel’s Conclusions - Law of Segregation Mendel concluded only one allele is passed from parent to offspring for each trait. F1 plants must be heterozygous because the P generation only passed on one tall allele and one short allele. The F1 plant will then pass on to its offspring either a tall or a short allele, never both.

27. Mendel’s Conclusions - Law of Independent Assortment Because organisms are made up of more than one trait, Mendel concluded that the inheritance of one trait does not influence the inheritance of a second trait. Example: Height of the pea plant does not influence the color of the peas Height is independently assorted from color.