Non-Medellin Inheritance Part 2 (Medium)
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Questions and Answers

What is the main function of mitochondria?

  • Fatty acid synthesis
  • Protein synthesis
  • Cell signaling
  • Oxidative phosphorylation (correct)

How many base pairs make up the human mitochondrial DNA (mtDNA)?

  • 20,000 bp
  • 30,000 bp
  • 17,000 bp (correct)
  • 10,000 bp

What is the primary location where most mitochondrial proteins are encoded?

  • Nuclear DNA (correct)
  • Cytoplasmic DNA
  • Chloroplast DNA
  • Mitochondrial DNA

What is the range of variation in the size of mitochondrial genomes among different species?

<p>400-fold (B)</p> Signup and view all the answers

What is the byproduct of oxygen consumption during ATP synthesis in mitochondria?

<p>Water (A)</p> Signup and view all the answers

Which of the following is NOT a component of human mitochondrial DNA?

<p>mRNA genes (C)</p> Signup and view all the answers

What is the pattern of inheritance of mitochondria and chloroplasts in Angiosperms?

<p>Often maternal inheritance, although biparental inheritance is among some species (C)</p> Signup and view all the answers

Which of the following is a mechanism responsible for maternal inheritance of mitochondria?

<p>Lack of entry of sperm mitochondria into the cytoplasm of the egg (C)</p> Signup and view all the answers

What is the inheritance pattern of mitochondria in Mammals?

<p>Maternal inheritance (D)</p> Signup and view all the answers

In Chlamydomonas, which mating type passes on its mitochondria to the offspring?

<p>mt+ (A)</p> Signup and view all the answers

What is the fate of sperm mitochondrial DNA during sperm maturation in Drosophila?

<p>It is cleaved and destroyed by an endonuclease (B)</p> Signup and view all the answers

In Gymnosperms, which parent contributes mitochondria and chloroplasts to the offspring?

<p>Father (C)</p> Signup and view all the answers

What happens to paternal mitochondria that enter the egg during fertilization?

<p>They are modified by ubiquitin and targeted for destruction (D)</p> Signup and view all the answers

How is human mtDNA transmitted to offspring?

<p>Through the egg cytoplasm from the female parent (C)</p> Signup and view all the answers

Why do mitochondrial DNA mutations not typically affect the offspring in animals?

<p>Because mechanisms exist to eliminate sperm mitochondrial DNA (D)</p> Signup and view all the answers

Which of the following is NOT a mechanism of maternal inheritance of mitochondria?

<p>Mitochondrial DNA replication during embryonic development (A), Random segregation of mitochondria during meiosis (B)</p> Signup and view all the answers

Why are mitochondria highly susceptible to DNA damage?

<p>Due to high oxygen consumption leading to free radicals (B)</p> Signup and view all the answers

What is a common characteristic of human mitochondrial diseases?

<p>They are chronic and degenerative (C)</p> Signup and view all the answers

What is heteroplasmy in the context of mitochondrial disease?

<p>A mixed population of mitochondria with and without mutations (D)</p> Signup and view all the answers

What is the main goal of the three-parent baby reproductive technology?

<p>To prevent the transmission of mitochondrial diseases from mother to child (B)</p> Signup and view all the answers

Which of the following is an example of a human mitochondrial disease?

<p>Leber hereditary optic neuropathy (D)</p> Signup and view all the answers

What is the consequence of a high ratio of mutant to normal mitochondria in a cell?

<p>The cell develops a mitochondrial disease (C)</p> Signup and view all the answers

How do mitochondrial mutations accumulate over time?

<p>Through the accumulation of DNA damage in somatic cells (D)</p> Signup and view all the answers

What is the resulting pattern of inheritance for human mitochondrial diseases?

<p>Strict maternal inheritance (B)</p> Signup and view all the answers

Flashcards

Ubiquitin

A small regulatory protein that targets organelle destruction, specifically breaking down paternal mitochondria that enter the egg.

Destruction of Sperm Mitochondria

The process by which paternal mitochondria entering the egg are eliminated.

Maternal Inheritance of Mitochondria

The transmission of human mitochondrial DNA (mtDNA) solely from the mother to offspring.

Human Mitochondrial Diseases

Genetic disorders resulting from mutations in mitochondrial DNA that affect cellular energy production.

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Heteroplasmy

A common characteristic of mitochondrial diseases where cells contain a mix of normal and mutated mitochondria.

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Threshold Value

The ratio of mutated to normal mitochondria that triggers the onset of mitochondrial disease symptoms.

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Three-Parent Babies

A reproductive technology that uses a donor's healthy mitochondria to prevent transmission of mitochondrial diseases from the mother to her child.

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Lack of Entry of Sperm Mitochondria

The lack of paternal mitochondria entering the egg, ensuring maternal mitochondria are inherited.

