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Biochemistry 2019 > Lecture 25 > Flashcards

Lecture 25 Flashcards

1
Q

Describe the structure of mitochondria (how many membranes are there and what level of permeability do these membranes have?)

A

2 membranes
Outer membrane: permeable due to porins in it (aka VDAC)

Inner membrane: impermeable and folded into cristae

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2
Q

State the 2 compartments that compose a mitochondria. Which of these compartments is the site of the TCA cycle/fatty acid synthesis and where does Oxidative phosphorylation occur?

A

Intermembrane Space

Matrix: site of TCA cycle/fatty acid synthesis

Oxidative Phosphorylation occurs in the inner membrane

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3
Q

What organism were mitochondria derived from? explain the process by which this occurred and the strongest indication that supports this.

A

Rickettsia prowazekii

This occurred via an endosymbiotic event that occured

Human mitochondrial DNA is significantly different than the DNA of all other parts of the cell

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4
Q

Describe what pathway OxPhos conducts, using the high energy electrons of NADH and FADH2 (produced by the TCA cycle). (how many complexes and describe the basic function of these complexes)

A

The Electron Transport Chain, which is composed of 4 protein complexes

3 of these complexes pump protons from the matrix to the intermembrane space

ATP Synthase (the 5th complex not mentioned in this lecture) synthesizes ATP when these protons enter ATP synthase in order to flow back into the matrix

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5
Q

State the 3 criteria that describes a successful OxPhos reaction

A
  1. transfer electrons from NADH/FADH2 to O2
  2. Establish a proton gradient across the inner mito membrane
  3. To Synthesize ATP
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6
Q

Electrons are transferred from NADH to O2 via 3 large protein complexes. state them and determine whether this electron flow in exergonic or endergonic.

A

NADH Q oxidoreductase (complex I)

Q cytochrome c oxidoreductase (complex III)

Cytochrome c oxidase (complex IV)

This electron flow is exergonic

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7
Q

Which complexes are referred to as the respirasome?

A

Complex I, III, and IV

not Complex II

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8
Q

What is the name of the only complex in the ETC that doesn’t pump protons? (name and complex number) state it’s function and any other proteins involved in this function.

A

Succinate Q reductase (Complex II): allows the entry of the electrons from FADH2, into the ETC

Complex II does this by transferring the electrons to FeS and then to Q (forming QH2)

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9
Q

True or False:

Succinate Q reductase pumps protons out of the mito matrix and into the intermembrane space of the mito. explain.

A

False

Succinate Q reductase really only removes electrons from FADH2 and passes them on to Coenzyme Q

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10
Q

What is another name for Coenzyme Q? Describe the function and physical characteristics of coenzyme Q.

A

Coenzyme Q = Ubiquinone

Coenzyme Q transfers electrons from Succinate Q reductase and NADH Q oxidoreductase TO Q cytochrome c oxidoreductase

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11
Q

What is the most common form of Coenzyme Q (aka Ubiquinone)?

A

CoQ10

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12
Q

What is the final component of the ETC? what is its basic function?

A

Cytochrome C

It moves electrons from complex III (Q cytochrome c oxidoreductase) to complex IV (Cytochrome c oxidase)

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13
Q

Why does Complex II (Succinate Q reductase) only remove electrons from FADH2 and not from NADH?

A

because it does not have enough relative free energy to harvest electrons off of NADH, only Complex I (NADH Q oxidoreductase) has enough energy to do that.

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14
Q

State the full name (not the complex number) of the enzyme complex that corresponds with the following prosthetic groups.

FMN
Fe-S

A

NADH-Q oxidoreductase

FMN
Fe-S

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15
Q

State the full name (not the complex number) of the enzyme complex that corresponds with the following prosthetic group.

FAD
Fe-S

A

Succinate-Q reductase

FAD
Fe-S

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16
Q

State the full name (not the complex number) of the enzyme complex that corresponds with the following prosthetic group.

Heme bH
Heme bL
Heme C1
Fe-S

A

Q-cytochrome c oxidoreductase

Heme bH
Heme bL
Heme C1
Fe-S

17
Q

State the full name (not the complex number) of the enzyme complex that corresponds with the following prosthetic group.

Heme a
Heme a3
CUA and CUS

A

Cytochrome c oxidase

Heme a
Heme a3
CUA and CUS

18
Q

Which ETC Complex serves as the first point of entry of electrons from NADH? (include all 3 of the synonymous names for this complex)

A

Complex I
(NADH Dehydrogenase)
(NADH-Q oxidoreductase)

19
Q

Complex I in the ETC is coded for by what type of DNA?

A

nuclear AND mitochondrial DNA

20
Q

What specific part of NADH Q oxidoreductase (complex I) undergoes oxidation-reduction reactions?

A

Iron Sulfur Clusters present in complex I undergo oxidation-reduction reactions

21
Q

Complex II is unique in that it serves as a connector for what 2 pathways? what else is significant about Complex II and FADH2 and it’s protons?

A

Complex II connects the TCA to the OxPhos reactions of the ETC

Complex II does not allow FADH2 to leave the complex and does NOT pump protons

22
Q

Why is there less ATP synthesized from the oxidation of FADH2, compared to NADH?

A

Complex II (which handles the electrons from FADH2) only transfers the electrons from FADH2 and does NOT pump protons from FADH2 (into the intermembrane space)

23
Q

Describe the flow of electrons in the ETC. (remember there is more than 1 source of electrons)

A

NADH electrons enter Complex I and FADH2 electrons enter Complex II

Now all electrons in Complex II pass through QH2 and enter Complex III

Electrons in Complex III then into Cytochrome C

Reduced Cytochrome C transfers the electrons to oxygen (4 electrons will reduce the Oxygen into Water)

24
Q

Which Complex has 2 heme groups and 3 Cu groups?

A

Cytochrome c Oxidase (complex IV)

25
Q

Name the 3 ROS species that can be generated by partial reduction of O2. What is considered to be a toxic derivative of Oxygen?

A
  1. Superoxide Ion (oxygen with an extra electron)
  2. Peroxide Ion
  3. Hydroxyl Radical (OH)

Free radicals are considered to be toxic derivatives of Oxygen

26
Q

What is the function of SOD (Superoxide dismutase)? What about Catalase?

A

SOD converts the dangerous free radical species of superoxide into hydrogen peroxide

Catalase converts 2 molecules of hydrogen peroxide into oxygen and water
(2H2O2 –> O2 + H2O)

27
Q

Over production causes _____, where as normal levels of free radicals are neccesary for physiologically normal _____ processes.

A

damage

signaling

28
Q

Besides SOD and Catalase, state 3 more antioxidants to know.

A

Glutathione peroxidase

Vitamin E

Vitamin C

29
Q

There are 2 types of SOD, SOD1 and SOD2. State the metals these feature and where in the cell they are normally found.

A

SOD1:
Cu/Zn
Cytosolic

SOD2:
Mn/Zn
Mitochondrial

Biochemistry 2019 (32 decks)

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