Bioenergetics

Question 1

Gº

Answer 1

Free energey change at standard conditions (25C, 1atm, 1M)

Question 2

Gº’

Answer 2

Free energy change at standard physicological conditions

Question 3

Endergonic

Answer 3

Same as endothermic (G is postive = nonspontaneous)

Question 4

Exergonic

Answer 4

same as exothermic (G is negative = spontaneous)

Question 5

ATP to ADP

Answer 5

yields around -30 kj/mol

Question 6

Substrate level phosphorylation

Answer 6

Coupling of exergonic reactions drive endergonic ATP formation. i.e glycolysis and citric acid cycle

Question 7

Oxidative Phosphorylation

Answer 7

Formation of ATP by harnessing electrochemical gradient i.e. mitochondrial matrix

Question 8

How is ATP used

Answer 8

• Hydrolysis
  
  • Couple to other unfavorable rxns
• Phosphoryl group transfers
  
  • puts phosphate groups on other molecules
• Phosphorylation using ATP
  
  • How enzymes are controlled

Question 9

Metabolism

Answer 9

Glucose –> ATP

• Glycolysis
• Citric Acid cycle
• Electron transport chain

*Humans are obligate aerobes

Question 10

Glycolysis

Answer 10

Input: glucose, 2 ATP

Products: 2 Pyruvate, 4 ATP, 2 NADH

Three irreversible steps: Step 1, 3, and 10

*10 total steps

Question 11

Destination of Pyruvate

Answer 11

• Citric Acid Cycle
  
  • pyruvate to acetyl-CoA
• Fermentation
  
  • Lactic Acid
  • Ethanol
• Gluconeogenesis
  
  • During fasting pyruvate can be converted to glucose via reverse glycolysis
    
    • Steps 1,3,10 need different reverse mechanisms

Question 12

Citric Acid Cycle

Answer 12

Input: Acetyl-CoA and oxaloacetate

Products: oxaloacetate, 3 NADH, 1 FADH2, and 1 GTP

More energy yielded with NADH than FADH2

*2 cycles per glucose*

Question 13

Electron Transport Chain

Answer 13

Input: All of NADH and FADH2 produced during Glycolysis and CAC

Products: H+ gradient made

Question 14

ATP synthase

Answer 14

Electrochemical gradient is used to make ATP

2. 5 ATP/NADH
3. 5 ATP/FADH2

In total: about 38 ATP produced through the whole process

Question 15

Allosteric Control

Answer 15

• Downstream product inhibiting an upstream enzyme
• Eventual target molecules is often the major inhibitor or upstream product
  
  • ATP acts as an allosteric inhibitor of PFK-1 (rate-limiting step of glycolysis)
• Most likey step to be regulated is the “committed step”

Question 16

Pentose Phosphate Pathway

Answer 16

*NADPH synthesis and Ribose-5-Phosphate

NADPH is an important reducing molecule

R-5-P is used to synthesize nucleotides

Input: G-6-P

Output: R-5-P (funneled into nucleotide synthesis