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Destruction of Sperm mtDNA Prior to Fertilization

The process by which paternal mitochondrial DNA is broken down before fertilization, preventing its inheritance by offspring.

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Oxidative Phosphorylation

The process where cellular respiration occurs, generating energy (ATP) for cellular functions.

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Mitochondrial DNA (mtDNA)

The circular DNA molecule found in mitochondria, containing genes for rRNA, tRNA, and some proteins involved in oxidative phosphorylation.

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Nuclear-Encoded Mitochondrial Proteins

The majority of mitochondrial proteins are encoded by genes in the nuclear genome and are synthesized in the cytoplasm before being transported to mitochondria for function.

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Leber Hereditary Optic Neuropathy

A human mitochondrial disease caused by mutations in genes encoding respiratory chain proteins, affecting vision.

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Neurogenic Muscle Weakness

A human mitochondrial disease caused by mutations in the ATPase6 gene, leading to muscle weakness.

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Mitochondrial Myopathy and Maternal Myopathy and Cardiomyopathy

A human mitochondrial disease characterized by muscle and heart problems, caused by mutations in genes encoding tRNA for leucine.

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Sizes of Organellar Genomes

The range in size of organellar genomes across different species.

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Small Size of Mitochondrial Genomes in Animals

The relatively small size of mitochondrial genomes in animals.

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Intermediate Size of Mitochondrial Genomes in Fungi and Protists

The intermediate size of mitochondrial genomes in fungi and protists.

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Large Size of Mitochondrial Genomes in Plants

The relatively large size of mitochondrial genomes in plants.

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Destruction of Sperm Mitochondria After Fertilization

The process by which sperm mitochondria are destroyed after fertilization, preventing their inheritance.

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Mitochondrial Function

The key role of mitochondria in generating energy (ATP) for cellular processes.

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Pioneers of Three-Parent Babies Technology

John Zhang and colleagues are pioneers in the development of mitochondrial replacement therapy for preventing the transmission of mitochondrial diseases.

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Study Notes

Destruction of Sperm Mitochondria After Fertilization

  • Paternal mitochondria that enter the egg are modified by ubiquitin, a small regulatory protein that targets organelle destruction
  • This process occurs in most mammals, including humans

Maternal Inheritance of Mitochondria

  • Human mtDNA is transmitted from the female parent to offspring via the cytoplasm of the egg
  • Therefore, the transmission of human mitochondrial diseases follows a strict maternal inheritance pattern

Human Mitochondrial Diseases

  • Over 200 human mitochondrial diseases have been identified
  • These diseases are typically chronic degenerative disorders affecting cells requiring high levels of ATP, such as nerve and muscle cells
  • Examples of human mitochondrial diseases include:
    • Leber hereditary optic neuropathy, caused by mutations in mitochondrial genes encoding respiratory chain proteins
    • Neurogenic muscle weakness, caused by mutations in the ATPase6 gene
    • Mitochondrial myopathy and maternal myopathy and cardiomyopathy, caused by mutations in genes encoding tRNA for leucine

Heteroplasmy in Mitochondrial Disease

  • Heteroplasmy is an important factor in mitochondrial disease, where cells can contain a mixed population of mitochondria, some with disease-causing mutations and others without
  • The ratio of mutant to normal mitochondria can exceed a threshold value, leading to disease symptoms that may vary widely within a given family

Three Parent Babies

  • A new reproductive technology has emerged to prevent the transmission of mitochondrial diseases from mothers to their offspring
  • This technology was pioneered by John Zhang and colleagues in 2016, and involves replacing the mother's mitochondria with those from a donor woman

Mechanisms of Maternal Inheritance

  • There are three mechanisms responsible for maternal inheritance of mitochondria:
    • Lack of entry of sperm mitochondria into the egg
    • Destruction of sperm mitochondrial DNA prior to fertilization
    • Destruction of sperm mitochondria after fertilization

Sizes of Organellar Genomes

  • The sizes of organellar genomes vary greatly among different species, with a 400-fold variation in the size of mitochondrial genomes
  • Mitochondrial genomes are fairly small in animals, intermediate in size in fungi and protists, and fairly large in plants

Mitochondrial DNA

  • The main function of mitochondria is oxidative phosphorylation, which generates ATP (adenosine triphosphate) for cellular reactions
  • Human mitochondrial DNA (mtDNA) consists of only 17,000 bp and includes genes for rRNA, tRNA, and 13 polypeptides involved in oxidative phosphorylation
  • Most mitochondrial proteins are encoded by genes in the nucleus and are made in the cytoplasm before being transported into the mitochondria

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Non-Mendelian Inheritance Part II Lecture PDF

Description

This quiz covers the process of destruction of sperm mitochondria after fertilization in mammals, including humans, and the role of ubiquitin in this process.

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