SECTION 11.2 Genetic Crosses

I. Genotype and Phenotype 1.Genotype: genetic makeup of an organism a.Alleles that give the organism its traits b.EX: Tall:Short: 2.Phenotype: physical characteristics shown because of genotype a.EX:

I. Genotype and Phenotype 3.Homozygous: alleles that are the same for a characteristic a.EX: Tall: Short: 4.Heterozygous: alleles that are different for the same characteristic a.EX: Tall:

II. Probability 1.Probability: the chance of a specific trait occur or not occurring in an organism 2.Probability= # of times trait is expected to happen # of opportunities for an trait to happen 3.Example: Tall peas: 150 Short peas: 50

III. Monohybrid Crosses 1.Monohybrid: crossing one trait from two different organisms 2.Use a Punnett Square 3.Possible Crosses: a.Homozygous x Homozygous b.Homozygous x Heterozygous c.Heterozygous x Heterozygous

a. Homozygous vs. Homozygous Ex: Flower Color Dominant: Purple Recessive: White Genotype: Phenotype:

b. Homozygous vs. Heterozygous Ex: Flower ColorDominant: Purple Recessive: White Genotype: Phenotype:

c. Heterozygous vs Heterozygous Ex: Flower ColorDominant: Blue Recessive: White Genotype: Phenotype:

IV. Dihybrid Crosses 1.Cross organisms with 2 different traits 2.Possible Crosses a)Homozygous x Homozygous b)Heterozygous x Heterozygous

a. Homozygous x Homozygous Ex: Flower ColorDominant: Purple Recessive: White Flower HeightDominant: Tall Recessive: Short

b. Heterozygous x Heterozygous Ex: Flower ColorDominant: Blue Recessive: White Flower HeightDominant: Tall Recessive: Short

V. Patterns of Inheritance 1. Complete Dominance: Dominant trait completely masks recessive trait

V. Patterns of Inheritance Incomplete Dominance: Heterozygote has phenotype intermediate btwn phenotypes of two homozygotes -

Incomplete Dominance Flower Color: Dominant: Red (R) Recessive: White (r) Intermediate: Pink Genotype: Phenotype:

VI. Codominance Codominance: Phenotype of the heterozygote includes the phenotypes of both homozygotes 1.No one allele is dominant, recessive, or blends 2.Example: animal fur color, blood types

VII. Multiple Alleles Multiple Alleles –More than two allele varieties are present within a group of individuals a)Varies genotype and phenotypes b)Example: Blood Type ( ABO Group )Blood Type

Multiple Alleles Blood Type: Dominant: Type A and B Recessive: Type O Genotype: Phenotype:

VIII. Sex Chromosomes Sex Determination: –Example: –Disorders/Syndromes: Turner Syndrome: 1 X & 0 Y (female) Klinefelter Syndrome: many X & 1-2 Y (male) Poly-X females: 3 X (female)

IX. Sex-Linked Characteristics Determined by genes located on ________________ –Most are ____ -linked –Example: Color Blindness (X-linked)Color Blindness Genotype: Phenotype:

X. Pedigree Charts

1. Autosomal Dominant

2. Autosomal Recessive: Heterozygotes carry the recessive allele but exhibit the wildtype phenotype