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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

X-Inactivation

Genetics

3. Extensions to Mendelian Inheritance

X-Inactivation

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Multiple Choice

Which statement best describes how X chromosomes are inactivated in female mammals?

One of the two X chromosomes in each cell is randomly inactivated during early embryonic development.

The paternal X chromosome is always inactivated in every cell.

Both X chromosomes are completely inactivated in all cells to prevent gene expression.

X-inactivation only occurs in male mammals to balance gene dosage.

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Verified step by step guidance

Understand the concept of X chromosome inactivation, which is a process that occurs in female mammals to balance the gene dosage between males (XY) and females (XX).

Recall that females have two X chromosomes, but to prevent having double the amount of X-linked gene products compared to males, one X chromosome in each cell is inactivated.

Recognize that this inactivation happens randomly in each cell during early embryonic development, meaning either the maternal or paternal X chromosome can be inactivated in different cells.

Note that this inactivation is stable and maintained in all descendant cells, leading to a mosaic pattern of X chromosome expression in females.

Eliminate incorrect options by understanding that the paternal X is not always inactivated, both X chromosomes are not completely inactivated, and X-inactivation does not occur in males.