This 17-minute video lesson provides an introduction to heredity and classical genetics. It looks at dominant and recessive traits as well as heterozygous and homozygous genotypes. [Biology playlist: Lesson 14 of 71].
This 25-minute video lesson looks at the Punnett square diagram in the study of genetics. It covers dihybrid crosses, independent assortment, incomplete dominance, codominance and multiple alleles. [Biology playlist: Lesson 15 of 71].
Students reinforce their knowledge that DNA is the genetic material for all living things by modeling it using toothpicks and gumdrops that represent the four biochemicals (adenine, thiamine, guanine, and cytosine) that pair with each other in a specific pattern, making a double helix. They investigate specific DNA sequences that code for certain physical characteristics such as eye and hair color. Student teams trade DNA "strands" and de-code the genetic sequences to determine the physical characteristics (phenotype) displayed by the strands (genotype) from other groups. Students extend their knowledge to learn about DNA fingerprinting and recognizing DNA alterations that may result in genetic disorders.
The principles of genetics with application to the study of biological function at the level of molecules, cells, and multicellular organisms, including humans. Structure and function of genes, chromosomes and genomes. Biological variation resulting from recombination, mutation, and selection. Population genetics. Use of genetic methods to analyze protein function, gene regulation and inherited disease.
Students randomly select jelly beans (or other candy) that represent genes for several human traits such as tongue-rolling ability and eye color. Then, working in pairs (preferably of mixed gender), students randomly choose new pairs of jelly beans from those corresponding to their own genotypes. The new pairs are placed on toothpicks to represent the chromosomes of the couple's offspring. Finally, students compare genotypes and phenotypes of parents and offspring for all the "couples" in the class. In particular, they look to see if there are cases where parents and offspring share the exact same genotype and/or phenotype, and consider how the results would differ if they repeated the simulation using more than four traits.
A study guide for Punnett Squares
