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Questions and Answers
Which statement is NOT true regarding Leber disease?
Which statement is NOT true regarding Leber disease?
Which of the following is NOT a key factor contributing to the involvement of mitochondria in disease pathogenesis?
Which of the following is NOT a key factor contributing to the involvement of mitochondria in disease pathogenesis?
Which of the following is the main difference between Leber disease and MELAS syndrome, according to the provided content?
Which of the following is the main difference between Leber disease and MELAS syndrome, according to the provided content?
Based on the information provided, which of the following statements is NOT accurate regarding the central dogma of molecular biology (CDMB)?
Based on the information provided, which of the following statements is NOT accurate regarding the central dogma of molecular biology (CDMB)?
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Which of the following is NOT mentioned in the provided information as a consequence of mitochondrial dysfunction?
Which of the following is NOT mentioned in the provided information as a consequence of mitochondrial dysfunction?
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What is the primary reason why mitochondrial diseases affect muscles and the brain the most?
What is the primary reason why mitochondrial diseases affect muscles and the brain the most?
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Which of the following is NOT a characteristic of mitochondrial diseases?
Which of the following is NOT a characteristic of mitochondrial diseases?
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What makes the diagnosis of mitochondrial diseases challenging and complex?
What makes the diagnosis of mitochondrial diseases challenging and complex?
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What is heteroplasmy in the context of mitochondrial diseases?
What is heteroplasmy in the context of mitochondrial diseases?
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Flashcards
Mitochondrial genetic diseases
Mitochondrial genetic diseases
Diseases caused by mutations in mitochondrial proteins affecting ATP production.
Mitochondrial DNA
Mitochondrial DNA
DNA located in mitochondria, inherited only from the mother.
Mitochondrial cytopathies
Mitochondrial cytopathies
Diseases manifesting at birth or childhood due to mitochondrial dysfunction.
Mitochondrial encephalomyopathies
Mitochondrial encephalomyopathies
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Heteroplasmy
Heteroplasmy
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Leber's Hereditary Optic Neuropathy (LHON)
Leber's Hereditary Optic Neuropathy (LHON)
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MELAS syndrome
MELAS syndrome
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Role of mitochondria in diseases
Role of mitochondria in diseases
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Reactive Oxygen Species (ROS)
Reactive Oxygen Species (ROS)
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Central Dogma of Molecular Biology
Central Dogma of Molecular Biology
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Study Notes
Mitochondrial Diseases
- Two categories of mitochondrial pathologies: mitochondrial genetic diseases and other pathological processes.
- Mitochondrial genetic diseases result from mutations in mitochondrial proteins (like respiratory chain complexes) or nuclear genes.
- These mitochondrial diseases often cause enlarged mitochondria inefficient in ATP production, affecting muscles (e.g., ptosis) and brain (frequent seizures).
- Mitochondrial diseases can manifest at any age (infant to adulthood) and can impact other organs (liver, glands, kidneys) .
- Diagnostic methods include plasma component analysis, muscle mitochondrial studies, and mitochondrial DNA sequencing.
- Mitochondrial inheritance is maternal; genetic mutations are not equally distributed in all mitochondrial copies (heteroplasmy).
- Leber's Hereditary Optic Neuropathy (LHON) is a mitochondrial disease caused by mtDNA mutations in complex I, resulting in optic nerve atrophy and potential blindness.
- Exposure to carbon monoxide might trigger LHON.
- MELAS syndrome is caused by mitochondrial DNA mutations, featuring mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes.
Other Pathological Processes Involving Mitochondria
- Mitochondria are involved in all diseases due to their crucial role in cellular energy production.
- Mitochondrial DNA is exposed in the matrix, making it susceptible to damage by reactive oxygen species (ROS), especially free radicals and singlet oxygen.
- Damage from ROS can harm mitochondrial DNA and proteins.
- ROS is linked to major diseases like cardiovascular issues, neurodegenerative conditions, cancer, and diabetes.
- Mitochondrial involvement in apoptosis (programmed cell death) has been demonstrated.
Central Dogma of Molecular Biology
- The central dogma of molecular biology describes genetic information flow from DNA to RNA to protein.
- DNA replication makes identical copies of DNA.
- Transcription converts DNA to RNA.
- Translation converts RNA to proteins.
- This is fundamental in both prokaryotes and eukaryotes, differing in the location primarily.
Genetic Material
- Eukaryotic genetic material is comprised of linear DNA molecules in chromosomes and circular DNA molecules in organelles like mitochondria and chloroplasts.
- The genome is the total number of genes.
- Coding DNA translates into proteins; non coding makes up the majority and includes other regulatory elements, tRNA, rRNA, introns, mobile genetic elements.
- Prokaryotes have a circular chromosome with numerous essential genes and smaller plasmids, crucial for survival in diverse circumstances.
- Plasmids play a critical role in recombinant DNA technology, allowing for gene insertion and manipulation.
DNA Replication
- DNA replication is the process of producing two identical copies of a DNA molecule.
- DNA replication is semi-conservative, meaning each new double helix contains one original strand and one new strand.
- DNA polymerases are enzymes vital in DNA replication.
- Replication forks are formed with leading and lagging strands.
- Okazaki fragments are created on the lagging strands because synthesis proceeds 5' to 3', and DNA polymerases can only synthesize in that direction.
- Eukaryotic replication is slower due to multiple origins of replication per chromosome compared to prokaryotes' single origin.
Medical Implications of DNA Replication Errors
- Mutations are changes in DNA sequence and can result in diseases.
- Point mutations involve a single nucleotide substitution; larger mutations include deletions or insertions.
- Several factors can cause mutations including deamination, depurination and chemical/physical mutagens (alkaline agents, intercalating drugs).
- Understanding mutations guides approaches for disease detection, diagnosis, and treatment (particularly cancer).
- Cellular mechanisms for repairing these mistakes are vital to the health of the organism.
Transcription
- Transcription is the process where genetic information is transcribed from DNA to RNA.
- RNA polymerase enzymes carry out the transcription process.
- mRNA (messenger RNA) is the primary RNA transcript involved in protein synthesis.
- Eukaryotic transcription is complex, involving several RNA polymerases.
- Introns and exons are important features of eukaryotic gene structure. Introns are non-coding regions and are removed from the pre-mRNA during splicing.
- RNA splicing is critical for producing mature mRNA from the primary RNA transcript, which is unique to eukaryotic mRNA.
Translation
- Translation is the process where ribosomes use the genetic information in mRNA to assemble proteins.
- Ribosomes are cellular structures essential for translation.
- The genetic code determines the amino acid sequence of proteins.
- The translation process is vital as proteins carry out diverse functions in all organisms.
- This process can be inhibited by various chemical agents (e.g., antibiotics).
Ribosomes
- Ribosomes are the protein factories of the cell.
- Eukaryotic ribosomes (80S) are distinct from prokaryotic (70S) ribosomes (differents sedimentation coefficients).
- Ribosomes involve multiple rRNA and protein molecules for structure and function.
- They play a role in translation using mRNA as a template to build proteins.
Viral Genetic Material
- Viruses can use DNA or RNA as genetic material.
- Some viruses utilize reverse transcription to synthesize DNA from RNA.
- Viral genetic material can be linear or circular and varies significantly in size.
- Some oncornaviruses have RNA which can, under certain circumstances, transcribe from RNA to DNA.
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Description
Explore the complexities of mitochondrial diseases, including their genetic basis and effects on various organs. This quiz covers diagnostic methods, inheritance patterns, and specific conditions such as Leber's Hereditary Optic Neuropathy. Test your knowledge on this critical aspect of human health.
