Reflection: Real World Applications Inheritance Patterns (#6 of 6): Pedigrees - Section 2: Anticipatory Set ("Hook")


The study of American genetics (~1900-1940) has revealed a rather checkered record. The entire study of genetics (chiefly using pedigrees) was predicated upon seeking out large families that enabled a more comprehensive analysis of each member and his or her relation to the whole family. In other words, small(er) families were less useful to the geneticist than larger ones. Why is this relevant?

First of all, the typical "large" family in the early 20th century was the ethnic minority and most likely recent immigrants to the States. These bigger families offered a larger sample size with which to draw conclusions about hereditary patterns. Unfortunately the darker side of this inquiry led researchers (erroneously) to conclude certain "genetic disorders" (such as "feeblemindedness") to be present in the largely unwanted immigrant population and then sought to sterilize said individuals under the guise of science and improving the stock of American "gene pool" among other practices. For a compelling read on the topic I suggest reading a 2014 NY Post article chronicling the eugenics movement.

That being said, the challenge for students is to glean information from a given pedigree, however scant, to draw a proper conclusion about the hereditary pattern in question. During the anticipatory set for today's lesson, students were assigned a sample pedigree and using three basic questions, they were to argue in favor of one of three patterns, to the exclusion of the other two. You will see the evidence provided by both Student A and Student B with the resulting reasoning.

Both students are correct. Extending beyond these samples, real life pedigrees are oftentimes uncooperative in yielding up clear conclusions. Often times the pattern is ambiguous and can be argued multiple ways. However in these cases, I credit the student with the correct answer if she identifies the proper evidence and reasons through the process clearly.


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Inheritance Patterns (#6 of 6): Pedigrees

Unit 4: 3) Genetics ("Identity & Change")
Lesson 10 of 10

Objective: 1. Students will apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population. (HS-LS-3) 2. Students will understand that cells store and use genetic information to guide their functions. An organism’s genotype determines its phenotype. These traits can be dominant or recessive depending on the alleles found on their genes.

Big Idea: Nearly all human traits, even many diseases, are inherited in predictable ways. Using the tools of mathematics and modeling, these inheritance patterns can be properly deduced.

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Science, Heredity, Punnett Squares, incomplete dominance, Sex-linked, Genetics, genetics, pedigrees, Monohybrid Crosses, Dihybrid Crosses, Complete dominance
  55 minutes
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