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

3. Extensions to Mendelian Inheritance

Understanding Independent Assortment

Genetics

3. Extensions to Mendelian Inheritance

Understanding Independent Assortment

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

Which of the following provides the best evidence that Irene was heterozygous for hemophilia?

All of her children were unaffected by hemophilia.

She had no family history of hemophilia.

She exhibited symptoms of hemophilia throughout her life.

She had children, some of whom were affected by hemophilia and some who were not.

Previous problemNext problem

Verified step by step guidance

Understand that hemophilia is a sex-linked recessive disorder, typically carried on the X chromosome. Females have two X chromosomes, so to be affected, they must have two copies of the hemophilia allele, while males have only one X chromosome and will be affected if they inherit the hemophilia allele.

Recognize that a heterozygous female (carrier) has one normal allele and one hemophilia allele on her X chromosomes. She usually does not show symptoms because the normal allele is dominant.

Analyze the inheritance pattern: a heterozygous mother can pass either the normal or the hemophilia allele to her children. Sons who inherit the hemophilia allele will be affected, while daughters who inherit it will be carriers if they receive a normal allele from their father.

Evaluate the evidence: if Irene had children some of whom were affected by hemophilia and some who were not, this indicates she must have carried one hemophilia allele and one normal allele, making her heterozygous.

Conclude that the presence of both affected and unaffected children is the best evidence of Irene's heterozygosity for hemophilia, as it reflects the expected Mendelian inheritance of a sex-linked recessive trait from a carrier mother.