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
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
2. Mendel's Laws of Inheritance
Probability and Genetics
Problem 41e
Textbook Question
Humans vary in many ways from one another. Among many minor phenotypic differences are the following five independently assorting traits that (sort of) have a dominant and a recessive phenotype: (1) forearm hair (alleles F and f )—the presence of hair on the forearm is dominant to the absence of hair on the forearm; (2) earlobe form (alleles E and e)—unattached earlobes are dominant to attached earlobes; (3) widow's peak (alleles W and w)—a distinct 'V' shape to the hairline at the top of the forehead is dominant to a straight hairline; (4) hitchhiker's thumb (alleles H and h)—the ability to bend the thumb back beyond vertical is dominant and the inability to do so is recessive; and (5) freckling (alleles D and d)—the appearance of freckles is dominant to the absence of freckles. In reality, the genetics of these traits are more complicated than single gene variation, but assume for the purposes of this problem that the patterns in families match those of other single-gene variants.
If a couple with the genotypes Ff Ee Ww Hh Dd and Ff Ee Ww Hh Dd have children, what is the chance the children will inherit the following characteristics?
four dominant traits and one recessive trait
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1
Identify the genotypes of the parents: both are Ff Ee Ww Hh Dd.
Determine the possible gametes each parent can produce. Each parent can produce 2^5 = 32 different combinations of alleles, as each trait has two alleles.
List the possible combinations of four dominant traits and one recessive trait. For example, one such combination could be F E W H d.
Calculate the probability of each specific combination of four dominant and one recessive trait occurring in a child. This involves multiplying the probabilities of inheriting each allele from the parents.
Sum the probabilities of all possible combinations that result in four dominant traits and one recessive trait to find the overall probability.
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