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

Sex-Linked Genes

Genetics

2. Mendel's Laws of Inheritance

Sex-Linked Genes

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Multiple Choice

In cats, the gene for fur color is located on the X chromosome, with the alleles B (black) and O (orange). Which of the following fur colors are possible in female cats due to X-inactivation?

Orange

Tortoiseshell (black and orange patches)

White

Black

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Verified step by step guidance

Understand that female cats have two X chromosomes (XX), so they can carry two different alleles for fur color: B (black) and O (orange).

Recall that X-inactivation is a process where one of the two X chromosomes in each cell of a female is randomly inactivated, leading to mosaic expression of X-linked genes.

Recognize that if a female cat is heterozygous (X^B X^O), X-inactivation will cause some cells to express the B allele and others to express the O allele, resulting in patches of black and orange fur.

Identify that this patchy fur pattern is called tortoiseshell, which is unique to heterozygous females due to X-inactivation.

Note that females homozygous for B (X^B X^B) will be black, homozygous for O (X^O X^O) will be orange, and white fur is not explained by this gene, so tortoiseshell is the only color pattern caused by X-inactivation.