Table of contents

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 involving pea plants that are heterozygous for both seed shape (Rr) and seed color (Yy), what is the expected phenotypic ratio among the offspring?

3:1

1:2:1

9:3:3:1

1:1:1:1

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Verified step by step guidance

Identify the two traits involved in the dihybrid cross: seed shape (Rr) and seed color (Yy), where each trait has two alleles with one dominant and one recessive.

Determine the genotype of the parents: both are heterozygous for both traits, so their genotypes are RrYy.

Use the Punnett square method to find all possible combinations of alleles in the offspring by crossing RrYy x RrYy, which results in 16 possible genotype combinations.

Classify the offspring genotypes into phenotypes based on dominance: dominant seed shape (R) produces round seeds, recessive (r) produces wrinkled; dominant seed color (Y) produces yellow seeds, recessive (y) produces green.

Count the number of offspring for each phenotype category and express the ratio, which will be 9 round yellow : 3 round green : 3 wrinkled yellow : 1 wrinkled green, or 9:3:3:1.