Don't Be a Square: Punnett Squares are Used to Predict Genetic Trait Inheritance

Learning Resource Type

Classroom Resource

Subject Area

Science

Grade(s)

9, 10, 11, 12

Overview

After watching video clips from the Harry Potter and the Goblet of Fire movie, students explore the use of Punnett squares to predict genetic trait inheritance. The objective of this lesson is to articulate concepts related to genetics through direct immersive interaction. Students will describe a trait and give examples; understand the relationship between alleles and heterozygous and homozygous traits; create a 2 x 2 Punnett square and predict traits passed from parents to children; and describe nanotechnology research and engineering in genetics.

Science (2015) Grade(s): 09-12 - Biology

SC15.BIO.11

Analyze and interpret data collected from probability calculations to explain the variation of expressed traits within a population.

UP:SC15.BIO.11

Vocabulary

  • Genetics
  • Allele
  • Dominant
  • Recessive
  • Homozygous
  • Heterozygous
  • Genotype
  • Phenotype
  • Law of segregation
  • Hybrid
  • Law of independent assortment
  • F1 and F2 generations
  • Monohybrid
  • Dihybrid
  • Punnet square
  • Probability
  • Crossing over
  • Genetic recombination
  • Carrier
  • Pedigree
  • Incomplete dominance
  • Codominance
  • Multiple alleles
  • Epistasis
  • Sex chromosome
  • Autosome
  • Sex-linked trait
  • Polygenic trait

Knowledge

Students know:
  • Inheritable genetic variations may result from: new genetic combinations through meiosis, viable errors occurring during replication, and mutations caused by environmental factors.
  • Variations in genetic material naturally result during meiosis when corresponding sections of chromosome pairs exchange places.
  • Genetic material is inheritable.
  • Genetic variations produced by mutations and meiosis are inheritable.
  • The difference between genotypic and phenotypic ratios and percentages.
  • Examples of genetic crosses that do not fit traditional inheritance patterns (e.g., incomplete dominance, co-dominance, multi-allelic, polygenic) and explanations as to how the observed phenotypes are produced.
  • Mendel's laws of segregation and independent assortment.
  • Pedigrees can be used to infer genotypes from the observation of genotypes.
  • By analyzing a person's family history or a population study, disorders in future offspring can be predicted.

Skills

Students are able to:
  • Perform and use appropriate statistical analysis of data, including probability measures to determine the relationship between a trait's occurrence within a population and environmental factors.
  • Differentiate between homozygous and heterozygous allele pairings.
  • Create Punnett squares to predict offspring genotypic and phenotypic ratios.
  • Explain the relationship between the inherited genotype and the visible trait phenotype.
  • Examine genetic crosses that do not fit traditional inheritance patterns (incomplete dominance and co-dominance).
  • Use chromosome models to physically demonstrate the points in meiosis where Mendel's laws of segregation and independent assortment are observed.
  • Analyze pedigrees to identify the patterns of inheritance for specific traits/ disorders including autosomal dominant/ recessive as well as sex-linked and mitochondrial patterns.

Understanding

Students understand that:
  • In sexual reproduction, chromosomes can sometimes swap sections during the process of meiosis, thereby creating new genetic combinations and thus more genetic variation.
  • Although DNA replication is tightly regulated and remarkably accurate, errors do occur and result in mutations, which are also a source of genetic variation.
  • Environmental factors can also cause mutations in genes, and viable mutations are inherited.
  • Environmental factors also affect expression of traits, and hence affect the probability of occurrences of traits in a population.
  • The variation and distribution of traits observed depends on both genetic and environmental factors.

Scientific and Engineering Practices

Developing and Using Models; Analyzing and Interpreting Data; Using Mathematics and Computational Thinking

Crosscutting Concepts

Patterns; Systems and System Models
Science (2015) Grade(s): 09-12 - Biology

SC15.BIO.11a

Use mathematics and computation to predict phenotypic and genotypic ratios and percentages by constructing Punnett squares, including using both homozygous and heterozygous allele pairs.

CR Resource Type

Lesson/Unit Plan

Resource Provider

TeachEngineering from the University of Colorado Boulder

License Type

Custom

Accessibility

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