WEEK 13: Mitochondrial DNA and Inheritance Flashcards
(10 cards)
Describe what mitochondrial DNA (mtDNA) is
each mitochondrion has multiple copies of mtDNA
it is double-stranded circular and unbound; reminiscent of the DNA in bacterial cells.
How are mitochondria inherited?
it is not inherited via sperm, sperm have many mitochondria to power motility but only the sperm nuclear DNA enters the egg.
What are mitochondrial diseases?
conditions caused by the dysfunction of mitochondria, which affects tissues that have a high energy demands, like the CNS, heart and muscle
Does the mother or father pass on mitochondrial diseases to their offspring?
due to the maternal inheritance character of mitchondrial diseases, males won’t pass on mitochondrial diseases to their offspring
What is heteroplasmy?
It describes when cells have multiple types of mitochondria (normal & mutated mtDNA)
What causes different proportions of normal and mutant mitochondria?
random separation of the mitochondria into 2 daughter cells during cell division
What does heteroplasmy result in, and what does it give rise to
highly variabe expressivity: severity of the disease can be different between individuals depending on differing proportions of mtDNA mutation
low penetrance: some individuals don’t show the disease due to low proportion of mtDNA
mtDNA only comes from the?
ovum
How do some diseases affecting mitochondrial function do not show mitochondrial inheritance?
this is because most genes required for mitochondrial function are located in the nuclear genome
mutation in those nuclear genes still affect mitochondrial function but could be inherited from mother or father
over evolution most mitochondrial genes are transferred to our chromosomes and are still essential even though they’re not mtDNA
Give an example of a mitochondrial inherited disease
maternally-inherited leber hereditary optic atrophy
