Rat Genetics Male Rat Dad Phenotype Black Hair

Rat Genetics

Male Rat (Dad) • Phenotype – Black Hair • Genotype – BB / Bb

Female Rat (Mom) • Phenotype – Gray (shade of Black) Hair Coat • Genotype – BB / Bb

Vocabulary Terms • Heterozygous: The 2 alleles for the trait are different ex. Bb 1 dominate & 1 recessive • Homozygous: The 2 alleles for the trait are the same ex. BB or bb 2 dominant or 2 recessive • Phenotype: Physical appearance • Genotype: Genetic traits (BB /Bb / bb)

What will their offspring’s phenotype and genotype be if female is heterozygous dominant for black hair and the male is homozygous for black hair? • Female Male – Bb -BB • Offspring • • Black Hair White Hair Homozygous Heterozygous

st 1 Mating Offspring / F 1 Generartion (babies) • 9 lived • Phenotype – 100% Black Hair Coat • Genotype – 100% BB / Bb

What will their offspring’s phenotype and genotype be if male and female is heterozygous dominant for black hair? • Female Male – Bb -Bb • Offspring • • • Black Hair White Hair Homozygous Dom. Rec. Heterozygous

2 nd Mating / F 2 Generation Offspring • phenotype – 75% Black Hair Coat – 25% White Hair Coat • Genotype – 75% BB / Bb – 25% bb

So based on the phenotypes of the second mating offspring we now know…. • Both Female (mom) and Male (dad) genotype has to be. . –Bb Heterozygous Dominant for black hair

Your Turn: Name: ______ Per___ What would happen if you breed the white homozygous (bb) rat to an black homozygous rat (BB)? • Phenotype black ____% white ____ % • Genotype • ___ ______% • Draw/Color picture to show Phenotype of offspring on back of this sheet