SOLUTION MANUAL FOR GENETICS FROM GENES TO GENOMES, 7TH EDITION, MICHAEL GOLDBERG, JANICE FISCHER, LEROY HOOD, LELAND HARTWELL

chapter 1 Mendel’s Principles of Heredity Synopsis Chapter 1 covers the basic principles of inheritance that can be summarized as Mendel’s Laws of Segregation (for one gene) and Independent Assortment (for more than one gene). Key terms genes and alleles of genes – A gene determines a trait, and different alleles or forms of a gene exist. The color gene in peas has two alleles: yellow and green. genotype and phenotype – Genotype is the genetic makeup of an organism (written as alleles of specific genes), while phenotype is how the organism looks. homozygous and heterozygous – When both alleles of a gene are the same, the individual is homozygous for that gene (or pure breeding). If the two alleles are different, the organism is heterozygous (also called a hybrid). dominant and recessive – The dominant allele is the one that controls phenotype in the heterozygous genotype; the recessive allele controls phenotype only in a homozygote. monohybrid or dihybrid cross – a cross between individuals who are both heterozygotes for one gene (monohybrid) or for two genes (dihybrid). testcross – performed to determine if an individual with the dominant characteristic is homozygous or heterozygous: An individual with the dominant phenotype but unknown genotype is crossed with an individual with the recessive phenotype. Key ratios 3:1 – Ratio of progeny phenotypes in a cross between monohybrids [Aa × Aa → 3 A– (dominant phenotype) : 1 aa (recessive phenotype)] 1:2:1 – Ratio of progeny genotypes in a cross between monohybrids (Aa × Aa → 1 AA : 2 Aa : 1aa) 1:1 – Ratio of progeny genotypes in a cross between a heterozygote and a recessive homozygote (Aa × aa → 1 Aa : 1aa) 1:0 – All progeny are the same phenotype. Can result from either of two cases: [AA × – – → A– (all dominant phenotype)] [aa × aa → aa (all recessive phenotype)] 9:3:3:1 – Ratio of progeny phenotypes in a dihybrid cross (Aa Bb × Aa Bb → 9 A– B– : 3 A– bb : 3 aa B – : 1 aa bb) SOLUTION MANUAL FOR GENETICS FROM GENES TO GENOMES, 7TH EDITION, MICHAEL GOLDBERG, JANICE FISCHER, LEROY HOOD, LELAND HARTWELL