Mitochondrial Genetics

Question 1

Mitonuclear match

Answer 1

Nuclear genes involved in the ETC experience similar rates of mutation and evolution when compared to the mitochondrial genes b/c they must co-evolve in order to maximize efficiency of metabolism

Question 2

Why are mitochondrial genes especially susceptible to mutations?

Answer 2

b/c respiration and oxidative phosphorylation in mitochondria produce substantial amounts of reactive oxygen species , which can damage DNA

Question 3

% of total cell volume taken up by mitochondria vs nucleus?

Answer 3

nucleus- 54%

mito- 22%

Question 4

Endosymbiotic hypothesis

Answer 4

Origin of eukaryotic cells

Ancestral mitochondrial genome in prokaryotic cell engulfed by cell with nuclear genome –> just ended up becoming mitochondria

Question 5

nuclear proteins –> mitochondria pathway

Answer 5

genomic dna –> RNA –> cytosol –> precursor protein –> mitochondria –> imported protein –> synthesized

Question 6

ROS

Answer 6

reactive oxygen species
causes cellular damage and aging
a leak will uncouple chemiosmotic energy transfer

Question 7

mitochondrial genome- tRNA

Answer 7

makes their own tRNA - specific sequences of the genome

mutations cause a broad spectrum of clinical manifestations

Question 8

MELAS

Answer 8

pathological mutations in tRNA

Question 9

Heteroplasmic inheritance

Answer 9

the fraction of mitochondria that are mutant in any given cell can vary tremendously

some tissue with a threshold % of mutant mitochondria will display a mutant phenotype while others will appear phenotypically normal

*due to the fact that mitochondria inherited with the cytoplasm

Question 10

Maternal transmission of mitochondrial disorders

Answer 10

1) All offspring of an affected or carrier female are at risk of being affected
2) All daughters of an affected or carrier female are at risk of transmitting the disease
3) Affected males cannot pass the condition to any of their children