Genetics

1. Genetics It all started with Mendel!

2. Genetics It all started with Mendel!

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

5. How does it work? Women carry XX sex chromosomes Men carry XY sex chromosomes (technically, men determine the sex of a baby) Many diseases/conditions are carried on the X chromosome (nothing is carried on the Y) ** ColorBlindness ** Hemophilia Women can be healthy ‘carriers’ Men either have or don’t have the disease.

6. Gregor Mendel An Austrian monk that studied math and science and taught science in a monastery “Father of Genetics” Performed the first scientific study of inheritance on pea plants

7. Pea Plants }form a seed • Use parts of the flowers to reproduce • Pollen = male sex cells • Eggs in flower = female sex cells • Pea plants normally reproduce by self-pollination • Pollen fertilizes flower of the same plant • True-breeding pea plants (“pure bred”)

8. Pea Plants • Pea plants can cross-pollinate • Pollen fertilizes flower of a different plant • 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!

9. Mendel’s 1st experiments • Trait = specific characteristic that varies from one individual to another • Height (tall or short) • Seed color (green or yellow) • Seed texture (smooth or wrinkled) • Mendel crossed plants with contrasting traits • P (Parental) = original pair of plants • F1(First Filial) = first set of offspring (filius means “son” in Latin) • Hybrids = offspring of parents crossed with different traits (aka HETEROzygous)

10. Mendel’s 1st 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

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

12. 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? • 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? • The characteristic only shows up when the dominant allele is not present

13. Mendel’s 2nd experiments • Mendel crossed the F1 hybrid plants • F1(First Filial) = first set of offspring (hybrids) • F2(Second Filial) = offspring of self-pollinated F1 • Dominant vs. Recessive alleles • Upper case letter = dominant allele • Lower case letter = recessive allele

14. Mendel’s 2nd conclusions • The dominant allele masked the corresponding recessive allele in the F1 generation • The reappearance in the F2 generation indicated that the alleles separated during gamete (sex cell) formation • Each gamete contains a single copy of each gene • The recessive alleles can be paired up again in the F2 generation

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

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