Gene Interactions

By A.K. Matai

Genes can and do interact with one another (usually through biochemical pathways). These genes can be on the same chromosome or on different chromosomes. In this post, I will cover three important gene interactions and how they affect the 9:3:3:1.

Premise 

In werewolves, the PUP gene determines pigment (IP) or no pigment (INP) while the FUR gene determines the color of the pigment which can be black (E), black with white spots (ES), or red (e).

 Scenario 1

What are the genotypes, phenotypes, and ratios would you expect in the F1 and F2 generations if you began with the following parents and these genetic interactions:

                          IP / IP; E / E x INP / INP; ES / ES

  • the E allele is completely dominant to the ES allele
  • the INP allele is completely dominant to the IP allele
  • the I-gene is dominantly epistatic to the E-gene

Dominant epistasis – the dominant allele at one locus masks the phenotype of the second locus.

Gene Interactions 1

Scenario 2

What are the genotypes, phenotypes, and ratios would you expect in the F1 and F2 generations if you began with the following parents and these genetic interactions:

IP/ IP; E / E x INP/ INP; e / e

  • the E allele is completely dominant to the e allele
  • the IP allele is completely dominant to the INP allele
  • the I-gene is recessively epistatic to the E-gene

Recessive epistasis – two recessive alleles at one locus masks the phenotype of the second locus.

Gene Interactions 3

Scenario 3

What are the genotypes, phenotypes, and ratios would you expect in the F1 and F2 generations if you began with the following parents and these genetic interactions:

IP/ IP; e / e x INP/ INP; ES/ ES

  • the ES and e alleles show incomplete dominance
  • the IP allele is completely dominant to the INP allele
  • the I-gene is recessively epistatic to the E-gene

Recessive epistasis – two recessive alleles at one locus masks the phenotype of the second locus. In this case, the two alleles show incomplete dominance which further affects the 9:3:3:1.

Gene Interactions 2

Questions, Comments or Concerns?

Feel free to post a your questions, comments or concerns down below!

References

Locke, John; Deyholos, Michael; Harrington, Michael; Canham, Lindsay; Kang, Min, “Open Genetics Lectures (OGL) Fall 2016”

 

Unknown. DNA Microscopic Cell Gene Helix Science Medical. 2017. https://pixabay.com/p-1903319/?no_redirect. Web. 19 Mar. 2017.

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