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Mitochondrial DNA Overview
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Mitochondrial DNA Overview

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@StableEpilogue

Questions and Answers

Which statement is true about mitochondrial disease caused by nuclear genome mutations?

  • They can be caused by defects in genes responsible for mitochondrial replication, transcription, and repair. (correct)
  • They can be caused solely by defects in mitochondrial DNA.
  • They follow unique inheritance patterns not related to Mendelian disorders.
  • They are exclusively linked to environmental factors.

    • Friedreich Ataxia is an example of which type of mitochondrial disorder?

  • Mitochondrial disease associated with chromosomal abnormalities.
  • Purely mitochondrial disease caused by mitochondrial DNA mutations.
  • Mitochondrial disease caused by nuclear genome mutations. (correct)
  • Mitochondrial disease dependent on environmental factors.

    • Which of the following symptoms is NOT associated with Parkinson's Disease?

  • Limb ataxia (correct)
  • Tremor
  • Rigidity
  • Postural instability

    • What is the incidence rate of Parkinson's Disease in the population?

    <p>1-2%</p> Signup and view all the answers

    What role does Parkin play in mitochondria when there is damage?

    <p>It triggers autophagy to remove dysfunctional mitochondria.</p> Signup and view all the answers

    Which gene is NOT mentioned as being involved in Parkinson's Disease?

    <p>FXN</p> Signup and view all the answers

    What characterizes the unstable GAA expansion in Friedreich Ataxia?

    <p>It leads to defective iron trafficking within mitochondria.</p> Signup and view all the answers

    Mitochondrial dysfunction dependence signifies that mitochondrial diseases are primarily caused by what?

    <p>Genetic defects affecting mitochondrial monitoring and regulation.</p> Signup and view all the answers

    What type of DNA structure is found in mitochondria?

    <p>Circular and double-stranded</p> Signup and view all the answers

    How many polypeptides are encoded by mitochondrial DNA?

    <p>13</p> Signup and view all the answers

    Which term describes a mitochondrial state where all DNA copies are identical?

    <p>Homoplasmy</p> Signup and view all the answers

    Which functions are nuclear-derived proteins NOT involved in regarding mitochondrial function?

    <p>Replication of nuclear DNA</p> Signup and view all the answers

    What is the relationship between mitochondrial DNA and nuclear DNA?

    <p>Mitochondrial DNA replicates independently from nuclear DNA</p> Signup and view all the answers

    How many types of RNA are encoded by mitochondrial DNA?

    <p>22</p> Signup and view all the answers

    Which of these statements about heteroplasmy is accurate?

    <p>More than one genetic variant of mitochondrial DNA is present.</p> Signup and view all the answers

    Which component is encoded by mitochondrial DNA specifically related to protein synthesis?

    <p>All of the above</p> Signup and view all the answers

    What is one significant challenge in establishing links between mitochondrial variants and complex diseases?

    <p>Most links are correlative and hard to validate functionally</p> Signup and view all the answers

    Which effect describes cancer cells' preference for glucose metabolism in the presence of oxygen?

    <p>Warburg Effect</p> Signup and view all the answers

    What phenomenon is primarily used in diagnosing solid tumors due to their high glucose metabolism?

    <p>FDG accumulation detected by positron emission tomography</p> Signup and view all the answers

    What is a noted association of mt-ND3 mutation according to research?

    <p>Associated with breast cancer</p> Signup and view all the answers

    How does the impairment of oxidative phosphorylation influence tumor cells as proposed in cancer theories?

    <p>Down regulates apoptosis through the AKT cell survival pathway</p> Signup and view all the answers

    Which mitochondrial mutation is associated with prostate cancer based on prior findings?

    <p>Mt-CO1 mutation</p> Signup and view all the answers

    What impact does a mouse model with mt-ND5 mutation have on tumor growth?

    <p>Tumor growth remains unaltered but changes the tumor's metabolic state</p> Signup and view all the answers

    What type of diseases are most mitochondrial mutations suggested to cause?

    <p>Complex diseases</p> Signup and view all the answers

    What effect does the removal of mitochondrial DNA (mtDNA) have on cancer cells?

    <p>It leads to reduced tumor formation.</p> Signup and view all the answers

    What characteristic is observed in cells that lack mitochondrial DNA?

    <p>They show slower tumor formation.</p> Signup and view all the answers

    How do metastatic cells restore their tumor-initiating efficiency?

    <p>By acquiring mtDNA from host cells.</p> Signup and view all the answers

    What role do functional mitochondria play in cancer cells?

    <p>They are essential for tumor growth and initiation.</p> Signup and view all the answers

    What is the consequence of removing mtDNA from a cancer cell line?

