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
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
3. Extensions to Mendelian Inheritance
Organelle DNA
Struggling with Genetics?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which of the following best explains why genes located in mitochondria and chloroplasts do not exhibit Mendelian patterns of inheritance?
A
They are only expressed in somatic cells and not passed to offspring.
B
They are always silenced by nuclear gene regulation.
C
They are inherited primarily through the maternal lineage, rather than through both parents equally.
D
They undergo frequent recombination during meiosis, leading to unpredictable inheritance.

1
Understand that Mendelian inheritance typically involves genes located in the nucleus, where alleles segregate and assort independently during meiosis, leading to predictable inheritance patterns.
Recognize that mitochondria and chloroplasts have their own DNA, separate from nuclear DNA, and these organelles are inherited differently compared to nuclear genes.
Recall that mitochondria and chloroplasts are usually inherited maternally because the egg contributes most of the cytoplasm (and thus these organelles) to the offspring, while the sperm contributes very little or none.
Note that because of this maternal inheritance, genes in mitochondria and chloroplasts do not follow the typical Mendelian patterns of inheritance, which assume biparental contribution of alleles.
Conclude that the key reason for non-Mendelian inheritance of mitochondrial and chloroplast genes is their uniparental (maternal) inheritance, rather than recombination or gene silencing.
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Related Practice
Multiple Choice
In bacteria, what typically happens to linear DNA that is not integrated into the bacterial chromosome?
2
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