Mitochondrial genome and mtDNA disorders
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| Mitochondria - what role do they play in apoptosis? | Release cytosolic calcium (by raising membrane permeability)
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| Mitochondria - what is the symbiotic hypothesis? | The theory that mitochondria are the result of endocytosis of aerobic bacteria (explains double membranes)
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| Mitochondria - Is the transcription, translation, and protein synthesis the same as the rest of the cell? | No - it is specific
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| Mitochondria - roughly how many in each cell? | 100's
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| Where are the majority of mitochondrial proteins found? | Mitochondrial genome
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| Mitochondrial genome - type of DNA molecules? | Circular and double stranded
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| Mitochondrial genome - 1700 base pairs, so more/less/the same than the cell nucleus? | Way less
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| Mitochondrial genome - Introns/ no introns? | No introns (93% coding)
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| Mitochondrial genome - replicated dependently/ independently from host cell? | Dependantly
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| Mitochondrial genome - associated proteins? | No
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| Mitochondrial genes - How many? (How many light / heavy?) | 37 - (28H, 9L)
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| Mitochondrial genes - what does it dependent on the nuclear genome for? (3) | Enzymes for replication, transcription, translation and repair (targeted)
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| Mitochondrial genes - Wow many oxidative phosphorylation genes does it code for (out of 83)? | 13
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| Mitochondrial genes - Which (oxidative phosphorylation) complex does it not code for? | Complex II
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| Mitochondrial genes - What are the remaining genes coding for (that don't code for complexes)? | tRNA's and rRNA's
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| Mitochondrial genes - How is mitochondrial DNA well organised? | tRNA's do double duty. (The spaces between the areas coding for proteins are coding for tRNA's
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| Mitochondrial inheritance is what? | Maternal
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| Which gender is affected by inherited mitochondrial disorders? | Both
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| Mitochondria - What is homoplasy? | A mammalian cell whose copies of mitochondrial DNA are all identical
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| Mitochondria - What is heteroplasmy? | Proportions of mitochondria varying between cells and tissues
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| Reduction of mtDNA during oogenesis - what is the bottleneck efffect? | Reduction in genetic variation
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| Reduction of mtDNA during oogenesis - what is replicative segregation? | Random replication and partitioning of mitochondrial genomes in daughter cells
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| Mutation in mtDNA - What is the high mutation rate due to? (5) | High O2 radicals, no introns, no protective proteins, less efficient replication, no excision repair
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| Mutation in mtDNA - What kind of mutations? (3) | Substitutions, deletions, insertions
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| Mutation in mtDNA - What happens with age? | Accumulate
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| Pathogenicity of mtDNA mutations - How many mutations described? | Over 300
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| Pathogenicity of mtDNA mutations - Are deletions inherited/ sporadic? | Sporadic and not transmitted
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| Pathogenicity of mtDNA mutations - Are point mutations inherited/ sporadic? | Maternal inheritance
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| Pathogenicity of mtDNA mutations - What are they dependent on? | Mutation site
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| Pathogenicity of mtDNA mutations - What transcriptional/ translational structures can be effected? (2) | Polypeptide or RNA
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| Pathogenicity of mtDNA mutations (threshold for bioenergetic 'energy failure')- What % must be mutant for deletions? | 60%
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| Pathogenicity of mtDNA mutations (threshold for bioenergetic 'energy failure')- What % must be mutant for tRNA mutations? | 90%
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| mtDNA disorders - Rare/ common? | Rare (1:10,000)
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| mtDNA disorders - What does 'clinically heterozygous' mean? | Same disease can be caused by a variety of genes/ alleles, therefore individual mutations can cause different diseases
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| mtDNA disorders - Early/ late onset? | Late (ages 20-30)
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| Clinical features of mtDNA disorders - Muscle? (3) | Progressive external opthalmoplegia + ptosis, myopathy (ragged red fibres)
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| Clinical features of mtDNA disorders - Heart? (2) | Cardiomyopathy, conduction
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| Clinical features of mtDNA disorders - What may irregular heart beat be due to? | Decreased ATP
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| Clinical features of mtDNA disorders - CNS? (3) | Transient hemiparesis ( 1 sided muscle weakness) ataxia, seizures
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| Clinical features of mtDNA disorders - Eye? (1) | Pigmentary retinopathy
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| Clinical features of mtDNA disorders - Ear? | Nerve deafness
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| Clinical features of mtDNA disorders - What is the pathology of 'nerve deafness'? | Damage to auditory nerve
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| Clinical features of mtDNA disorders - Endocrine? (1) | Diabetes
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| Clinical features of mtDNA disorders - Metabolic (1)? | Lactic acidosis
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| Clinical features of mtDNA disorders - What does CPEO stand for? | Chronic Progressive External Opthalmoplegia
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| Clinical features of mtDNA disorders (CPEO) - Most common type of what type of mtDNA disorder? | Oxidative phosphorylation disorder
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| Clinical features of mtDNA disorders (CPEO) - It is usually benign, what are sympotoms? (3) | Fatigue, ptosis, loss of eye movement
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| Clinical features of mtDNA disorders (CPEO) - What is it a result of in the genome? | Single deletion
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| Clinical features of mtDNA disorders (CPEO) - What is Kearns sayre syndrome? | Severe subtype of CPEO
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| Clinical features of mtDNA disorders (CPEO) - Symptoms of Kearns sayre syndrome? | Cardiac, ataxia, retinopathy (poor prognosis)
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| Clinical features of mtDNA disorders (MELAS) - What does MELAS stand for? | Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-like episodes
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| Clinical features of mtDNA disorders (MELAS) - Symptoms of encephalopathy? (3) | Stroke like episodes (hemiparisis), headache and vomitting, seizures
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| Clinical features of mtDNA disorders (MELAS) - Does it present in childhood/ adulthood? | Both
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| Clinical features of mtDNA disorders (MELAS) -What gene is mutated in >85% of cases? | tRNA(leu)
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| Clinical features of mtDNA disorders (LHON) - What does LHON stand for? | Leber's Hereditary Optic Myopathy
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| Clinical features of mtDNA disorders (LHON) - What type of vision loss? | Subacute bilateral
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| Clinical features of mtDNA disorders (LHON) - age of onest? | Mean = 23 years
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| Clinical features of mtDNA disorders (LHON) - Males or females more likely? | Males (by 2-3x)
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| Clinical features of mtDNA disorders (LHON) - What kind of mutation? | Missense mutation in 1 of at least 4 genes
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| Clinical features of mtDNA disorders (LHON) - Which oxidative phosphorylation complex is the mutation in? | Complex I
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| Clinical features of mtDNA disorders (MERRF) - What does MERRF stand for? | Myoclonic epilepsy with ragged red fibres
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| Clinical features of mtDNA disorders (NARP) - What does NARP stand for (also it's sympotms)? | Neurogenic wekaness, Ataxia, Retinitus pigmentosa
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| Clinical features of mtDNA disorders: INVESTIGATION - What is seen in the biochemistry? (1) | Raised lactate
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| Clinical features of mtDNA disorders: INVESTIGATION - What is seen in muscle biopsy? (3) | Ragged red fibres, Cox -ve, succinate dehydrogenase -ve
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| Clinical features of mtDNA disorders: INVESTIGATION - In the DNA in leukocytes what is often observed? (type of mutation) | Point mutations
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| Clinical features of mtDNA disorders: INVESTIGATION -In the DNA in muscle what is often observed? (type of mutation) | Deletions/ insertions
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