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Unformatted text preview: Chapter 14 Patterns of Inheritance People Josef Kolreuter 1760- hybridization (different tobacco strains>fertile offspring produced) T.A. Knight 1823- crossed true breeding varieties of pea plants Gregor Mendel Father of Genetics -1822- 1894 R.C. Punnett Gregor Mendel book Versuche ber Pflanzen-Hybride (Treatises on Plant Hybrids) 1865 Worked with garden peas Established principles of heredity Terms Gene- heredity Allele- Any of the alternative versions of a gene that produce distinguishable phenotypic effects. Dominant- An allele that is fully expressed in the phenotype of a heterozygote Recessive- An allele whose phenotypic effect is not observed in a heterozygote Homozygous (pure, true breeding)- Having two identical alleles for a given gene (PP)=D (pp)=R Heterozygous (hybrid)- Having two different alleles for a given genes(Pp)=D Self fertilization- Fertilization by sperm from the same animal, as in some hermaphrodites, or by pollen from the same flower. Cross fertilization- fertilization in which the gametes are produced by separate individuals or sometimes by individuals of different kinds Perfect flower- A flower that contains both male and female parts. It can pollinate itself and does not needwind, insects or other means to transfer it's pollen. The pollen is produced in the same flower that produces the seed. Monohybrid- organism that is heterozygous with respect to a single gene of interest. All the offspring from a cross between parents homozygous for different alleles are monohybrids. Ex: parents of genotypes AA and aa produce a monohybrid of genotype Aa. Dihybrid- An organism that is heterozygous with respect to two genes of interest. All the offspring from a cross between parents doubly homozygous for different alleles are dihybrids. For example, parents of genotypes AABB and aabb produce a dihybrid of genotype AaBb. Parent cross- 1 st cross F1 First filial- The first filial, or hybrid, offspring in a series of genetic crosses. F2 Second filial- Offspring resulting from interbreeding of the hybrid F1 generation Phenotype- appearance or observable traits. which are determined by its genetic makeup Genotype- The genetic makeup, or set of alleles, of an organism Punnett square- diagram used in the study of inheritance to show the predicted results of random fertilization in genetic crosses Testcross- Breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype. The ratio of phenotypes in the offspring reveals the unknown genotype Backcross- the cross of an F 1 hybrid to one of the homozygous parents; for pea plant height the cross would be Dd x DD or Dd x dd; most often, though a backcross is a cross to a fully recessive parent Why use peas? Easy to cultivate, small in size, reproduce quickly, large amount of offspring, self-fertilize, cross- fertilize, many different varieties...
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