1. Mendelian Genetics

2. Objectives: After completing this lab topic you should be able to : Explain the different terminologies associated with Mendelian genetics. Should be able to perform monohybrid and dihybrid crosses.

3. A Brief History The science of heredity stems from Gregor Mendel: 1865 Improved upon by Correns, deVries, and vonTschermak: 1900 Continues to be a main branch of scientific study and advancement

4. Study of Genetics is useful Explains evolution which is central dogma of all biology Human behavior Crop improvement Biomedical engineering Insulin Gene therapy

5. Abbreviations P = parents being crossed F 1 = children of the crossed P F 2 = children from F1’s (grandchildren of original P) X = cross

6. Some nifty terminology Monohybrid cross  a mating that tracks the inheritance of ONE trait. Dihybrid = TWO traits being observed DNA--coils--  chromosome…a gene is a particular part of a chromosome, and is thus DNA Homologous chromosomes  similar genes, one from each parent

9. Alleles  alternate versions of the same gene Contributes to genetic variation = GOOD. Homozygous  same allele from mom and dad Ex: AA, aa Heterozygous  different allele from mom and dad Ex: Aa, Bb Hemizygous  sex chromosomes are different Homomorphic (XX female), heteromorphic (XY male)

11. Dominant  allele always appears in phenotype whether homozygous or heterozygous AA or Aa, the A trait is still expressed Recessive  allele only expressed when homozygous Codominance  both alleles are expressed in heterozygotes Blood type (A, B, AB, O)

13. Incomplete dominance  also known as semidominance; heterozygote is intermediate in expression between two different homozygotes Genotype  genetic makeup or allelic constitution of an individual AA, Aa, aa, etc. Phenotype  the expression or appearance of an individual AA and Aa would have the same phenotype, although their genotype if different

14. Red and White are incompletely expressed as Pink

15. Wild type vs. mutant Wild type is “normal” expression of trait Mutant is not normal, or mutated Ratios  proportion of offspring that have a given genotype or phenotype Show modes of inheritance AA, Aa, aa = 1:2:1 genotypic, 3:1 phenotypic

16. Today’s lab will entail the following: Examine the slide of grasshopper testis (demo). Examine the electron micrographs of meiosis. Lab exercise to mimic meiosis using pipe cleaners and beads (handout).