This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: By the end of chap. 2 you should be able to: •Define important genetic terms •Distinguish between P, F1and F2generations •Describe Mendel’s laws •Predict the outcomes of genetic crosses •Calculate and evaluate the role of chance in •Selected 7 characteristics that had only 2 options—makes things simple! Early 1900s-basic principles of genetics developed Gregor Mendel-studied pea plants (grow quickly, 1 generation=1 growing season, lots of offspring, many varieties, genetically pure) Selected 7 characteristics with only 2 options Genetics Terminology Alleles: alternative forms of a gene Gene: a genetic factor that helps determine a trait Cross: a mating between 2 individuals Genotype: the genetic constitution of an organism Homozygote: Both alleles at gene locus are the same Heterozygote: Both alleles are different at gene locus Locus(loci): specific place on chromosome where gene is located Phenotype: physical manifestation of a genetic trait Different alleles occupy same locus on homologous chr Basic genetic terminology/abbreviations Crosses depicted with symbols that represent each allele Uppercase = dominant allele Lowercase = recessive allele Each allele can be represented by 1, 2, or 3 letters The common allele found most often in the wild is called the wild-type allele— designated by + Example: recessive allele for yellow eyes in Oriental fruit fly = ye Wild-type allele = ye+ Can use a slash to separate the alleles ye+/ye A given phenotype arises from a genotype that develops within a specific environment Phenotype = interaction between the genotype and environment Genotype determines the potential for development—sets a limit, but how the phenotype develops depends on effects of other genes and environment Balance between genotype and environment varies Seed shape—differences in phenotype due mainly to genotype Tree height—differences in phenotype due mainly to environmental factors (water, light) Genotype is inherited, not the phenotype !!!...
View Full Document
- Fall '07
- Genetics, recessive allele