oxidative phosphorylation

Question 1

electron transport

Answer 1

Electrons generally fall in energy through the chain - from complexes I and II to complex IV

Question 2

How many ATP’s made per electron pair passed through the chain?

Answer 2

e- transport chain yields 10 H+ pumped out per electron pair from NADH to oxygen

4 H+ flow back into matrix for each ATP molecule synthesised

10/4 = 2.5 for electrons entering as NADH

For electrons entering as succinate (FADH2), about 6 H+ pumped per electron pair to oxygen

6/4 = 1.5 for electrons entering as succinate

Question 3

see powerpoint for

Answer 3

step, product, ATP yield per glucose and system table

Question 4

see powerpoint for

Answer 4

inhibitors of electron transport

Question 5

cyanide poisoning

Answer 5

The toxicity of cyanide is largely attributed to the cessation of aerobic cell metabolism.

Cyanide causes intracellular hypoxia by reversibly binding to the cytochrome oxidase a3 within the mitochondria.

Cytochrome oxidase a3 is necessary for the reduction of oxygen to water in the fourth complex of oxidative phosphorylation.

Binding of cyanide to the ferric ion in cytochrome oxidase a3 inhibits the terminal enzyme in the respiratory chain and halts electron transport and oxidative phosphorylation.

This downward cascade is fatal if not reversed!!

Question 6

use in terrorism and murder

Answer 6

In 1995, a device was discovered in a restroom in the Kayabacho Tokyo subway station, consisting of bags of sodium cyanide and sulfuric acid with a remote controlled motor to rupture them in what was believed to be an attempt by the Aum Shinrikyo cult to produce toxic amounts of hydrogen cyanide gas. Aum Shinrikyo are a nice bunch who also manufactured large quantities of nerve gasses (sarin and VX) and have killed with sarin in Tokyo.

In 2003, Al Qaeda reportedly planned to release cyanide gas into the New York City Subway system. The attack was reportedly aborted because there would not be enough casualties!

Question 7

Neil Heywood

Answer 7

“an internal Chinese report confirmed that Heywood died from potassium cyanide added to his drink”

The Tylenol murders were a series of poisoning deaths resulting from drug tampering in the Chicago area in 1982. The victims had all taken Tylenol-branded acetaminophen (paracetamol) capsules that had been laced with potassium cyanide. Seven people died in the original poisonings, with several more deaths in subsequent copycat crimes. Enough cyanide to kill in the small 500mg capsules.

Richard Leonard Kuklinski (April 11, 1935 – March 5, 2006) was an American contract killer known as “the iceman” who favoured cyanide as a means of killing.

Question 8

Jonestown

Answer 8

“Jonestown” was the informal name for the Peoples Temple Agricultural Project formed by the Peoples Temple, an American religious organization under the leadership of Jim Jones, in Guyana.

On November 18, 1978, over 900 people died in the remote commune, at the nearby airstrip in Port Kaituma, and in Georgetown, the capital city.

A total of 909 Americans died in Jonestown, all but two from cyanide poisoning, in an event termed “revolutionary suicide” by Jones.

Question 9

industrial source of cyanide

Answer 9

insecticides 
photographic solutions
metal polishing materials
jewelery cleaners
acetonitrile
electroplating materials
synthetic products such as rayon, nylon, polyurethane foam, insulation and adhesive resins

Question 10

natural sources of cyanide

Answer 10

seeds and fruit pits of Prunus species

Question 11

environmental sources of cyanide

Answer 11

smoke inhalation in closed-space fires

Question 12

latrogenic sources of cyanide

Answer 12

sodium nitroprusside infusion

Question 13

sodium azide

Answer 13

Sodium azide is best known as the chemical found in automobile airbags and airplane escape CHUTES. An electrical charge triggered by automobile impact causes sodium azide to explode and convert to nitrogen gas inside the airbag/CHUTE.

Sodium azide is used as a chemical preservative in hospitals and laboratories. Accidents have occurred in these settings. In one case, sodium azide was poured into a drain, where it exploded and the toxic gas was inhaled.

Sodium azide is used in agriculture (farming) for pest control.

Sodium azide is also used in detonators and other explosives.

Azide inhibits cytochrome oxidase by binding irreversibly to the heme cofactor in a process similar to the action of carbon monoxide. Sodium azide particularly affects organs that undergo high rates of respiration, such as the heart and the brain, this is not, on the whole, a good thing.

Question 14

how many protein complexes in the inner mitochondrial membrane are involved in electron transport?

Answer 14

four

Question 15

what shuttles between protein complexes in electron transport?

Answer 15

A lipid soluble coenzyme (UQ, CoQ) and a water soluble protein (cytochrome c)

Question 16

what do NADH and FADH2 do in electron transport?

Answer 16

release their high-energy electrons and hydrogens to specialized molecules called flavoproteins

Question 17

what are flavoproteins

Answer 17

metal-containing ions and cytochromes found in the inner membrane (cristae) of the eukaryote mitochondrion.

Question 18

what do the electrons do to NADH and FADH2 in electron transport?

Answer 18

Electrons reduce and oxidize these molecules as they pass from one to the next, releasing small amounts of energy.

Question 19

lower energy electrons

Answer 19

are attracted to singlet oxygen brought into the mitochondrial matrix by diffusion.

Question 20

what does Oxygen serves as in the process of complete aerobic respiration.

Answer 20

the final electron acceptor

Question 21

what happens to the Hydrogens from NADH and FADH2

Answer 21

pumped outside the membrane and begin to accumulate, forming a concentration (proton) gradient.

Question 22

what is the result of the hydrogens being pumped outside the membrane?

Answer 22

This lowers the pH and results in protonmotive force that serves to drive the hydrogen ions through protein channels called ATP synthase (ATPase) molecules.

Question 23

what happens as the hydrogens pass through ATPase

Answer 23

the enzyme links inorganic phosphates present in the cytoplasm or mitochondrial matrix to ADP molecules.

Question 24

what happens once the hydrogens are in the cytoplasm

Answer 24

each pair of hydrogens is bound to oxygen, forming water. The complete breakdown of sugar and production of new ATP in the using oxygen as the final electron and hydrogen acceptor is called oxidative phosphorylation.