Presentation on theme: "Chapter 11 – Observable Patterns of Inheritance. 11.1 Mendel’s Insight into Inheritance Patterns Monk in Austria -experimented with pea plants to see."— Presentation transcript:
Chapter 11 – Observable Patterns of Inheritance
11.1 Mendel’s Insight into Inheritance Patterns Monk in Austria -experimented with pea plants to see how genes are passed on to generation. -found that sperm and egg cells contain genetic information that play a part in the genes of the offspring. Gregor Mendel “Father of Genetics”
Terms to Know: Gene locus – location of a specific gene Allele – variations of a gene
Genes Units of information about specific traits. When identical alleles are passed on generation after generation this is called a true-breeding lineage. When offspring inherit a pair of non-identical alleles for a trait this is called a hybrid offspring.
Homozygous -when both alleles are identical (TT) Heterozygous -when alleles are not identical (Tt)
Genotype and Phenotype Genotype – genetic makeup of an individual. Phenotype – physical appearance of an individual. Observable traits.
Tracking Inheritance P = parental generation F1 = first-generation offspring F2 = second-generation offspring
11.2 Mendel’s Theory of Segregation Mendel tested the idea that a plant inherits two units (genes) of information about a trait. He performed a Monohybrid Cross -cross of two parents that are homozygous for different versions of a single trait. F1 offspring will be hybrid, heterozygous.
Tall P Dwarfx F1 All Tall Phenotype Monohybrid Cross Clearly Tall is Inherited… What happened to Dwarf? F1 x F1 = F2 F2 3 / 4 Tall 3:1 ratio 1 / 4 Dwarf Dwarf is not missing…just masked as “recessive” in a diploid state… Tall is dominant to tall. DDdd Dd Genotype Homozygous Dominant Homozygous Recessive Heterozygous Dwarf dd Tall Dd d Tall Dd Tall DD D dD Punnett Square: possible gametes
Probability The chance that an event will occur.
Punnett-square Method If half of a plant’s sperm or eggs were a and half were A, then four outcomes would be possible each time a sperm fertilized an egg. Not precise Possible eventProbable outcome Sperm A meets egg A¼ AA offspring Sperm A meets egg a¼ Aa Sperm a meets egg A¼ Aa Sperm a meets egg a¼ aa
Testcrosses Fertilizing different genotype plants to see results. Test results may reveal whether the organism is homozygous dominant or heterozygous.
Segregation Diploid cells have pairs of genes, on pairs of homologous chromosomes. The two genes of each pair are separated from each other during meiosis, so they end up in different gametes. They do not effect eachother.
11.3 Independent Assortment Dihybrid Crosses – crossing two traits. Mendel crosses pea plants with two pairs of genes that were homozygous. 9:3:3:1 ratio