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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

Why is the normal range for the mass of DNA in a male cat cell lower than that in a female cat?

Female cats lose DNA during X-inactivation, reducing their DNA mass below that of males.

Male cats have more mitochondrial DNA than female cats, decreasing their nuclear DNA mass.

Male cats have fewer autosomes than female cats, resulting in less total DNA.

Male cats have only one X chromosome, while female cats have two, increasing the total DNA content in females.

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Verified step by step guidance

Understand that the total DNA content in a cell depends on the number and type of chromosomes present.

Recall that female cats have two X chromosomes (XX), while male cats have one X and one Y chromosome (XY).

Recognize that the X chromosome is relatively large and contains many genes, contributing significantly to the total DNA mass.

Note that although one of the female's X chromosomes undergoes X-inactivation, the DNA itself is still present; X-inactivation silences gene expression but does not remove DNA.

Conclude that because females have two X chromosomes and males have only one, the total DNA mass in female cat cells is higher than in male cat cells.