    <p>It leads to slower tumor formation.</p> Signup and view all the answers

    What publication discusses the acquisition of mtDNA by metastatic cells?

    <p>Cell Metabolism 2015</p> Signup and view all the answers

    What is the approximate ratio of individuals affected by mitochondrial-related diseases?

    <p>1 in 5,000</p> Signup and view all the answers

    What percentage of people carry at least one heteroplasmy according to the 1000G Project?

    <p>90%</p> Signup and view all the answers

    What is the primary challenge in studying mitochondrial diseases?

    <p>Complexity of inheritance and detection</p> Signup and view all the answers

    What is the function of the DddA enzyme mentioned in the context of mitochondrial diseases?

    <p>It catalyzes the conversion of cytosine to uracil</p> Signup and view all the answers

    What is the likelihood of individuals carrying a mutation associated with mitochondrial disease?

    <p>Around 20%</p> Signup and view all the answers

    What method is used to combine mitochondria from a patient and a healthy donor?

    <p>In vitro fertilization</p> Signup and view all the answers

    Heteroplasmies with a presence of more than what percentage have lower predicted effects on mitochondrial function?

    <p>60%</p> Signup and view all the answers

    Which type of genome editing tool is NOT effective on mitochondria?

    <p>Nuclear genome editing tools</p> Signup and view all the answers

    Study Notes

    Mitochondrial DNA Overview

    • Circular DNA structure present in mitochondria, coding for proteins in the oxidative phosphorylation (OXPHOS) chain.
    • Contains 13 polypeptides, 22 transfer RNAs, and 2 ribosomal RNAs.

    Mitochondrial Genome Characteristics

    • Each mitochondrion houses multiple copies of its DNA.
    • Homoplasmy refers to all mitochondrial DNA copies being identical, while heteroplasmy indicates the presence of multiple types or variations of mitochondrial DNA.

    Inheritance of Mitochondrial DNA

    • Mitochondrial DNA is maternally inherited, meaning offspring receive their mitochondrial DNA exclusively from their mother.

    Nuclear vs. Mitochondrial Genomes

    • Nuclear genome encodes essential proteins required for mitochondrial function and maintenance.
    • Proteins from the nuclear genome are involved in the replication, transcription, and repair of mitochondrial DNA.

    Mitochondrial Disorders

    • Disorders can stem from mutations in the nuclear genome affecting mitochondrial function, following Mendelian inheritance patterns.

    • Example: Friedreich Ataxia

      • Incidence of approximately 1 in 30,000, characterized by progressive gait and limb ataxia due to GAA repeat expansion in the FXN gene.

    • Example: Parkinson’s Disease

      • Affects 1-2% of the population; symptoms include rigidity and tremor due to dopaminergic neuron loss.
      • Genes linked to Parkinson's: PINK1 and Parkin, involved in mitochondrial health and autophagy.

    Mutations in Mitochondrial DNA

    • Mitochondrial diseases affect roughly 1 in 5,000 individuals, while a higher proportion carry disease-associated mutations.
    • ~90% of individuals have at least one heteroplasmy, with 20% carrying mutations linked to disease.
    • Heteroplasmies with >60% presence generally exhibit lower impacts on overall mitochondrial function.

    Strategies for Mitochondrial Disease Treatment

    • Using oocytes from healthy donors with normal mitochondria for IVF can circumvent mutations in a patient's mitochondria.
    • New methods using cytidine deaminase enzymes allow for editing of the mitochondrial genome without harmful DNA breaks.

    Mitochondrial Contributions to Common Diseases

    • Mitochondrial variants can influence susceptibility to complex diseases such as diabetes, Alzheimer's, and Parkinson's disease, though most associations remain correlative.
    • Cancer Connection:
      • The "Warburg Effect" describes how tumors rely on aerobic glycolysis, altering glucose metabolism, and potentially linked to mitochondrial dysfunction.
      • Mitochondrial mutations (e.g., Mt-ND3 in breast cancer, Mt-CO1 in prostate cancer) raise questions about their role in tumorigenesis versus mitochondrial function.

    Functional Importance of Mitochondria in Cancer

    • Removal of mitochondrial DNA from cancer cells leads to reduced tumor growth and aggressiveness.
    • Metastatic cells can acquire mtDNA from host cells, enabling tumor initiation efficiency, highlighting the critical role of functional mitochondria in cancer development.

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    Description

    Explore the fascinating world of mitochondrial DNA, which is essential for coding proteins in the oxidative phosphorylation (OXPHOS) chain. This quiz covers important components, including polypeptides, transfer RNAs, and ribosomal RNAs. Test your understanding of the unique characteristics and functions of mitochondrial DNA.

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