Mitochondria Flashcards
What are the main functions of mitochondria?
Involved in:
* Cell signaling
* Cell differentiation
* Cell death
* Control of the cell cycle and cell growth
These functions highlight the essential roles of mitochondria in cellular processes.
Where are mitochondria localized in the cell?
In all aerobic eukaryotic cells, clustered in regions of greatest metabolic activity
This localization reflects the mitochondria’s role in energy production.
What theory explains the origin of mitochondria?
Endosymbiotic theory
This theory suggests that mitochondria are descended from ancient bacteria engulfed by eukaryotic ancestors.
What evidence supports the endosymbiotic theory?
Mitochondria contain ribosomes and their own independent genome
The similarity of mitochondrial genome to bacterial genomes supports this theory.
What is the outer membrane of mitochondria characterized by?
Encloses the entire organelle with a protein-to-phospholipid ratio similar to the plasma membrane
The outer membrane contains porins that regulate the passage of small molecules.
What is the function of porins in the outer membrane?
Control the size of molecules that can pass through
Molecules smaller than 5000 Daltons can pass through, while larger molecules cannot.
What is the intermembrane space?
Space between the outer membrane and the inner membrane with a different protein composition than the cytosol
This space contains cytochrome c, which is important for ATP production.
What are the four types of proteins found in the inner membrane of mitochondria?
- Proteins for redox reactions of oxidative phosphorylation
- ATP synthase
- Specific transport proteins
- Protein import machinery
These proteins are crucial for ATP production and metabolite transport.
What is ATP synthase?
An enzyme that synthesizes ATP from ADP and inorganic phosphate (Pi)
ATP synthesis requires energy and involves the movement of protons (H+) across the membrane.
What is the ratio of proteins to phospholipids in the inner membrane?
3 to 1
This high ratio helps maintain the impermeability of the inner membrane.
What are cristae?
Invaginations of the inner membrane that expand the cell surface area
Cristae increase the mitochondria’s ability to produce ATP.
What is the matrix of the mitochondria?
Inner portion containing enzymes and ribosomes for protein synthesis
The matrix is involved in the oxidation of pyruvate and fatty acids and the Krebs cycle.
What is mitochondrial DNA characterized by?
Circular DNA with multiple copies and 37 genes
It codes for proteins essential for mitochondrial function, including 13 protein-encoding regions.
What are mitochondrial diseases associated with?
Symptoms such as death, blindness, deafness, seizures, strokes, or muscle weakness
These diseases often stem from issues with mitochondrial DNA or tRNA.
From whom do we inherit our mitochondrial DNA?
From our mother
The genetic material from the father is degraded in the egg, preserving only maternal mitochondria.
What is the significance of mitochondrial proteins in different species?
Humans have 615 mitochondrial proteins, while mice have 940
This difference reflects the varying energy demands of different species.
What happens to mitochondrial numbers during digestion?
Mitochondrial numbers will increase
This increase is part of the dynamic regulation of the mitochondrial proteome.
What are the three things that can pass through the porins to make ATP?
Iron, Water and Phosphate
What regulates larger proteins passing through?
Translocase
What does things leaking in to the mitochondria mean?
Can mean death for the organelle and cell, death of the organelle can help discover if someone was poisoned.
