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

Probability and Genetics

Genetics

2. Mendel's Laws of Inheritance

Probability and Genetics

Previous problemNext problem

Struggling with Genetics?

Join thousands of students who trust us to help them ace their exams!Watch the first video

Multiple Choice

In a cross between two individuals who are both heterozygous for the autosomal recessive disorders phenylketonuria (PKU, gene 1) and cystic fibrosis (CF, gene 2), what proportion of their children will have either PKU or CF, but not both disorders?

3/16

7/16

9/16

6/16

Previous problemNext problem

Verified step by step guidance

Identify the genotypes of the parents for both genes. Since both parents are heterozygous for PKU and CF, their genotypes are PpCc, where 'P' and 'C' are the dominant (normal) alleles and 'p' and 'c' are the recessive alleles causing PKU and CF respectively.

Determine the possible gametes each parent can produce. Each parent can produce four types of gametes: PC, Pc, pC, and pc, each with equal probability (1/4).

Use a Punnett square to find the genotypic combinations of the offspring by crossing the gametes from both parents. This will give 16 possible genotype combinations (4x4).

Identify which genotypes correspond to having PKU only, CF only, both disorders, or neither. PKU occurs when the genotype is homozygous recessive for gene 1 (pp), CF occurs when homozygous recessive for gene 2 (cc). Having both disorders means the genotype is ppcc.

Calculate the proportion of offspring that have either PKU or CF but not both by summing the probabilities of genotypes with ppCc or Ppcc, and exclude ppcc. Express this as a fraction out of 16 total combinations.