Simple Mendelian Genetics: An interactive lecture using "DNA from the Beginning"

This page authored by Jeff Bell, California State University, Chico, based on an original activity by the Dolan DNA Learning Center.
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This material was originally developed through Merlot
as part of its collaboration with the SERC Pedagogic Service.


This active uses a flash based animation, "DNA from the Beginning," to introduce students to the researchers and their experiments that led to the current model for inheritance of genes. Each of the five modules has an animation showing one experiment, a simple multiple choice question based on the experiment, and a more challenging multiple choice question that requires students to extend the concepts further. The modules help students learn about doing genetic crosses, that genes come in pairs, alleles can be dominant or recessive, and how to use Punnet squares to predict ratios of phenotypes in offspring. All five modules can be covered in two to three hours either as an interactive lecture in class or on the students own time.

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Learning Goals

  • Learn the meaning of the terms phenotype, genotype, allele, dominant, recessive, heterozygous, homozygous, hybrid, Punnet square
  • Understand how crosses of plants and animals can be used to investigate the principles of inheritance
  • Use data from crosses to determine which allele is dominant
  • Use data from crosses to determine whether the parents are homozygous or heterozygous
  • Deduce the expected ratios in the progeny given the alleles in the parents

Context for Use

This is a series of linked presentations and questions that is designed to develop a basic understanding of simple Mendelian genetics. It is appropriate for any beginning student in genetics, although previous instruction in cell division, meiosis and sexual reproduction will help students learn this. If the instructor has access to a networked computer and projector in class this can easily be used in place of the traditional lecture over this material. Alternatively, students could be assigned to go through the animations on their own and then submit the answers to the questions.

Description and Teaching Materials

To use this in a lecture, give the students a brief explanation of the topic and warn them that there will be questions along the way. Then go through the first animation, stopping at the end to let the students attempt to answer the first question. They can do this on their own and then vote on the correct answer (using cards, IR clickers, or just a show of hands) or they can work in small groups and then different groups volunteer, or are randomly selected, to explain their answer to the class. All five modules can be done in a couple of hours or, if students are struggling, the instructor can give additional questions and help and take three or four hours to go through all five modules.

The five modules on simple Mendelian genetics are:

Alternatively, the animations could be assigned as homework and class time could be used to discuss the animations and tackle more difficult problems. As the animations reveal whether students have the correct answers to the questions and allow multiple trys, this asingment can't be graded other than as pass (for gettign the answer to all questions) and fail for not doing the assignment.

Teaching Notes and Tips

The animation starts at the very beginning and builds each concept slowly, so students familiar with the Mendel story may be a little bored at the beginning. Slow readers or student unfamiliar with the material may need more time to think about each 'slide,' so the instructor needs to watch the students and try to find an appropriate pace. If the students are working in groups to answer the questions then the instructor has to monitor them carefully to provide the appropriate amount of time.


Student responses in class should indicate whether they are achieving the learning goals.

References and Resources