Skip to main content
Pearson+ LogoPearson+ Logo
Ch. 9 - Extranuclear Inheritance
All textbooksKlug 12th EditionCh. 9 - Extranuclear InheritanceProblem 20
Previous problem
Next problem
Chapter 9, Problem 20

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 that heteroplasmy refers to the presence of more than one type of mitochondrial DNA (mtDNA) within a cell or individual.
Recognize that mtDNA is inherited maternally, meaning it is passed down from the mother to her offspring.
Consider that one source of heteroplasmy could be mutations that occur in mtDNA over time, leading to a mixture of normal and mutated mtDNA within cells.
Another potential source of heteroplasmy is the inheritance of different mtDNA variants from the mother, which can occur if the mother herself has heteroplasmic mtDNA.
Reflect on the fact that during the development of the egg cell, a bottleneck effect can occur, leading to a random assortment of mtDNA variants, which may contribute to heteroplasmy in the offspring.

Verified Solution

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

Key Concepts

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

Mitochondrial DNA (mtDNA)

Mitochondrial DNA (mtDNA) is the genetic material found in mitochondria, the energy-producing organelles in cells. Unlike nuclear DNA, mtDNA is inherited maternally and is present in multiple copies within each mitochondrion. Variations in mtDNA can lead to heteroplasmy, where different mtDNA sequences coexist within an individual, influencing cellular function and health.
Recommended video:
Guided course
04:11
Organelle DNA Characteristics

Heteroplasmy

Heteroplasmy refers to the presence of more than one type of mitochondrial DNA within a single cell or individual. This condition can arise from mutations in mtDNA or from the mixing of mtDNA from different maternal lineages. Heteroplasmy can affect the expression of mitochondrial diseases and is a key factor in understanding mitochondrial genetics and inheritance patterns.
Recommended video:
Guided course
04:11
Organelle DNA Characteristics

Sources of Heteroplasmy

Heteroplasmy can originate from several sources, including mutations that occur during DNA replication or damage from environmental factors, leading to a mix of normal and mutated mtDNA. Additionally, the maternal inheritance of mtDNA can introduce variations, as different eggs may carry distinct mtDNA populations. These sources contribute to the genetic diversity observed in healthy individuals.
Recommended video:
Guided course
04:11
Organelle DNA Characteristics
Previous problem
Next problem
Related Practice
Textbook Question

Mutations in mitochondrial DNA appear to be responsible for a number of neurological disorders, including myoclonic epilepsy and ragged-red fiber disease, Leber's hereditary optic neuropathy, and Kearns-Sayre syndrome. In each case, the disease phenotype is expressed when the ratio of mutant to wild-type mitochondria exceeds a threshold peculiar to each disease, but usually in the 60 to 95 percent range.

Given that these are debilitating conditions, why has no cure been developed? Can you suggest a general approach that might be used to treat, or perhaps even cure, these disorders?

515
views
Textbook Question

Mutations in mitochondrial DNA appear to be responsible for a number of neurological disorders, including myoclonic epilepsy and ragged-red fiber disease, Leber's hereditary optic neuropathy, and Kearns-Sayre syndrome. In each case, the disease phenotype is expressed when the ratio of mutant to wild-type mitochondria exceeds a threshold peculiar to each disease, but usually in the 60 to 95 percent range.

Compared with the vast number of mitochondria in an embryo, the number of mitochondria in an ovum is relatively small. Might such an ooplasmic mitochondrial bottleneck present an opportunity for therapy or cure? Explain.

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?

245
views
Textbook Question

As mentioned in Section 9.3, 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.

237
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?

367
views