GENETICS Chapter 9 SECRET LIFE OF A DOG

GENETICS Chapter 9

SECRET LIFE OF A DOG • https: //vimeo. com/26671405 • 37: 00 – 46: 37 • People have selected and mated dogs with preferred traits for more than 15, 000 years. • Over thousands of years, such genetic tinkering has led to the incredible variety of body types and behaviors in dogs today. • Considered societies longest running genetic experiment

FATHER OF GENETICS – MENDEL Figure 9. 4

Removed stamens from purple flower. Parents (P) Carpel Stamens Transferred pollen from stamens of white flower to carpel of purple flower. Pollinated carpel matured into pod. Planted seeds from pod. Offspring (F 1)

P Generation (purebred parents) Purple flowers White flowers F 1 Generation All plants have purple flowers Fertilization among F 1 plants (F 1 × F 1) F 2 Generation 3 4 of plants have purple flowers 1 4 of plants have white flowers

• A gene locus is a specific location of a gene along a chromosome. • Alleles (alternative versions) of a gene reside at the same locus on homologous chromosomes. • However, the two chromosomes may bear either identical alleles or different ones at any one locus. Gene loci Homologous chromosomes Genotype: Dominant allele P a B P a b PP aa Bb Homozygous for the dominant allele Homozygous for the recessive allele Recessive allele Heterozygous with one dominant and one recessive allele

SAMPLE PROBLEMS • A coin is flipped 5 times and comes up heads each time – what is the probability of getting heads a 6 th time? • ½ - there are only two possible outcomes and they are equally likely

SAMPLE PROBLEMS • Are the following heterozygous or homozygous? • RR, Rr, yy, Yy. RR

SAMPLE PROBLEMS • What is the phenotype of the following • Yy, Rr, yy, Yy. Rr • Assume Y is the dominant allele for yellow seeds (vs. green) and R is the dominant allele for round seeds (vs. wrinkled)

SAMPLE PROBLEMS • What is the probability of Rr x Rr producing wrinkled seeds? • Assume R is the dominant allele for round seeds (vs. wrinkled)

SAMPLE PROBLEMS • What is the probability of Yy x yy producing green seeds? • Assume Y is the dominant allele for yellow seeds (vs. green)

SAMPLE PROBLEMS • What is the probability of Rr. Yy x RRYy producing Rr. Yy? • Rule of multiplication • states that the probability of a compound event is the product of the separate probabilities of the independent events

TYPES OF DOMINANCE (OTHER THAN COMPLETE) Incomplete Dominance Co-Dominance