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BF - MM1
Mitochondrial genome and mtDNA disorders
| Question | Answer |
|---|---|
| Mitochondria - what role do they play in apoptosis? | Release cytosolic calcium (by raising membrane permeability) |
| Mitochondria - what is the symbiotic hypothesis? | The theory that mitochondria are the result of endocytosis of aerobic bacteria (explains double membranes) |
| Mitochondria - Is the transcription, translation, and protein synthesis the same as the rest of the cell? | No - it is specific |
| Mitochondria - roughly how many in each cell? | 100's |
| Where are the majority of mitochondrial proteins found? | Mitochondrial genome |
| Mitochondrial genome - type of DNA molecules? | Circular and double stranded |
| Mitochondrial genome - 1700 base pairs, so more/less/the same than the cell nucleus? | Way less |
| Mitochondrial genome - Introns/ no introns? | No introns (93% coding) |
| Mitochondrial genome - replicated dependently/ independently from host cell? | Dependantly |
| Mitochondrial genome - associated proteins? | No |
| Mitochondrial genes - How many? (How many light / heavy?) | 37 - (28H, 9L) |
| Mitochondrial genes - what does it dependent on the nuclear genome for? (3) | Enzymes for replication, transcription, translation and repair (targeted) |
| Mitochondrial genes - Wow many oxidative phosphorylation genes does it code for (out of 83)? | 13 |
| Mitochondrial genes - Which (oxidative phosphorylation) complex does it not code for? | Complex II |
| Mitochondrial genes - What are the remaining genes coding for (that don't code for complexes)? | tRNA's and rRNA's |
| 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 |
| Mitochondrial inheritance is what? | Maternal |
| Which gender is affected by inherited mitochondrial disorders? | Both |
| Mitochondria - What is homoplasy? | A mammalian cell whose copies of mitochondrial DNA are all identical |
| Mitochondria - What is heteroplasmy? | Proportions of mitochondria varying between cells and tissues |
| Reduction of mtDNA during oogenesis - what is the bottleneck efffect? | Reduction in genetic variation |
| Reduction of mtDNA during oogenesis - what is replicative segregation? | Random replication and partitioning of mitochondrial genomes in daughter cells |
| 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 |
| Mutation in mtDNA - What kind of mutations? (3) | Substitutions, deletions, insertions |
| Mutation in mtDNA - What happens with age? | Accumulate |
| Pathogenicity of mtDNA mutations - How many mutations described? | Over 300 |
| Pathogenicity of mtDNA mutations - Are deletions inherited/ sporadic? | Sporadic and not transmitted |
| Pathogenicity of mtDNA mutations - Are point mutations inherited/ sporadic? | Maternal inheritance |
| Pathogenicity of mtDNA mutations - What are they dependent on? | Mutation site |
| Pathogenicity of mtDNA mutations - What transcriptional/ translational structures can be effected? (2) | Polypeptide or RNA |
| Pathogenicity of mtDNA mutations (threshold for bioenergetic 'energy failure')- What % must be mutant for deletions? | 60% |
| Pathogenicity of mtDNA mutations (threshold for bioenergetic 'energy failure')- What % must be mutant for tRNA mutations? | 90% |
| mtDNA disorders - Rare/ common? | Rare (1:10,000) |
| 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 |
| mtDNA disorders - Early/ late onset? | Late (ages 20-30) |
| Clinical features of mtDNA disorders - Muscle? (3) | Progressive external opthalmoplegia + ptosis, myopathy (ragged red fibres) |
| Clinical features of mtDNA disorders - Heart? (2) | Cardiomyopathy, conduction |
| Clinical features of mtDNA disorders - What may irregular heart beat be due to? | Decreased ATP |
| Clinical features of mtDNA disorders - CNS? (3) | Transient hemiparesis ( 1 sided muscle weakness) ataxia, seizures |
| Clinical features of mtDNA disorders - Eye? (1) | Pigmentary retinopathy |
| Clinical features of mtDNA disorders - Ear? | Nerve deafness |
| Clinical features of mtDNA disorders - What is the pathology of 'nerve deafness'? | Damage to auditory nerve |
| Clinical features of mtDNA disorders - Endocrine? (1) | Diabetes |
| Clinical features of mtDNA disorders - Metabolic (1)? | Lactic acidosis |
| Clinical features of mtDNA disorders - What does CPEO stand for? | Chronic Progressive External Opthalmoplegia |
| Clinical features of mtDNA disorders (CPEO) - Most common type of what type of mtDNA disorder? | Oxidative phosphorylation disorder |
| Clinical features of mtDNA disorders (CPEO) - It is usually benign, what are sympotoms? (3) | Fatigue, ptosis, loss of eye movement |
| Clinical features of mtDNA disorders (CPEO) - What is it a result of in the genome? | Single deletion |
| Clinical features of mtDNA disorders (CPEO) - What is Kearns sayre syndrome? | Severe subtype of CPEO |
| Clinical features of mtDNA disorders (CPEO) - Symptoms of Kearns sayre syndrome? | Cardiac, ataxia, retinopathy (poor prognosis) |
| Clinical features of mtDNA disorders (MELAS) - What does MELAS stand for? | Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-like episodes |
| Clinical features of mtDNA disorders (MELAS) - Symptoms of encephalopathy? (3) | Stroke like episodes (hemiparisis), headache and vomitting, seizures |
| Clinical features of mtDNA disorders (MELAS) - Does it present in childhood/ adulthood? | Both |
| Clinical features of mtDNA disorders (MELAS) -What gene is mutated in >85% of cases? | tRNA(leu) |
| Clinical features of mtDNA disorders (LHON) - What does LHON stand for? | Leber's Hereditary Optic Myopathy |
| Clinical features of mtDNA disorders (LHON) - What type of vision loss? | Subacute bilateral |
| Clinical features of mtDNA disorders (LHON) - age of onest? | Mean = 23 years |
| Clinical features of mtDNA disorders (LHON) - Males or females more likely? | Males (by 2-3x) |
| Clinical features of mtDNA disorders (LHON) - What kind of mutation? | Missense mutation in 1 of at least 4 genes |
| Clinical features of mtDNA disorders (LHON) - Which oxidative phosphorylation complex is the mutation in? | Complex I |
| Clinical features of mtDNA disorders (MERRF) - What does MERRF stand for? | Myoclonic epilepsy with ragged red fibres |
| Clinical features of mtDNA disorders (NARP) - What does NARP stand for (also it's sympotms)? | Neurogenic wekaness, Ataxia, Retinitus pigmentosa |
| Clinical features of mtDNA disorders: INVESTIGATION - What is seen in the biochemistry? (1) | Raised lactate |
| Clinical features of mtDNA disorders: INVESTIGATION - What is seen in muscle biopsy? (3) | Ragged red fibres, Cox -ve, succinate dehydrogenase -ve |
| Clinical features of mtDNA disorders: INVESTIGATION - In the DNA in leukocytes what is often observed? (type of mutation) | Point mutations |
| Clinical features of mtDNA disorders: INVESTIGATION -In the DNA in muscle what is often observed? (type of mutation) | Deletions/ insertions |
Created by:
benfenner1
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