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

6. Chromosomal Variation

Chromosomal Rearrangements: Overview

Genetics

6. Chromosomal Variation

Chromosomal Rearrangements: Overview

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Multiple Choice

In mammals, in which parent could a chromosomal rearrangement result in an X chromosome carrying two different fur color alleles?

The mother, due to X chromosome pairing and possible unequal crossing over during oogenesis

Neither parent, as X chromosomes cannot carry more than one fur color allele

The father, because he has only one X chromosome and can undergo X-X recombination

Both parents equally, since both can have two X chromosomes recombine

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Verified step by step guidance

Understand that in mammals, females have two X chromosomes (XX) while males have one X and one Y chromosome (XY). This difference is crucial for how chromosomal rearrangements can occur on the X chromosome.

Recognize that chromosomal rearrangements such as unequal crossing over can happen during meiosis, the process that produces gametes (eggs and sperm). In females, meiosis occurs during oogenesis, where the two X chromosomes can pair and potentially exchange genetic material.

Note that in males, since there is only one X chromosome and one Y chromosome, there is no homologous X chromosome to pair with during meiosis, so X-X recombination cannot occur in spermatogenesis.

Conclude that only the mother can produce an X chromosome carrying two different alleles for fur color due to the possibility of unequal crossing over between her two X chromosomes during oogenesis.

Therefore, the key concept is that the presence of two X chromosomes in females allows for recombination events that can create novel allele combinations on a single X chromosome, which is not possible in males.