Unit 2 Exam Review

Question 1

define exergonic:

Answer 1

releases free energy (spontaneous)

Question 2

define endergonic

Answer 2

energy is absorbed (non-spontaneous)

Question 3

define anabolism and catabolism

Answer 3

anabolism: building up of smaller molecules into larger ones
-ex: photosynthesis
Catabolism: breaking down large molecules into smaller ones
-ex: cellular respiration

Question 4

equation for a change in Gibbs free energy and explain each term

Answer 4

🔺G=🔺H - T🔺S

🔺G: change in Gibbs free energy
🔺H: change in heat energy
🔺S: change in entropy(randomness)

— if 🔺G is negative, then it is an exergonic reaction

Question 5

explain why spontaneous reactions have a -🔺G

Answer 5

• Energy is given off
• Increasing randomness of the universe

Question 6

what would happen if a cell reached metabolic equilibrium? What prevents cells from reaching equilibrium?

Answer 6

• it would die
• cells are open systems
• The constant flow of materials in and out of the cell keeps the metabolic pathways from ever reaching equilibrium

Question 7

trace the path of electrons during cell respiration from the time they are removed from glucose until they arrive at the final electron acceptor.

Answer 7

glucose > NAD+ > (reduced to) > NADH > (follows the electron transport chain) > oxygen

• final electron acceptor is oxygen

Question 8

how is the chemical energy stored prior to oxidative phosphorylation?

Answer 8

• out of glucose > stored in NADH

Question 9

how is ATP used in metabolic pathways?

Answer 9

• Coupled reactions
• dephosphorylated
• used to drive the anabolic reactions

Question 10

how do enzymes affect🔺G?

Answer 10

• they don’t
• lower Activation energy but don’t affect the change in free energy

Question 11

Account for all the products of glycolysis, oxidation of pyruvate, and the Krebs cycle

Answer 11

• glycolysis: 2 ATP, 2NADH, 2 pyruvate
• oxidation of pyruvate: 2 NADH > 6 ATP
• Krebs cycle: 2 ATP, 6 NADH, 2 FADH
  TOTAL: 34 ATP