1. Trait Gene Protein Genes and Inheritance Genes contain the information for the production of proteins, which specify traits. Since genes are inherited, traits are also inherited. Chromosome

2. Location of Genes In sexually reproducing organisms, cells have a homologous pair of chromosomes (one from each parent). Chromosomes from a homologous pair have the same genes but can have different alleles. Allele: different form of a gene May be dominant or recessive. Chromosome from sperm (dad) Chromosome from egg (mom) Homologous pair of chromosomes

3. Gregor Mendel: Father of Genetics Genetics: branch of biology dealing with heredity Gregor Mendel (1822-1884) was an Austrian monk who is regarded as the father of genetics. Mendel used pea plants to study the inheritance patterns of many traits.

4. Mendel’s View of Inheritance Parent AParent B Offspring New Idea (Mendel) Inherited traits behave as discrete units Parent AParent B Offspring Old Idea Blending of parental traits

5. Mendel’s Pea Experiments Mendel examined a small number of phenotypic characters or traits in peas. Dominant alleles masked recessive alleles. Seed shape round dominant over wrinkled Seed color yellow dominant over green Pod shape inflated dominant over constricted Pod color green dominant over yellow

6. Using a Punnett Square: Monohybrid Crosses Calculates outcomes of genetic crosses. Important vocabulary: Homozygous dominant Heterozygous Homozygous recessive Each parent provides two gametes for the grid Gametes P p P p Parents Pp X Offspring pp PP Pp

7. Genotype and Phenotype The genotype of an organism refers to its genetic make-up. The phenotype of an organism refers to its observable features or traits. pp (homozygous) White PP (homozygous) Purple Pp (heterozygous) Purple Pp (heterozygous) Purple GenotypePhenotype

8. Results of Mendel’s Experiments Seed shape RoundWrinkled 5474 1850 7324 Round Wrinkled TOTAL 2.96 : 1 Seed color YellowGreen 6022 2001 8023 Yellow Green TOTAL 3.01 : 1 Pod color GreenYellow 428 152 580 Green Yellow TOTAL 2.82 : 1 Flower position AxialTerminal 651 207 858 Axial Terminal TOTAL 3.14 : 1 Pod shape InflatedConstricted 882 299 1181 Inflated Constricted TOTAL 2.95 : 1 Stem length TallDwarf 787 277 1064 Tall Dwarf TOTAL 2.84 : 1

9. Mendel’s Law of Segregation Each pair of alleles is separated into different gametes and into different offspring. Gametes contain only one copy of a gene since they only receive one chromosome from each homologous pair. Gametes (sperm Or egg cells) Homologous pair of chromosomes, each has a copy of the gene on it (A or a)

10. aB Gametes Ab Intermediate Cells Law of Independent Assortment Alleles for different traits are sorted independently of each other. All combinations of alleles are distributed to gametes with equal probability. Genotype: AaBb

11. Polydactylism is a dominant trait Selected Hereditary Traits DominantRecessive Right handednessLeft handedness Hitch-hiker’s thumbNormal thumb Polydactylism (extra digits)Normal digits Pattern baldnessNormal hair Free ear lobesAttached ear lobes Hitch-hiker’s thumb Attached ear lobe Handedness Free ear lobe In this crowd of men, almost all show some degree of pattern baldness, a dominant trait.

12. Dominant Human Tongue Roll The ability to roll the tongue into a U-shape when viewed from the front is controlled by a dominant allele. Recessive Phenotype:Cannot roll tongue Allele: t Phenotype:Can roll tongue Allele: T

13. Punnett Square Practice 1. Brown hair (B) is dominant over lighter hair colors (b). If two heterozygotes for this trait mate, what are the: a. genotype frequencies b. phenotype frequencies of the offspring?

14. Punnett Square Practice 2. Dwarfism (D) is dominant over normal height (d). If a person of normal height and a dwarf who is homozygous dominant mate, what are the chances of having a child that is also a dwarf?

15. Punnett Square Practice 3. Polydactyly, or having extra digits (P) is dominant over having five digits on each limb (p). If a woman with polydactyly mates with a normal male, then: a. What are the possible genotypes of the woman? b. What is the genotype of the male? c. Create two Punnett Squares displaying their possible children.

16. Punnett Square Practice 4. Tallness in pea plants (T) is dominant to shortness (t). Round seeds (R) are dominant to wrinkled seeds (r). Set up a Punnett Square showing the mating results of two plants that are heterozygous for both traits.