Chapter 5: Aerobic Respiration and the Mitochondrion Flashcards
How are the respective types of Mitochondrial structure and function differently from one another?
- Depending on the cell type, mitochondria can have a very different overall structure
- Typical mitochondria are bean-shaped organelles but may be round or threadlike
- Size and number of mitochondria reflect the energy requirements of the cell
What is the function of the Mitochondria?
- They generate ATP
- They are sites of synthesis of numerous substances
- They play a vital role in the uptake and release of calcium ions
- Sites for the regulation events of cell death (apoptosis)
Describe the characteristics and functions of the Mitochondrial Membrane.
- The mitochondrion has two membranes:
1) the outer membrane: serves as its outer boundary
2) the inner membrane: it itself has two major domains- rich in the proteins responsible for the import of mitochondrial proteins
- Cristae: domain lies in the interior of the organelle as a series of invaginated membranous sheets
- houses the machinery needed for aerobic respiration and ATP formation
- Cristae junctions: join of the inner boundary membrane and internal cristae membranes
How are the outer membrane and inner membrane different from one another?
The outer membrane and the inner membrane have different properties:
- the outer membrane: is composed of about 50% lipid by weight and a curious mixture of enzymes; they have porin protein with large internal channels
- the inner membrane: is composed of more than 75% protein by weight; impermeable to even smaller molecules, virtually all molecules and ions require special membrane transporters to gain entrance to the matrix; site for electron transport and ATP synthesis.
Define the characteristics of the Mitochondrial Matrix
- Mitochondria matrix contains:
1) Enzymes
2) Ribosomes
3) several molecules of circular DNA (mtDNA)
- encodes a small number of mitochondrial polypeptides (13 in humans) that are tightly integrated into the inner mitochondrial membrane
What is the study of mitochondrial DNA(mtDNA) used for?
- mtDNA is well suited for use in the study of human migration and evolution
Describe Glycolysis.
- Glycolysis: the first oxidative metabolism step
* located in the cytoplasm
What is the NET reaction of Glycolysis?
Glucose + 2NAD+ + 2ADP + 2Pi —> 2 Pyruvate + 2ATP + 2NADH + 2H+ + 2H2O
Describe Oxidative decarboxylation.
it’s the 2nd oxidative metabolism step
*located in the mitochondrial matrix
What is the NET reaction of Oxidative decarboxylation?
Pyruvate + HS-CoA + NAD+ —> Aceytl CoA + CO2 + NADH + H+
Describe the tricarboxylic acid (TCA) cycle.
the 3rd step of oxidative metabolism step
- Kerbs Cycle
- All enzymes involved are located in the mitochondria matrix (except one)
Describe the Oxidative Phosphorylation in the Formation of ATP.
the 4th step of oxidatve metabolism
- located in the inner mitochondria membrane
What are the three Electron carriers?
- Electron-Transport Complexes (I,II, III, IV)
- Cytochromes (a,b, and c): proteins contain heme groups
- Ubiquinone (UQ): liquid soluble protein
Describe the Electron-Transport Complexes.
- Complex I (NADH dehydrogenase): catalyzes the transfer of electrons from NADH to ubiquinone and transports 4 H+ per pair
- Complex II (succinate dehydrogenase): catalyzes transfer of electrons from succinate to FAD to ubiquinone without transport of H+
- Complex III (cytochrome bc1): catalyzes the transfer of electrons to O2 and transports H+ across the inner membrane
- cytochrome oxidase: a large complex that adds 4 electrons to O2 to form two molecules of H2O
What are the two components of the proton gradient?
- Concentration gradient between matrix and intermembrane space creates a pH gradient (delta pH)
- Separation of charge across the membrane creates an electric potential
