Gene Linkage (Topic D3.2)

Essential Idea(s):  The inheritance of genes follows patterns that can be predicted. Genes may be linked or unlinked and are inherited accordingly.

 Unit Length: 3 Lessons (AHL only)

  Guiding Questions

◊ What patterns of inheritance exist in plants and animals?

◊ What is the molecular basis of inheritance patterns?

Materials:

Self-Teaching Slides (AHL)  Quizlet Vocab Set (AHL)
 Notes Template (AHL)
IB Statement(s) and Objective(s)

 

Additional Higher Level Topics

D3.2.16: Segregation and independent assortment of unlinked genes in meiosis

  • Describe random orientation and independent assortment
  • State the outcome of allele segregation during meiosis
  • State the difference between independent assortment of genes and segregation of alleles

 

D3.2.17: Punnett grids for predicting genotypic and phenotypic ratios in dihybrid crosses involving pairs of unlinked autosomal genes

  • Determine possible allele combinations in gametes for crosses involving two genes
  • Determine the predicted genotype and phenotype ratios of F1 and F2 offspring of dihybrid crosses
  • Define unlinked genes and explain why the 9:3:3:1 and 1:1:1:1 ratios only work on unlinked genes

 

D3.2.18: Loci of human genes and their polypeptide products

  • Use a database to explore the loci of specified genes and their respective polypeptide products
  • Define loci

 

D3.2.19: Autosomal gene linkage

D3.2.20: Recombinants in crosses involving two linked or unlinked genes

  • Distinguish linked from unlinked genes
  • Use correct notation to show alleles of linked genes
  • Construct a Punnett square to show the possible genotype and phenotype outcomes in a dihybrid cross involving linked genes
  • Explain how crossing over between linked genes can lead to genetic recombinants
  • Define genetic recombinant

 

D3.2.21: Use of a chi-squared test on data from dihybrid crosses

  • Calculate the chi square value to determine the significance of differences between the observed and expected results of a genetic cross
  • State the two possible hypotheses of a statistical test
  • Calculate a chi-square value to compare observed and expected results of a dihybrid genetic cross
Activities: ⓟ = podcast / ⍰ = inquiry 5 / ⓦ = Write it /  Ӕ = The academy  / Ⓡ = Read it

📄 Practice with worksheets: Dihybrid Punnett Squares (💁) 

Practice perfecting the skill of dihybrid Punnett Squares. Answer key included.

 

📄 Practice with worksheets: Chi-Square Practice Problems (💁)

Practice makes perfect! Chi-square tests are one of the more complex math processes in DP Bio. Take the time to practice — complete this worksheet of practice problems. (Answer Key)

 

Ⓛ (virtual): Modeling Inheritance with Hairy Fingers 

(💁/ 👭 max 2 [podcast only])

Good genetics starts with hairy fingers. Or at least it does in this activity. Follow the instructions to calculate a theoretical ratio with “actual” (virtual) results for the gene that determines hairy fingers. Then use a random gamete generator to see how we can predict the chances of offspring inheriting certain traits from their parents. As an extension, try taking these results and completing a chi-square test to mathematically compare the results.  

 

Ⓛ: A Big, Ambitious Activity to Model Sex-Linked Inheritance  (💁/ 👬 max: 3)

Thomas Hunt’s experiments on the common fruit fly changed the face of genetics. Follow in the experimental footsteps of his work with this model experiment. This is a time-intensive option, so partner up and read through the document carefully.