Biology I Chapter 9

1. Biology I Chapter 9 Fundamentals of Genetics

2. List 5 characteristics that can be passed on in families. Do Now

3. Review Gene A segment of DNA that is located in a chromosome and that codes for a specific hereditary trait. Crossing Over Occurs during Prophase I of Meiosis and allows for the exchange of genetic material between homologous chromosomes and results in genetic variation.

5. Gregor Mendel “Father of Genetics”

6. Heredity Heredity-the passing of traits from parents to offspring Characteristic-a heritable feature. Ex. Flower color Trait-genetically determined variant of a characteristic Ex. Purple or White

7. Plant Review Anther-male reproductive part Stigma-female reproductive part Pollination-occurs when pollen grains produced in the male reproductive parts of a flower are transferred to the female reproductive parts. Self-pollination-occurs when pollen is transferred from the anthers of a flower to the stigma of that flower or to a flower on the same plant. Cross-pollination-occurs between flowers of two plants.

8. True Breeding True-breeding-(Pure)-always produces offspring with that trait when they self-pollinate.

9. Do Now • List three traits that can be passed on in families.

10. Generations P generation-the first two individuals that mate in a genetic cross. F1 generation-the result of crosses between individuals of the parental generation. F2 generation-two members of the F1 generation are allowed to breed with each other.

11. Gene Types Dominant-A genetic trait that appears in every generation of offspring Recessive-A trait that is not expressed in the F1 generation resulting from the crossbreeding of two genetically different, true-breeding organisms.

12. Law of Segregation Law of Segregation-alleles of a gene separate from each other during meiosis. To describe how traits can disappear and reappear in a certain pattern from generation to generation.

13. Law of Independent Assortment Law of Independent Assortment-the inheritance of one trait had no effect on the inheritance of another

14. Molecular Genetics Molecular Genetics-the study of the structure and function of chromosomes and genes. Chromosome-threadlike structure made up of DNA. Gene-the segment of DNA on a chromosome that controls a particular hereditary trait.

15. Molecular Genetics Allele-each of two or more alternative forms of a gene. Letters are used to represent alleles. Capital letters refer to dominant alleles. Lowercase letters refer to recessive alleles.

16. Genetic Crosses Genotype-refers to the set of alleles it has inherited. Phenotype-reflects all the traits that are actually expressed; the organism’s appearance.

17. An organism's genotype describes its specific combination of alleles. For example, an Aa genotype is heterozygous for the A allele. An organism's phenotype describes a visible trait, such as tall height, brown eyes, or black fur. How does genotypic variation occur? A. Genotypic variation only occurs during binary fission. B. Genotypic variation occurs when alleles are randomly sorted during asexual reproduction. C. Genotypic variation only occurs when genetic mutations occur. • Genotypic variation occurs when alleles are randomly sorted during sexual reproduction. Answer: D Do Now

18. Genetic Crosses Homozygous-Both alleles of a pair are alike. Homozygous dominant BB Homozygous recessive bb Heterozygous-two alleles in the pair are different. Bb

19. Probability Probability-the likelihood that a specific event will occur. Number of times an event is expected to happen Probability= Number of times an event could happen

20. During an experiment, the dominant trait of brown eyes appeared 6 times, and the recessive trait of blue eyes appeared 2 times. Using the probability equation, what is the probability that the dominant trait will appear in a similar cross? Do Now

21. Monohybrid Cross Monohybrid Cross-a cross in which only one characteristic is traced Punnett Square-predicts the probable distribution of inherited traits

22. Example 1: Homozygous x Homozygous dominant recessive

23. Example 2: Homozygous dominant x Heterozygous

24. Example 3: Heterozygous x Heterozygous Phenotypic Ratio-the ratio of the phenotypes; the organism’s appearance. 3 Black: 1 Brown Genotypic ratio-the ratio of the genotypes 1 BB: 2 Bb: 1 bb

25. Example 4: Testcross Testcross-an individual of unknown genotype is crossed with a homozygous recessive individual. Can determine the genotype of any individual whose phenotype expresses the dominant trait.

26. Example 5: Incomplete Dominance Complete Dominance-one allele was completely dominant over another Heterozygous plants and homozygous dominant plants are indistinguishable in phenotype. Incomplete Dominance-occurs when the phenotype of a heterozygote is intermediate between the phenotypes determined by the dominant and recessive traits.

27. Incomplete Dominance • Heterozygous x Heterozygous

28. Example 6: Codominance Codominance-occurs when both alleles for a gene are expressed in a heterozygous offspring.

29. Crash Course-Heridity

30. Dihybrid Cross Dihybrid Cross-a cross in which two characteristics are tracked.

31. Example 1 Homozygous x Homozygous dominant recessive

32. Example 2 Heterozygous x Heterozygous 9:3:3:1

33. Do Now

34. What is the genotype in box 1? Homozygous for freckles What is the genotype of box 2? Heterozygous What is the genotype of box 3? Heterozygous What is the genotype of box 4? Homozygous for no freckles

35. In rabbits, black fur (B) is dominant over brown fur (b). Cross Bb x Bb

36. What is the expected genotypic ratio resulting from a homozygous dominant x heterozygous monohybrid cross?