Mitochondrial myopathies Flashcards
What features of the mitochondrial genetic system resemble those found in prokaryotes?
Circular DNA and 70S ribosomes.
What strengthened the theory that mitochondria are the evolutionary descendants of a prokaryote?
The result of an endosymbiotic relationship with ancestral eukaryotic cells early in the history of life on earth.
What is the origin of most mitochondria in an embryo?
Most mitochondria in an embryo are derived from the egg.
Where are most mitochondria found in a sperm?
Most mitochondria in a sperm are found in the tail.
What happens to paternal mitochondria that enter the egg during fertilization?
Any paternal mitochondria that enter the egg are destroyed.
What type of inheritance is associated with mitochondria?
Maternal inheritance.
How many copies of the genome are typically found in each mitochondrion?
5-10 copies.
How many mitochondria does a cell typically have?
2-2000 mitochondria.
What is the size of the human mitochondrial genome?
16.5 kilobases (kb).
Where are the majority of mitochondrial proteins encoded?
The majority of mitochondrial proteins are encoded by nuclear DNA on cytosolic ribosomes, imported, and then assembled in the mitochondrion.
What has happened to many of the genes needed for mitochondrial function?
Many of the genes needed for mitochondrial function have moved from the mitochondrion into the nuclear genome.
What does the mitochondrial genome code for?
The mitochondrial genome codes for 13 respiratory chain proteins, 2 rRNA molecules, and 22 tRNA molecules.
How does the mitochondrial genetic code differ from the normal universal genetic code?
The mitochondrial genetic code differs from the normal universal genetic code.
How does the tRNA structure in mitochondria differ from nuclear-encoded tRNA?
The tRNA structure in mitochondria differs from nuclear-encoded tRNA.
What is the major producer of reactive oxygen species (ROS) in the cell?
The respiratory chain.
What happens to mitochondrial DNA (mtDNA) with age?
Defects in mtDNA accumulate with age, and mtDNA mutates more rapidly (10-fold) than nuclear DNA.
Which DNA is more susceptible to damage by reactive oxygen species (ROS)?
Mitochondrial DNA (mtDNA) suffers the greatest exposure to, and damage by, ROS.
Why is mtDNA less effective at correcting mistakes and repairing damage?
mtDNA is less effective at correcting mistakes and repairing mtDNA damage compared to nuclear DNA.
What are the major types of reactive oxygen species (ROS) generated in the mitochondrion?
The major types of ROS generated in the mitochondrion are superoxide anion (O2.-), hydroxyl radical (HO.), peroxide ion (O22-), hydrogen peroxide (H2O2), and hypochlorous acid (HOCl).
What happens to the efficiency of oxidative phosphorylation with age?
The efficiency of oxidative phosphorylation declines with age, partly due to the accumulation of mutations to mtDNA caused by ROS.
Which conditions or diseases are strongly implicated in defects in oxidative phosphorylation?
Defects in oxidative phosphorylation are strongly implicated in Alzheimer’s disease, Parkinson’s disease, and type II diabetes.