Bioenergetics

Question 1

What are the two components which make up adenosine?

Answer 1

ribose and adenine

Question 2

Via what kind of bond do phosphates attach to adenosine?

Answer 2

phosphate ester bond

• the OH of adenosine’s free CH₂OH group bonds to a phopshate

Question 3

What bond holds the most energy in ATP?

And what is the general term for such a high energy bond?

Answer 3

the anhydride centered around the O between two Ps

macroergic bonds are high energy bonds

Question 4

What is the energy released per mole of dephosphorylated ATP?

Answer 4

30 kJ per mole

Question 5

How can more ATP be formed from only free ADPs without the presence of free phosphates?

Answer 5

via the enzyme adenylyl kinase which converts 2 ADP into one ATP and one AMP

Question 6

What is the reversible equation of the creatine system?

Answer 6

ATP + Creatine <—> ADP + Creatine Phosphate

Question 7

What kind of special high energy bond can creatine form?

Where on the molecule?

Answer 7

Phosphoamide

• a macroergic bond between phosphate and creatine
• forms when phosphate bonds with the terminal amino group on creatine

Question 8

What are the overall inputs and outputs of glycolysis?

Answer 8

2 ATP in (forms two 1,3 BPG)

4 ATP out (two for each BPG)

plus

2 Pyruvates or Lactic Acids (anaerobic)

(and 2 NADH plus 2 H⁺ )

Question 9

What are the 2 important molecules involved in the ATP forming steps of glycolysis?

And what kind of ATP creation is this?

Answer 9

1,3 - Bisphosphoglycerate

and

Phosphoenolpyruvate

• take part in substrate level phosphorylation

Question 10

What kind of bond is the high energy bond in 1,3 BPG?

Answer 10

• a macroergic anhydride between glycerols C1 and phosphate

Question 11

What is the overall reaction of the first ATP producing step of glycolysis?

Answer 11

1,3 BPG + ADP —> 3 PG + ATP

• notice it is irreversible

Question 12

What is the high energy bond of the 2nd ATP producing step of glycolysis?

Answer 12

enol-ester

• between the central carbon of the enolpyruvate portion of PEP and its phosphate

Question 13

What is the reaction equation for the 2nd ATP producing step of glycolysis?

And what is the fate of the dephosphorylated molecule?

Answer 13

PEP + ADP —> ATP + enolpyruvate

• note it is irreversible
• enolpyruvate is tautomerized to pyruvate

Question 14

Where does substrate level phosphorylation happen in the Krebs cycle?

Answer 14

GDP is phosphorylated to GTP via Succinyl-CoA

Question 15

What are the important products of the krebs cycle which become substrates for the reactions of the ETC?

Answer 15

NADH

H+

and FADH2

Question 16

What complexes are involved in NADH+ transportation in the respiratory chain?

And what do these complexes do to help ATP synthase work?

Answer 16

I, III and IV

(II takes up FADH2 only)

• they pump protons into the intermembrane space to create and H+ concentration gradient which drives ATP synthase’s phosphorylation of ADP

(complex II does NOT pump protons in)

Question 17

What is the function of coenzyme Q within the ETC?

Answer 17

• acts as an electron carrier from complex I to II to III

Question 18

Where does oxygen fit into the ETC?

Answer 18

It is reduced to water at complex IV

Question 19

What poisons can inhibit the respiratory chain and where?

Answer 19

oligomycin - inhibits Fo complex of ATP synthase

HCN - inhibits complex IV

Question 20

What happens to the respiratory chain when there is an abundance of ATP?

What is this process called?

Answer 20

Acceptor Control

• since there is less ADP for ATP synthase to use, the respiratory chain slows down

Question 21

What do “uncouplers” do?

What are two examples?

Answer 21

• they dissipate the proton gradient between the IM space and the mitochondrial matrix
• this ‘uncouples’ the ETC from its ability to drive ATP synthase

D-Nitrophenol binds to H in IM space and carries it to matrix

Thermogenin in brown fat uncouples for the purpose of heat creation