Mitochondria Flashcards
What size is a mitochondria?
1-10um
What are the functions of the mitochondria?
-Cell signalling
-Cell differentiation
-Cell death
-Control of cell cycle and growth
What is needed to neutralise a molecule of ATP?
2 molecules of magnesium
Where is mitochondria localised?
-Aerobic eukaryotic cells
Where do mitochondria cluster in the body?
-Regions of greatest metabolic activity, e.g. greatest muscle groups
What is the name of the theory of how mitochondria arise?
Endosymbiotic theory
What does the endosymbiotic theory state?
Mitochondria are descended from ancient bacteria, which were engulfed by the ancestors of eukaryotic cells
How many types of mitochondrial proteins do humans have?
614
When do mitochondrial proteins increase in numbers?
At times when more energy is needed
What is the role of the outer membrane of the mitochondria?
Encloses the organelle
What is the protein to phospholipid ratio in the outer membrane of the mitochondria?
1:1
What is the name of the large proteins in the outer membrane?
Porins
What is the role of porins in the outer membrane?
Controls the size of proteins that can pass through the membrane
How can larger proteins enter the outer membrane of the mitochondria?
They have a signalling sequence to utilise active transport called a translocase
What can disruption of the outer membrane of the mitochondria lead to?
Proteins leak into the cytosol and larger molecules enter leading to cell death
What is the intermembrane space of the mitochondria?
Space between the outer membrane and inner membrane
What is the name of the protein that is located in the intermembrane space?
Cytochrome c
What are the functions of proteins in the mitochondria?
-Redox reactions of oxidative phosphorylation
-ATP synthase
-Transport proteins
Where does ATP synthesis occur?
Matrix
What is the role of transport proteins?
Regulates metabolite passage in and out of the matrix
What is ATP synthase?
The enzyme that synthesises ATP from ADP and phosphate group
What does the inner membrane consist of?
A high protein-to-phospholipid ratio, 3:1
What phospholipid is the inner membrane rich in?
Cardiolipin
What is unusual about cardiolipin
has 4 fatty acids rather than 2, helps make membrane impermeable
What is the cristae of the mitochondria?
Invaginations of the inner membrane
What is the role of the cristae?
Increases surface area of inner membrane
What does an increased surface area of the inner membrane aid?
ATP production
What is the new theory for the shape of mitochondria organelles?
Extensively branched
-Fewer
-Larger size
What is the mitochondrial matrix?
The space enclosed within the inner membrane
What is contained in the matrix?
-2/3 of proteins
-Enzymes
-Mitochondrial ribosomes
-tRNA
What are the functions of the enzymes in the matrix?
-Oxidation of pyruvate and fatty acids
-Krebs cycle
What metabolic functions occur in the outer membrane?
-Phospholipid synthesis
-Fatty acid desaturation
-Fatty acid elongation
What metabolic functions occur in the inner membrane?
-Electron transport
-Oxidative phosphorylation
-Pyruvate import
-Fatty acyl CoA import
-Metabolite transport
What metabolic functions occur in the matrix?
-Pyruvate oxidation
-TCA cycle
-DNA replication
-RNA synthesis
-Protein synthesis
What is the role of mitochondrial DNA?
Codes for most proteins
genes for RNA, tRNA and protein coding regions
What are mitochondrial diseases?
Genetic defects of muscle or nerve tissue
What are the results of severe mitochondrial diseases?
-Infant death
-Blindness
-Deafness
-Seizures
What are the results of milder mitochondrial diseases?
-Muscle weakness
-Intolerance to exercise
-Infertility
Where do most defects in mitochondrial DNA occur?
In genes coding for mitochondrial tRNA
How do mitochondrial diseases arise?
When most of mitochondria in a tissue have a certain mutant gene
