Lecture 1: Mitochondria - Exam 5 Flashcards
What experiment was done to study a mutation that affects the mitochondria?
Rat fibroblasts were infected with a Rous sarcoma virus (RSV) strain carrying a temperature sensitive mutation in the src gene. Cells were stained with a mitochondrion-specific fluorescent dye (rhodamine 123) at a nonpermissive temperature (which renders the src gene product inactive). Then shifted to a permissive temperature (which the src gene product is active). The cells were imaged with a fluorescence microscope.
What is the main role of the mitochondria?
Synthesis of ATP.
Describe the transport of metabolites across the mitochondrial inner membrane.
The transport of small molecules across the inner membrane of the mitochondria is mediated by membrane-spanning proteins and driven by an electrochemical gradient.
Give an example of how the electrochemical gradient is created in order for metabolites to be transported across the mitochondrial inner membrane.
For example, 1 ATP charge (-4 charge) is exported from mitochondria to the intermembrane space and then the cytosol by a transporter that exchanges it for 1 ADP (-3 charge).
In contrast, the transport of phosphate (Pi) and pyruvate is coupled to an exchange for hydroxyl ions (OH-).
The high pH in the matrix of the mitochondria corresponds to? What does this favor, and what is it coupled to?
The high pH in matrix corresponds to more hydroxyl ions, favoring their translocation to the intermembrane space. This is coupled to the transport of Pi and pyruvate into the matrix.
How many ATP is produced from glycolysis? How about Citric acid cycle? Electron Transport Chain? How many overall from cellular respiration?
Glycolysis: 2 ATP & 2 pyruvate
Citric acid cycle: 2 ATP
ETC: 32 ATP
Overall: 36 ATP
How is Acetyl-CoA formed?
It is formed from pyruvate by a multienzyme called pyruvate dehydrogenase.
In regards to NADH and FADH2, which one undergoes oxidation and which one undergoes reduction?
NADH: Reduction
FADH2: Oxidation
Reduction rxn: NAD + H+ +2e- -> NADH
Oxidation rxn: FAD + 2H+ + 2e- -> FADH2
Which processes occur in the mitochondrion and which one does not?
Krebs cycle and ETC in mitochondrion and Glycolysis occurs in the cytoplasm of the cell.
ATP Synthesis, The ETC:
Most of the usable energy obtained by the breakdown of carbohydrates and fats is derived from?
The transport of electrons.
The electrons from ___ NADH and ___ FADH2 molecules generated from _______ and the _________ transfer their electrons to molecular oxygen = ?
10 ; 2 ; glycolysis ; Krebs cycle ; a total of 32 ATP molecules
Describe the electron transport chain in mitochondria.
-NADH is produced by glycolysis in the cytosol and the Krebs cycle in the matrix; electrons from NADH enter the ETC at complex I.
-Electrons are transferred to complex III by Coenzyme Q (Ubiquinone).
-Cytochrome c then carries electrons to complex IV (AKA cytochrome oxidase), where they are transferred to O2.
-As electrons are transferred between the redox centers of complex I - IV, protons are translocated from the matrix to the intermembrane space, establishing a proton gradient across the mitochondrial membrane.
-ATP is generated as protons move with the concentration gradient through complex V, which is ATP Synthase*
Describe Complex II (Succinate-Coenzyme Q oxidoreductase) in the ETC.
Complex II (AKA succinate dehydrogenase) consists of 4 proteins and receives electrons from FADH2. Complex II does not pump electrons because doesn’t the free energy.
Complexes I and II, despite their name, do not do what?
They do not operate in series, but both accomplish the same results: the transfer of electrons to Co-enzyme Q
What are the consequences of impaired protein degradation?
Vacuolation (paraptosis), protein aggregates, damaged organelles, impairment of cellular processes, and cell death.
