Structure and function
What separates the cytosol from the mitochondrial matrix?
The outer and inner mitochondrial membranes.
What type of DNA is found in mitochondria?
Circular double-stranded DNA (mtDNA).
Where are most mitochondrial proteins encoded?
In the nuclear genome.
What process occurs on the inner mitochondrial membrane?
Oxidative phosphorylation (OXPHOS).
What is a primary mitochondrial disease (PMD)?A disease caused by mutations in mtDNA or nuclear genes encoding mitochondrial proteins.
A disease caused by mutations in mtDNA or nuclear genes encoding mitochondrial proteins.
What are the folded structures of the inner membrane called?
Cristae
How many genes are encoded by human mtDNA?
37 genes
What does TOM stand for?
Translocase of the Outer Membrane.
What are the five complexes of the electron transport chain collectively responsible for?
Generating a proton gradient and producing ATP.
What is a secondary mitochondrial disease (SMD)?
A disorder where mitochondrial function is indirectly impaired.
What is contained within the mitochondrial matrix?
mtDNA, mitochondrial ribosomes, and enzymes for the TCA cycle.
Are mitochondria inherited? If yes, how?
Yes; Maternally, through the oocyte.
What molecule drives ATP synthesis?
The proton gradient across the inner membrane.
What does MELAS stand for?
Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes.
What is the role of cristae in mitochondrial function?
They increase the surface area for oxidative phosphorylation.
Define heteroplasmy.
Presence of both normal and mutated mtDNA in a tissue.
What does Complex V do?
ATP synthase converts ADP and Pi into ATP using the proton gradient.
What is the purpose of mitochondrial replacement therapy (MRT)?
To prevent transmission of defective maternal mitochondria by using donor mitochondria.
Explain how the double-membrane structure supports ATP production.
It allows separation of the intermembrane space and matrix, enabling a proton gradient essential for ATP synthesis.
How does heteroplasmy influence disease severity?
The proportion of mutant to wild-type mtDNA affects how severely tissues are impacted.
What does the SAM complex do?
It assembles β-barrel proteins into the outer mitochondrial membrane.
Describe how the electron transport chain and ATP synthase are functionally linked.
The ETC establishes a proton gradient that ATP synthase uses to drive ATP formation (chemiosmotic mechanism)
What research technique can identify mitochondrial proteins on a large scale?
Mass spectrometry-based proteomics.