Lecture 15: Intro to Metabolism

Question 1

Bioenergetics and Metabolism

Answer 1

• Metabolism involves catabolism of compounds releasing free energy used to generate ATP
• Energy used in anabolic reactions to synthesize larger molecules using smaller molecules
• Gibbs free energy influences the metabolic flux or conversion of metabolites through the pathways

Question 2

Standard Free Energy Change

Answer 2

• If K > 1, G is negative, reaction is exergonic(more P)
• If K < 1, G is positive, reaction is endergonic(more S)
• If K = 1, G = 0

Question 3

Thermodynamics and Biochemical Reactions

Answer 3

• Gibbs free energy under standard conditions depends on nature of reactants and concentration at equilibrium
• The cellular gibbs energy is dependent on cellular concentrations of substrate and product and G’
• An enzyme can couple a favorable and unfavorable reaction to produce an overall favorable reaction

Question 4

ATP

Answer 4

• Nucleotide made of adenine, ribose, and three phosphates
  
  • linked by phosphoanhydride bonds and ester bonds to sugar
• Involved in both catabolic and anabolic pathways via phosphate group transfer reactions
• Change in free energy dependent on structure and stability of substrates and products
• Free energy changes not fixed, polar phosphates are ionizable and pH dependent.

Question 5

Phosphoryl Transfer Potential in Muscle

Answer 5

• Phosphocreatine + ADP -> ATP + Creatine during rest
• ATP + Creatine -> Phosphocreatine + ADP using creatine kinase during exercise