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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
  31m
22. Evolutionary Genetics29m

2. Mendel's Laws of Inheritance

Dihybrid Cross

Genetics

2. Mendel's Laws of Inheritance

Dihybrid Cross

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Multiple Choice

In a dihybrid cross exhibiting complete genetic linkage, what would you expect regarding the phenotypic ratio of the offspring?

A 9:3:3:1 phenotypic ratio will be observed.

Only recombinant phenotypes will be observed in the offspring.

All four possible phenotypes will appear in equal proportions.

Only parental phenotypes will be observed in the offspring.

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Verified step by step guidance

Understand that a dihybrid cross typically involves two genes, each with two alleles, and when these genes assort independently, the classic phenotypic ratio is 9:3:3:1.

Recall that complete genetic linkage means the two genes are located very close together on the same chromosome and do not undergo recombination (crossing over) during meiosis.

Because of this linkage, the alleles are inherited together as a unit, so the offspring will only show the parental combinations of alleles, not recombinant types.

Therefore, instead of the 9:3:3:1 ratio, you expect only the parental phenotypes to appear in the offspring, typically in a 1:1 ratio if the parents are heterozygous for both genes.

Summarize that complete linkage prevents the formation of recombinant phenotypes, so the phenotypic ratio reflects only the parental types without any new combinations.