1. Do Now What is an inheritance? Something passed from one generation to the next. Something passed from one generation to the next. How is it determined? Your genes from your parents! Your genes from your parents! What are some things you inherited?

2. Genetics-Objectives Describe the principle of dominance Describe what happens during segregation Apply the work of Mendel to the concepts of genes, dominance, and segregation

3. Review: Types of Reproduction Sexual reproduction: two organisms produce a new unique organism = VARIABLITY!!! Asexual reproduction: one organism produces a new nearly identical organism = no variability!

4. Sexual Reproduction Since the hereditary material comes from two parents it resembles both parents in some ways, but is also different from both in others. It has all the characteristics of its species, but at the same time has its own individual characteristics that distinguish it from all other members of that species.

5. The branch of biology that is concerned with the ways in which hereditary information is transmitted from parents to offspring.The branch of biology that is concerned with the ways in which hereditary information is transmitted from parents to offspring. Genetics

6. Gregor Mendel An Austrian monk and father of genetics Performed experiments as he maintained the monastery garden Performed the first scientific study of inheritance on pea plants (1850s-1860s)

7. Why Pea Plants??? 1. Traits are in 2 very different forms Flowers purple or white Flowers purple or white seeds yellow or green seeds yellow or green shape round or wrinkled shape round or wrinkled

8. 2. Male and female reproductive parts are contained in the same flower, you can control mating 3. It is small and grows easily and quickly producing many offspring

9. Pea Plants Use parts of the flowers to reproduce Pollen = male sex cells Pollen = male sex cells Eggs in flower = female sex cells Eggs in flower = female sex cells Pea plants normally reproduce by self-pollination Pollen fertilizes flower of the same plant Pollen fertilizes flower of the same plant True-breeding pea plants (“pure bred”) True-breeding pea plants (“pure bred”) Would the new plants be identical or different than the parent? Why? } form a seed

10. Pea Plants Pea plants can cross-pollinate Pollen fertilizes flower of a different plant Pollen fertilizes flower of a different plant New plants have two parent plants New plants have two parent plants Infer if the new plants would be identical or different from the parents. Why? Mendel cross-pollinated pea plants!

11. Mendel’s 1 st experiments Trait = specific characteristic that varies from one individual to another Height (tall or short) Height (tall or short) Seed color (green or yellow) Seed color (green or yellow) Seed texture (smooth or wrinkled) Seed texture (smooth or wrinkled) Mendel crossed plants with contrasting traits P (Parental) = original pair of plants P (Parental) = original pair of plants F 1 (First Filial) = first set of offspring F 1 (First Filial) = first set of offspring (filius means “son” in Latin) Hybrids = offspring of parents crossed with different traits Hybrids = offspring of parents crossed with different traits

12. Try to predict the results…

13. Mendel’s 1 st results All of the F 1 hybrid offspring had the characteristic of only one of the parents (so it appeared that the characteristic of the other parent had disappeared)

14. Mendel’s 1 st conclusions Biological inheritance is determined by factors passed from one generation to the next = genes Each gene occurred in two contrasting forms that produced different characteristics = alleles

15. The Principle of Dominance Some alleles are dominant and others are recessive

16. Dominant alleles are always expressed. Represent by a capital letter. (B – Dominant for Brown eyes) Represent by a capital letter. (B – Dominant for Brown eyes) Recessive alleles are only expressed if both alleles are recessive. Represented by a lower case letter (b – recessive for blue eyes) Represented by a lower case letter (b – recessive for blue eyes)

17. What happened? If there are at least two alleles for each trait, what happened to the other allele that was inherited? Did the recessive alleles disappear or were they hiding?

18. Dominant vs. Recessive An organism with a dominant allele for a particular trait will always have that form When will a dominant allele show up? When will a dominant allele show up? The characteristic almost always shows up The characteristic almost always shows up An organism with a recessive allele for a particular trait will have that form only when the dominant allele for the trait is not present When will a recessive allele show up? When will a recessive allele show up? The characteristic only shows up when the dominant allele is not present The characteristic only shows up when the dominant allele is not present

19. Mendel’s 2 nd experiments Mendel crossed the F 1 hybrid plants F 1 (First Filial) = first set of offspring (hybrids) F 1 (First Filial) = first set of offspring (hybrids) F 2 (Second Filial) = offspring of self-pollinated F 1 F 2 (Second Filial) = offspring of self-pollinated F 1 Dominant vs. Recessive alleles Upper case letter = dominant allele Upper case letter = dominant allele Lower case letter = recessive allele Lower case letter = recessive allele

20. P Generation F 1 Generation F 2 Generation TallShortTall Short Section 11-1 Principles of Dominance Go to Section: Try to predict the results…

21. Mendel’s 2 nd results The traits controlled by the recessive alleles reappeared! = 25% of F 2 plants There is a new combination of alleles! There is a new combination of alleles! How did the trait disappear and then reappear?

22. Mendel’s 2 nd conclusions The dominant allele masked the corresponding recessive allele in the F 1 generation The dominant allele masked the corresponding recessive allele in the F 1 generation The reappearance in the F 2 generation indicated that the alleles separated during gamete (sex cell) formation The reappearance in the F 2 generation indicated that the alleles separated during gamete (sex cell) formation Each gamete contains a single copy of each gene Each gamete contains a single copy of each gene The recessive alleles can be paired up again in the F 2 generation The recessive alleles can be paired up again in the F 2 generation

23. The Principle of Segregation Alleles are separated (segregated) during gamete (sex cell) formation.

24. The Law of Segregation 1. different version of genes (alleles) account for variations in inherited characters or traits 1. different version of genes (alleles) account for variations in inherited characters or traits Alleles vary in their nucleotide sequences in genes. Ex Blue and Brown eyes, both eye color genes just different versions Alleles vary in their nucleotide sequences in genes. Ex Blue and Brown eyes, both eye color genes just different versions 2. For each trait, organisms inherit 2 alleles, one from each parent. 2. For each trait, organisms inherit 2 alleles, one from each parent. 3. If two alleles differ, then one, the dominant allele, is fully expressed while the other, Recessive, is masked or only partially shown 3. If two alleles differ, then one, the dominant allele, is fully expressed while the other, Recessive, is masked or only partially shown 4. The two alleles for each trait segregate during gamete, sex cell, production. (Meiosis) 4. The two alleles for each trait segregate during gamete, sex cell, production. (Meiosis)

25. concluded that which is called the Gregor Mendel Law of Dominance Law of Segregation Pea plants “Factors” determine traits Some alleles are dominant, and some alleles are recessive Alleles are separated during gamete formation Section 11-3 Concept Map Go to Section: experimented with