SECTION 11 2 Genetic Crosses I Genotype and

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: TT, Tt Short: tt 2. Phenotype: physical characteristics shown because of genotype a. EX: Tall or short 3. Homozygous: alleles that are the same for a characteristic a. EX: Tall: TT Short: tt 4. Heterozygous: alleles that are different for the same characteristic a. EX: Tall: Tt

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 Probability of Short Peas: 25% = 50/200

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 ______ vs. _______ Ex: Flower Color Dominant: Purple: AA, Aa Recessive: White: aa Genotype: Phenotype:

b. Homozygous vs. Heterozygous ____ vs. _______ Ex: Flower Color Dominant: Purple: AA, Aa Recessive: White: aa Genotype: Phenotype:

c. Heterozygous vs Heterozygous _____ vs. _______ Ex: Flower Color Dominant: Blue: BB, Bb Recessive: White: bb 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 ____ x ______ Ex: Flower Color Flower Height Dominant: Purple: AA, Aa Recessive: White: aa Dominant: Tall: TT, Tt Recessive: Short: tt

b. Heterozygous x Heterozygous Ex: Flower Color Flower Height Dominant: Blue Recessive: White Dominant: Tall Recessive: Short

V. Patterns of Inheritance 1. Complete Dominance: Dominant trait completely masks recessive trait 2. Incomplete Dominance: Heterozygote has phenotype intermediate btwn phenotypes of two homozygotes - Possible to mix a red and white flower to make pink

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

VI. 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 )

Multiple Alleles Blood Type: Dominant: Recessive: Type A: IAIA, IA i Type B: IBIB, IB i Type AB: IAIB Type O: ii Genotype: Phenotype:

VIII. Sex Chromosomes • Sex Determination: –Example: Male: XY Female: XX –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 recessive) Genotype: Phenotype:

X. Pedigree Charts

1. Autosomal Dominant

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