Math 101 Project 3 - Inheritance and the Principle of Dominance
This project involves reading about the theory of inheritance, researching some genetic traits, and calculating the probability of inheriting certain traits of your choosing.
General Comments
For this project you are expected to turn in a short paper answering all of the questions below, describing
any calculations you made and their outcomes, and summarizing the results of the project. The questions
being addressed must be properly posed in the paper along with their answers. Supporting data and
graphs must also accompany the paper, and any Excel sheets used for calculating should be submitted at
the same time.
Citations must be given for any and all outside sources used. There is a citation guide on e-reserves that
will provide information on the proper way to cite all sources.
You may discuss the project with other students in the class but the work must be your own (and written
up separately). In particular, you should have different questions, data, and assumptions. Plagiarism is a
serious academic offense and will result in a zero on the paper.
Email me with questions about the project. You should also feel free to come discuss any piece of it at
any point. I am happy to look at calculations and drafts.
This project is due Wednesday, May 9th by midnight.
Part 1
Read through the Hardin - “Inheritance, Probability” in the Project 3 folder on e-reserves. Briefly explain
the history of genetics, what Mendel did, and how probability is used. Additionally, describe what is
meant by “The Theory of Inheritance” and what the“Principle of Dominance” is. Make sure to include
some of the relevant definitions such as phenotype and genotype, dominant and recessive alleles, heterozygous and homozygous, and Punnett square. There are a couple of other sources of interest are in the same
folder should you want/need more information of different descriptions.
Part 2
Mendel’s famous experiments involved inheritance in pea plants. One of the traits he observed was the
color of the seeds. Yellow seeds are the dominant trait and green seeds the recessive trait, genotypes AA
and Aa result in yellow phenotype and only aa results in green phenotype.
If one plant of genotype Aa produces 4 seeds, how many would you expect to be yellow and how many
green? If each of those seeds is planted and each later produces 4 seeds, how many of the 16 new seeds
would you expect to be yellow and how many green? What would happen in the third generation? (Some of
the handouts will help with this - Mendel’s paper section 7 or anthro.palomar.edu/mendel/mendel 2.htm
- you can also come ask me about this.)
Part 3
Look up two genetic traits (for example hair line, dimples, colorblindness, etc.). They can be simple
dominant/recessive traits as in the pea pod experiment, or they could be codominant (blood type) or
intermediate expression (there is a middle option between the dominant AA and recessive aa resulting
phenotypes, for example a flower for which AA is red, aa is white, and Aa is pink). Explain each of the
two traits and how they are passed on genetically.
Assume a genotype for each of the traits (for person A), and then pick two other genotypes (for person B
and C). Assume person A has a child with person B. What are the chances that they will inherit each of
the traits? Now assume the child from the first pair has a child with person C. What are the chances that
they will inherit each of the traits? Comment on how traits pass down two generations, and the likelihood
of the grandchild having each of the traits.