Week 5: Mitochondria Flashcards
What is the structure of mitochondrial DNA (mtDNA)?
Circular, 16.6 kb, no introns
Mitochondrial DNA is distinct from nuclear DNA in its structure and organization.
How many genes does mitochondrial DNA (mtDNA) code for?
37 genes:
* 22 tRNAs
* 2 rRNAs
* 13 proteins (MRC subunits)
MRC subunits refer to the proteins that are part of the mitochondrial respiratory chain.
What type of inheritance is associated with mitochondrial DNA (mtDNA)?
Maternally inherited
This means that mtDNA is passed down from mother to offspring.
Is mitochondrial DNA (mtDNA) synchronized with cell division?
No
Mitochondrial DNA replication is independent of the cell cycle.
What is homoplasmy in the context of mitochondrial DNA?
Identical mtDNA
Homoplasmy indicates that all mtDNA in a cell is the same.
What is heteroplasmy in the context of mitochondrial DNA?
Mix of mutant and wild-type mtDNA
Heteroplasmy can lead to a variety of mitochondrial disorders.
True or False: Mitochondrial DNA contains introns.
False
Mitochondrial DNA is unique in that it lacks introns.
What is the process through which ATP is synthesized?
Oxidative Phosphorylation (OXPHOS)
OXPHOS is a key metabolic pathway that generates ATP using energy derived from the electron transport chain.
What is the first key step in ATP synthesis during OXPHOS?
Electron Transport Chain (ETC)
The ETC involves the transfer of electrons from NADH to various proteins in the inner mitochondrial membrane.
What does NADH donate to the Electron Transport Chain?
Electrons
NADH is generated in the Krebs cycle and serves as a crucial electron donor in the ETC.
What does the Electron Transport Chain create across the inner membrane?
Proton gradient
This gradient is essential for driving ATP synthesis via ATP synthase.
Name one proton pump involved in the Electron Transport Chain.
NADH-ubiquinone oxidoreductase
Other proton pumps include Succinate dehydrogenase, Ubiquinone-cytochrome c oxidoreductase, and Cytochrome c oxidase.
What drives ATP synthase in chemiosmotic coupling?
Proton-motive force
The proton-motive force is generated by the proton gradient created during the ETC.
What does ATP synthase convert ADP to?
ATP
ATP synthase is an enzyme that synthesizes ATP from ADP and inorganic phosphate using the energy from the proton gradient.
Fill in the blank: The input for the reaction involving ATP synthesis includes _______.
Acetyl CoA + O2 + ADP
This reaction also produces CO2 and H2O as byproducts.
True or False: The output of the ATP synthesis reaction includes CO2 and H2O.
True
These are the byproducts of the reaction where Acetyl CoA, O2, and ADP are converted into ATP.
What is the primary function of mitochondria?
Producing ATP through aerobic metabolism
Mitochondria are often referred to as the power plants of the cell.
Describe the structure of mitochondria.
Double membrane (outer and inner), inner membrane forms cristae, contains matrix and intermembrane space
The cristae increase the surface area for ATP production.
What is the dynamic nature of mitochondria?
Undergoes fission and fusion, functions as a network interacting with other organelles
This dynamic behavior allows mitochondria to adapt to the cell’s energy needs.
Fill in the blank: Mitochondria are known as the _______ of the cell.
power plants
True or False: Mitochondria have a single membrane structure.
False
Mitochondria have a double membrane structure.
What structures increase the surface area of the inner mitochondrial membrane?
Cristae
Cristae are folds of the inner membrane that enhance ATP production.
What are the two distinct spaces within the mitochondria?
Matrix and intermembrane space
The matrix contains enzymes for the Krebs cycle, while the intermembrane space is involved in the electron transport chain.
What is apoptosis?
Programmed cell death triggered by the release of cytochrome c from mitochondria
Apoptosis involves a caspase cascade leading to cell death.
What is necrosis?
Inflammatory cell death
Necrosis is often caused by injury or disease.
Who won the Nobel Prize in 1978 and for what contribution?
Peter Mitchell for the chemiosmotic theory
The chemiosmotic theory explains how ATP is generated in mitochondria.
What is the size range of mitochondria?
1-2 um
Mitochondria are typically found in large numbers within cells.
How many mitochondria can be found per cell?
10-100,000 per cell
Mitochondria occupy approximately 25% of the cytoplasm.
What is the composition of the outer mitochondrial membrane?
50% lipid/protein, permeable to molecules <10 kDa
This allows small molecules to pass through easily.
What is the composition of the inner mitochondrial membrane?
20% lipid/80% protein, houses respiratory proteins
The inner membrane is critical for ATP synthesis.
Fill in the blank: Mitochondria release _______ to trigger apoptosis.
cytochrome c
This release initiates the caspase cascade.
True or False: Necrosis is a form of programmed cell death.
False
Necrosis is characterized as inflammatory cell death.
