Presentation on theme: "MRs Jackie Principles of Genetics Part II. Terminology Allele- alternative form of a gene for a certain trait. Example seed shape R and r, and flower."— Presentation transcript:
Terminology Allele- alternative form of a gene for a certain trait. Example seed shape R and r, and flower color W and w Genotype of the combination of alleles for example RR or Ww or WW. Phenotype- appearance of a trait example being round and wrinkle in plants.
Two traits After Mendel´s first experiment, he studied the inheritance of two traits at once. For example, what types of plants would develop from a cross between a parent plant that produced peas that were round and yellow (RRYY) and a parent that produced peas that were wrinkle (rryy). All will be RrYy round and yellow. Principle of independent assortment Do alleles segregate independently of each other during gamete formation? Or do they stay in the same combination that is RY and ry? Mendel found that alleles segregates independently during gamete formation
Two Trait Cross RY Ry rY ry RRYYRRYyRrYYRrYy RRYyRRyyRrYyRryy RrYYRrYyrrYYrrYy RrYyRryyrrYyrryy RY Ry rY ry 9 are Round and yellow 3are round and albino 3 Are wrinkle and yellow 1 wrinkle and albino
Two trait problem In guinea pigs the gene for rough coat (R) is dominant over the gene for smooth coat (r). The gene for black color (B) is dominant over the gene for albino (b). A heteozygous black smooth coated male is bred to a heterozygous black, rough coated female. Use a punnett square to solve this problem.
Homework Explain how two black mice, when mated can produce offpsring that are white. Apply the law of segregation to explain the kind of gametes produced by an animal that has a genotype Aa. One parent is homozygous for a certain trait, and the other is heterozygous.What fraction of their sffspring would you expect to be heterozygous?