Mitochondria Flashcards
How many genes does the mitochondria contain?
37 genes, 13 of which encode subunits of the respiratory chain complexes
Nuclear genes encode most of the mitochondrial proteins.
How are mitochondrial genes inherited?
Maternally
How many membranes do mitochondria have?
2 membranes - Outer,(OMM) very permeable. Inner,(IMM) impermeable.
What does the IMM contain?
Highly convoluted with invaginations - cristae containing multiple copies of respiratory chain and ATP synthase.
There are multiple transporter proteins in the IMM, give an example?
Carnitine.
What does the matrix of the mitochondria contain.
Many catabolic enzyme systems:List on diagram (examples: DNA, ribosomes, ions, metabolites , citric acid cycle, beta oxidation, pyruvate dehydrogenase and for amino acid oxidation.
How are mitochondria highly dynamic? Why is this done?
They are constantly dividing by fission - to get rid of damaged mitochondria.
When does a lot of fission happen?
During anabolism
What is it called when mitochondria come together?
fusion
What is it called when mitochondria are being degraded when damaged or non-functional?
Mitophagy, proteins are also degraded by this.
What can differ between mitochondria cell types?
The cell need for high energy demand etc.
Number of cristae can change depending on the metabolic need.
What type of mutations in genes encoding for mitochondrial proteins can cause disease?
Inherited optic neuropathies.
- degeneration of retinal cells (loss of vision)
What causes Inherited optic neuropathies?
Missense mutation in mitochondria genes encoding subunits of complex 1.
Maternal (primarily)and nuclear inherited.
What is Leigh disease?
This is a neurological and psychomotor dysfunction - due to mutations in both mitochondrial and nuclear genes that encodes for protein complexes of mt chain complex IV
What is MELAS?
Mitochondrial encephalopathy with lactic acidosis and stroke like episdoes.
What is MERFF?
Myoclonic epilepsy with red ragged fibres.
MELAS is the most common cause of?
Mutations in mitochondrial gene encoding tRNA necessary for synthesis of mitochondrial proteins and this is also cause of MERFF
What do diseases MERFF and MELAS have?
Defective mitochondrial protein synthesis.
What is visible in the mitochondria of MERFF patients?
Skeletal muscle has abnormal shaped mitochondria with crystalline deposits.
When was the first mitochondrial transplant ?
In 2015 UK approval of embryonic mitochondrial transfer to treat chronic maternally inherited mitochondrial diseases (3 person baby)
What does the mitochondrial transplant consist of?
- chromosomes removed from mutated m mother
- put into healthy donor egg
- egg fertilised
- normal embryo develops, mother chromosome, male chromosome, donor mitochondria.
What are ROS?
These are produced by mitochondria - reactive oxygen species.
Which levels of ROS can be beneficial?
Low levels of ROS can be beneficial and cleared by effective antioxidant responses.
What can happen if the electron transport is not correctly coupled to ATP production and O2 consumption?
ROS can be over produced.
