Lecture 1: Mitochondria - Exam 5 Flashcards

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1
Q

What experiment was done to study a mutation that affects the mitochondria?

A

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.

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2
Q

What is the main role of the mitochondria?

A

Synthesis of ATP.

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3
Q

Describe the transport of metabolites across the mitochondrial inner membrane.

A

The transport of small molecules across the inner membrane of the mitochondria is mediated by membrane-spanning proteins and driven by an electrochemical gradient.

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4
Q

Give an example of how the electrochemical gradient is created in order for metabolites to be transported across the mitochondrial inner membrane.

A

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-).

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5
Q

The high pH in the matrix of the mitochondria corresponds to? What does this favor, and what is it coupled to?

A

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.

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6
Q

How many ATP is produced from glycolysis? How about Citric acid cycle? Electron Transport Chain? How many overall from cellular respiration?

A

Glycolysis: 2 ATP & 2 pyruvate
Citric acid cycle: 2 ATP
ETC: 32 ATP
Overall: 36 ATP

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7
Q

How is Acetyl-CoA formed?

A

It is formed from pyruvate by a multienzyme called pyruvate dehydrogenase.

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8
Q

In regards to NADH and FADH2, which one undergoes oxidation and which one undergoes reduction?

A

NADH: Reduction
FADH2: Oxidation
Reduction rxn: NAD + H+ +2e- -> NADH
Oxidation rxn: FAD + 2H+ + 2e- -> FADH2

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9
Q

Which processes occur in the mitochondrion and which one does not?

A

Krebs cycle and ETC in mitochondrion and Glycolysis occurs in the cytoplasm of the cell.

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10
Q

ATP Synthesis, The ETC:
Most of the usable energy obtained by the breakdown of carbohydrates and fats is derived from?

A

The transport of electrons.

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11
Q

The electrons from ___ NADH and ___ FADH2 molecules generated from _______ and the _________ transfer their electrons to molecular oxygen = ?

A

10 ; 2 ; glycolysis ; Krebs cycle ; a total of 32 ATP molecules

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12
Q

Describe the electron transport chain in mitochondria.

A

-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*

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13
Q

Describe Complex II (Succinate-Coenzyme Q oxidoreductase) in the ETC.

A

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.

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14
Q

Complexes I and II, despite their name, do not do what?

A

They do not operate in series, but both accomplish the same results: the transfer of electrons to Co-enzyme Q

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15
Q

What are the consequences of impaired protein degradation?

A

Vacuolation (paraptosis), protein aggregates, damaged organelles, impairment of cellular processes, and cell death.

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16
Q

“Impaired protein degradation is the underlying pathogenesis of degenerative disorders such as…?”

A

Neurodegeneration, muscle, and liver degeneration, lung disease, and **aging.

17
Q

What are the two parts of a proteasome?

A

The central cylinder and the proteasome cap.

18
Q

Describe the central cylinder of a proteasome.

A

The 20S core consists of four stacked heptameric rings:
Two outer alpha rings (structural) &
Two inner beta-rings (catalytical)

19
Q

Describe the proteasome cap.

A

Is comprised of receptors like Rpn 13, Rpn10, and Rpn 11 (DUB).

20
Q

What are the different states of the proteasome cap?

A

S1: Substrate accepting state.
S2: Commitment state
S3: Substrate translocation state

21
Q

What goes on during the substrate accepting state?

A

Rpn13 and Rpn10 recognize the poly-ubiquitin tag of the substrate that is targeted for degradation.

22
Q

What goes on during the commitment state?

A

Poly-ubiquitinated substrate is positioned in the ATPase ring and the poly-ubiquitin tag is cleaved by Rpn11 (DUB).

23
Q

What goes on during the substrate translocation state?

A

Substrate is unfolded and translocated from the ATPase ring into the CP.