BIOL 201 Lecture Notes - Lecture 11: Atp Synthase, Peptide, Porphyrin

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crimsonjackal99

25 Feb 2013

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Redox reactions: each electron transfer is a redox reaction. One carrier is oxidized, and the other is reduced. Succinate + fad + 2e + 2h -> fumarate + fadh2 + 2e + 2h. The next reaction is fadh2 + 2 fe (+3) (nhi) -> fad + 2fe+2 (nhi) + 2h. Nadh - > nad+, with the electrons going to the first carrier. The electron donor, is the reducing agent, that causes a reduction. Standard redox potential e0", a voltage value ranks reducing power of electron donor/acceptor pairs. The more negative the e0", the more the reducing power. Direction of electron transfer is from the more negative to the more positive. The first reaction of the electron transfer chain is the transfer of nadh electron to coenzyme q, which is then to complex iii, to cytochrome c, finally to complex iv. In the first reaction, electrons flow from carriers with more negative e0" to more positive ones.

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Can you answer the following questions:

1. Carbon monoxide is considered toxic because it acts on Complex IV. How would the addition of carbon monoxide to actively respiring mitochondria affect the relative oxidation-reduction states of all components of the electron-transport chain?

A) All four complexes would remain oxidized because they function as a multisystem complex.

B) Complexes I and III would be reduced, but complexes II and IV would be oxidized because the

electrons come from FADH2 oxidation, not NADH.

C) Complexes I, II, and III would be oxidized but Complex IV would remain reduced.

D) Complexes I, II, and III would be reduced and Complex IV would be oxidized.

E) All four complexes would remain reduced because they function as a multisystem complex.

2. Electrons are not very soluble in hydrophobic environments such as a bilipid membrane. What evidence is there that electrons move from complex to complex through the lipid membrane?

A) Cytochrome C is the electron carrier in the membrane and undergoes a head-over-heel flip to set up the proton gradient.

B) Cytochrome C is the electron carrier in the membrane and contains a cydrophoric porphyrin center.

C) CoQ is the electron carrier within the membrane and seems to be confined to the respirasome.

D) CoQ is the electron carrier within the membrane and it contains a hydrophobic porphyrin center.

E) FeS clusters are the carriers within the membrane and the electrons move from one cluster to the

next in a chain-like fashion.

3. What is the rationale for saying that âelectrons flow down the electron-transport chainâ?

A) Electrons flow from oxidized carriers to reduced carriers in discrete steps like a staircase.

B) Electrons flow from half-reactions with more positive redox potentials to more negative.

C) Electrons flow from reactions that continuously generate negative free energy values.

D) Electrons flow from the outer surface to the inner surface, a top down perception.

E) Because we think of electrons flowing like a liquid, the only direction electrons can flow is down.

1. During the TCA cycle, four reactions occur in which a pair of electrons are transferred from a substrate to an electron accepting coenzyme. These reactions are catalyzed by?

2.During the TCA cycle, four reactions occur in which a pair of electrons are transferred from a substrate to an electron accepting coenzyme. These reactions are catalyzed by?

3.Potent respiratory poison, including carbon monoxide, azide and cyanide have their toxic effect by binding to the heme a3 site of _____.

4.The first step in the TCA cycle is the condensation of the two-carbon acetyl group with a four-carbon _____ to form a six-carbon citrate molecule?

5.The inner mitochondrial membrane is virtually devoid of ____, and and rich in ____, which are characteristics of bacterial plasma membranes.

6.Iron sulfur centers are joined to the protein by linkage to a sulfur atom of a/n ___.

7.Decarboxylation of pyruvate and transfer of the acetyl group to CoA , along with the reduction of NAD₊ is catalyzed by ___.

8.When FADH₂ is the electron donor, electrons are passed directly to ____ in the respiratory chain

9.With the exception of ____, all of the redox centers within the respiratory chain that accept and donate electrons are prosthetic groups.

10.It iis evident fromt eh net equation fo the TCA cycle that the primary products of the pathway are the reduced coenzymes _____.

11. Complex III catalyzes the transfer of electrons from ___ to ___.

12. The passage of a pair of electrons from NADH to ubiquinone in the respiratory chain is accompanied by movement of roughly four protons from (the) ___ to (the) ___.

13. When NADH is the electron donor, electrons pass the respiratory chain by means of ____.

14. The matrix of the mitochondrion has a gel-like consistency owing to the presence of a high conentration of _____.

These are questions I missed on a quiz the instructor does not post what the answers should be and has not responded to my emails please help.

Thanks,

Amber

1.Bacteriorhodopsin is a protein that has 7 alpha helices embedded in the cell membrane. As such, how many start-transfer and stop-transfer sequences would it need?

7 start transfer sequences, 6 stop transfer sequences

7 of each, in alternating fashion

4 start transfer sequences and 3 stop transfer sequences

7 start transfer sequences

2. The role of GTP hydrolysis by the Signal Recognition Particle during cotranslational translocation to the ER is

to release the SRP after docking to the translocon so translation can resume.

to open the gate/pore of the translocon into the ER.

to arrest translation so that synthesis does not finish before the peptide is delivered to the translocon.

to allow binding to the ribosome.

3. The cisternal maturation model is just one model that describes how objects might move through the Golgi. Some of the statements below describing the cisternal maturation model are correct and some are incorrect. Select all the incorrect descriptions.

There's no need for retrograde movement

Vesicles bud off from the Trans Golgi Network toward the plasma membrane

Vesicular tubules move materials from the cis to medial Golgi networks.

There are no vesicles moving in the anterograde direction

4. Select all statements that are correct concerning electron transport and ATP synthesis during photosynthesis in chloroplasts.

Each photosystem (I and II) pump protons.

Protons are pumped into the lumen of the thylakoid.

The bulb of the synthase projects into the stroma

Photosystem I is reduced directly by Photosystem II

5. Select all that are true about ATP synthesis with an F_oF₁ synthase complex.

Each ADP+Pi is transferred from one beta subunit in Open conformation to a second beta subunit in Loose conformation and finally to the 3rd beta subunit in the T conformation

As the gamma subunit rotates to each beta subunit, it forces them to the open state.

As the gamma subunit rotates to a particular beta subunit, the unit before it changes conformation to Tight and the one ahead of it changes to Loose

As the gamma subunit rotates to a particular beta subunit, the unit before it changes conformation to Loose and the one ahead of it changes to Tight

All 3 beta subunits are always in a different conformation (open, loose, or tight)

6. The number of ATPs per NADH generated by the electron transport system is higher than the number generated per FADH2 because __________.

		electrons from FADH₂ are not oxidized all the way to water
		NADH is converted to NAD⁺, which increases the charge gradient for ATP synthesis
		FADH₂ has a lower (less negative) redox potential than NADH does
		FADH₂ has a higher (more negative) redox potential than NADH does

BIOL 201 Lecture Notes - Lecture 11: Atp Synthase, Peptide, Porphyrin

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