Skip to main content
Pearson+ LogoPearson+ Logo
Ch. 9 - Extranuclear Inheritance
Klug - Concepts of Genetics 12th Edition
Klug12th EditionConcepts of Genetics ISBN: 9780135564776Not the one you use?Change textbook
All textbooksKlug 12th EditionCh. 9 - Extranuclear InheritanceProblem 20a
Chapter 9, Problem 20a

Payne, B. A. et al. (2013) present evidence that a low level of heteroplasmic mtDNA exists in all tested healthy individuals.
What are two likely sources of such heteroplasmy?

Verified step by step guidance
1
Understand the concept of heteroplasmy: Heteroplasmy refers to the presence of more than one type of mitochondrial DNA (mtDNA) within a single cell or individual. This can occur due to mutations or inheritance of different mtDNA variants.
Identify the first likely source: Mutations in mtDNA can occur spontaneously during replication or as a result of environmental factors such as oxidative stress. These mutations can lead to the coexistence of different mtDNA sequences within the same cell.
Identify the second likely source: Heteroplasmy can also arise through maternal inheritance. During fertilization, the mitochondria (and their DNA) are inherited almost exclusively from the mother. If the mother has a mix of mtDNA variants, this heteroplasmy can be passed down to the offspring.
Consider the role of mitochondrial bottleneck: During early development, a small subset of the mother's mitochondria is selected to populate the developing embryo. This bottleneck effect can amplify pre-existing heteroplasmy, making it detectable in healthy individuals.
Summarize the findings: The two likely sources of heteroplasmy in healthy individuals are (1) spontaneous or environmentally induced mutations in mtDNA and (2) inheritance of mixed mtDNA populations from the mother, potentially amplified by the mitochondrial bottleneck effect.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Heteroplasmy

Heteroplasmy refers to the presence of more than one type of mitochondrial DNA (mtDNA) within a single cell or individual. This condition can arise from mutations in mtDNA, leading to a mixture of normal and mutated genomes. Understanding heteroplasmy is crucial for studying mitochondrial diseases and the overall genetic diversity within populations.
Recommended video:
Guided course
04:11
Organelle DNA Characteristics

Mitochondrial DNA (mtDNA)

Mitochondrial DNA is the genetic material found in mitochondria, the energy-producing organelles in cells. Unlike nuclear DNA, mtDNA is inherited maternally and is more prone to mutations due to its proximity to reactive oxygen species generated during cellular respiration. The study of mtDNA is essential for understanding inheritance patterns and the role of mitochondria in health and disease.
Recommended video:
Guided course
04:11
Organelle DNA Characteristics

Sources of Heteroplasmy

Heteroplasmy can arise from various sources, including mutations that occur during DNA replication or damage from environmental factors such as toxins and radiation. Additionally, the mixing of mtDNA from different maternal lineages during fertilization can contribute to heteroplasmy. Identifying these sources helps researchers understand the dynamics of mitochondrial genetics and its implications for health.
Recommended video:
Guided course
04:11
Organelle DNA Characteristics
Related Practice
Textbook Question

Researchers examined a family with an interesting distribution of Leigh syndrome symptoms. In this disorder, individuals may show a progressive loss of motor function (ataxia, A) with peripheral neuropathy (PN, meaning impairment of the peripheral nerves). A mitochondrial DNA (mtDNA) mutation that reduces ATPase activity was identified in various tissues of affected individuals. The accompanying table summarizes the presence of symptoms in an extended family.

Provide an explanation for the pattern of inheritance of the disease. What term describes this pattern?

474
views
Textbook Question

Researchers examined a family with an interesting distribution of Leigh syndrome symptoms. In this disorder, individuals may show a progressive loss of motor function (ataxia, A) with peripheral neuropathy (PN, meaning impairment of the peripheral nerves). A mitochondrial DNA (mtDNA) mutation that reduces ATPase activity was identified in various tissues of affected individuals. The accompanying table summarizes the presence of symptoms in an extended family.

How can some individuals in the same family show such variation in symptoms? What term, as related to organelle heredity, describes such variation?

533
views
Textbook Question

Researchers examined a family with an interesting distribution of Leigh syndrome symptoms. In this disorder, individuals may show a progressive loss of motor function (ataxia, A) with peripheral neuropathy (PN, meaning impairment of the peripheral nerves). A mitochondrial DNA (mtDNA) mutation that reduces ATPase activity was identified in various tissues of affected individuals. The accompanying table summarizes the presence of symptoms in an extended family.

In what way does a condition caused by mtDNA differ in expression and transmission from a mutation that causes albinism?

478
views
Textbook Question

Payne, B. A. et al. (2013) present evidence that a low level of heteroplasmic mtDNA exists in all tested healthy individuals.

What genetic conditions within a given mitochondrion are likely to contribute to such a variable pool of mitochondria?

409
views
Textbook Question

The mtDNA accumulates mutations at a rate approximately ten times faster than nuclear DNA. Thus geneticists can use mtDNA variations as a 'molecular clock' to study genetic variation and the movement of ancestral human populations from Africa to different areas of the world more than 125,000 years ago. Propose an explanation for how an analysis of mtDNA can be used to construct family trees of human evolution.

404
views
Textbook Question

Because offspring inherit the mitochondrial genome only from the mother, evolutionarily the mitochondrial genome in males encounters a dead end. The mitochondrial genome in males has no significant impact on the genetic information of future generations. Scientists have proposed that this can result in an accumulation of mutations that have a negative impact on genetic fitness of males but not females. Experiments with Drosophila support this possibility. What experimental data or evidence would you want to evaluate or consider to determine if an accumulation of mtDNA mutations negatively impacts the fitness of males of any species?

707
views