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

4. Genetic Mapping and Linkage

Crossing Over and Recombinants

Genetics

4. Genetic Mapping and Linkage

Crossing Over and Recombinants

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Multiple Choice

Sister chromatids present at metaphase II might not be genetically identical to each other because:

crossing over between homologous chromosomes occurred during prophase I

chromatids separate randomly during anaphase II

centromeres divide unevenly during meiosis I

DNA replication introduces errors during S phase

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Verified step by step guidance

Understand the context: Sister chromatids are the two identical copies of a single chromosome that are connected by a centromere. They are formed during DNA replication in the S phase and are expected to be genetically identical before meiosis II.

Recall the stages of meiosis: Meiosis consists of two divisions, meiosis I and meiosis II. During prophase I, homologous chromosomes pair up and exchange genetic material through crossing over, which creates new combinations of alleles.

Analyze the effect of crossing over: Crossing over occurs between homologous chromosomes (not sister chromatids) during prophase I. This process results in sister chromatids that are no longer identical because segments of DNA have been exchanged between homologous chromosomes.

Evaluate other options: Random separation of chromatids during anaphase II does not change their genetic content, centromeres dividing unevenly does not affect genetic identity of chromatids, and DNA replication errors are rare and not the main reason for differences between sister chromatids at metaphase II.

Conclude that the key reason sister chromatids might not be genetically identical at metaphase II is due to crossing over between homologous chromosomes during prophase I, which reshuffles genetic material before the chromatids separate.