Two heterozygous organisms are crossed, and the F 2 phenotypic ratio is 12:3:1. What form of epistasis do these two genes exhibit?

Okay. So this question, in this question, you just have to know the f two phenotypic ratios for various types of epistasis. So if you don't have those memorized, make sure you flip back through your handout and look at different ratios and try to memorize those because you will need to know them. But this question says, 2 heterozygous organisms are cross and the f two phenotypic ratio is 12 to 3 to 1. What form of epistasis do these two genes exhibit? And so, do you think it's dominant epistasis, recessive epistasis, suppressors, or complimentary gene action? Which one of these, produces an f two phenotypic ratio of 12 to 3 to 1? Right. The answer here is a. 12 to 3 to 1 represents a phenotypic ratio, if 2 genes are acting under dominant epistasis. So with that, let's move on.

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1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
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22. Evolutionary Genetics29m

3. Extensions to Mendelian Inheritance

Epistasis and Complementation

Genetics

3. Extensions to Mendelian Inheritance

Epistasis and Complementation

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Multiple Choice

Two heterozygous organisms are crossed, and the F₂ phenotypic ratio is 12:3:1. What form of epistasis do these two genes exhibit?

Dominant Epistasis

Recessive Epistasis

Suppressors

Complementary Gene Action

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Verified step by step guidance

Understand the concept of epistasis: Epistasis occurs when the effect of one gene is dependent on the presence of one or more 'modifier genes'. In this context, we are looking at how two genes interact to affect a phenotype.

Identify the phenotypic ratio: The given F2 phenotypic ratio is 12:3:1. This ratio is a key indicator of the type of epistasis at play.

Recall the typical phenotypic ratios associated with different types of epistasis: Dominant epistasis often results in a 12:3:1 ratio, where one dominant allele masks the effects of another gene.

Compare the given ratio with known epistatic ratios: The 12:3:1 ratio is characteristic of dominant epistasis, where the presence of a dominant allele in one gene masks the expression of alleles at a second gene.

Conclude the type of epistasis: Based on the comparison, the form of epistasis exhibited by these two genes is dominant epistasis, as the 12:3:1 ratio matches the expected outcome for this type of genetic interaction.