Flashcards in Lec 2.2. Mitochondrial Genetics Deck (24)
Mitochondria and chloroplasts contain what?
Mitochondria is the source of what for the cell?
What does Organelle DNA encode for?
Some polypeptides used by the organelle, rRNA and some tRNAs
What is the Endosymbiotic theory of origin of organelles (mitochondria and chloroplasts)?*
That mitochondria and chloroplasts were once free-living bacteria
What is some supporting evidence to this theory?*
Both organelles are similar to eubacteria, and their DNA sequences within them.
What are two unique characteristics from organelle DNA?
Uniparental inheritance of organelle-encoded traits (mostly from mom), replicative segregation.
What does heteroplasmic mean?*
Means that not all mitochondria is the same, dif genetic sequence in mitochondria
Organelles in a heteroplasmic cell segregate how?
Randomly into the progeny cells.
Petite mutations in yeast helped us in what?
Understand mitochondria DNA
What are petite mutations in yeast?
Mutations in mtDNA rendering the cells unable to grow on nonfermentable carbon sources.
Mitochondrial genomes are generally
small and vary greatly
Why do most mitochondrial genes migrate to the nucleus?
Mitochondria cant protect DNA by itself, prone to mutation. Moves to make use of the nucleus repair mechanisms
What can cause looping/pairing in plant mitochondria?
Direct repeats. Which result in variation in DNA size
Why does mtDNA have a high mutation rate?
Cant repair itself
Most copies of mtDNA are
What is the reason for some muscle myopathy?
Faulty mitochondria, resulting in low energy production.
When do most human diseases associated with damaged mtDNA appear?
Middle age or later
Those with mutations in mtDNA start life with decreased or increased oxidative phosphorylation capacity?
When do heteroplasmic mutations reach threshold to cause changes?
There is no clear threshold, however once that threshold is reached, you get that certain phenotype.
What is Leigh syndrome?
Rare genetic neurometabolic disorder that results from mutations causing loss of function of the mitochondria. They reached the threshold, but their mother didnt
What are symptoms to Leigh syndrome?
Appear 3months to 2 years of age. Live to teens.
How could one prevent transmission of mitochondrial DNA disease?
Pronuclear transfer in human embryos.
How does pronuclear transfer work?
Get two eggs, one from mother and donor. Each fertilized with father sperm. Remove the nuclei from the donor egg. Place the nuclei from the mother into the donor egg. Resulting in a child from 3 parents.