Metabolism: Lesson 2 (Thermochemistry)

Question 1

Second Law of Thermodynamics:

Answer 1

• In every energy transfer or conversion, some of the useful energy is lost to the environment (ex. Wasted as heat). Reactions are never 100% efficient.
• This increases the entropy of the universe.

Question 2

Gibbs Free Energy:

Answer 2

Gibbs Free Energy - the energy thats available to do work.

• Check Notes for Equation

Question 3

Photosynthesis vs. Cellular Respiration

Answer 3

• Photosynthesis -
Endergonic: takes small molecules (CO2, H2O) and adds light energy to produce a higher energy molecule (glucose which gets stored as starch).

• Cellular Respiration -
Exergonic: takes high energy molecules (Glucose) and breaks it down to release energy (ATP) and smaller molecules (H2O & CO2).

—> Energy released gets used in other cellular processes.

Question 4

Energy Coupling:

Answer 4

• Cells can make Endergonic reactions happen by supplying them with the free energy released by an Exogenic reactions - Coupled Reactions.

Question 5

Catabolic Pathways:

Answer 5

• Complex molecules are broken down; releases free energy ().

Question 6

Anabolic Pathways:

Answer 6

• Builds complex molecules; consumes free energy ().

Question 7

ATP (PART 1)

Answer 7

• Living cells need a constant supply of energy as many of their processes require energy input.
• Free energy is supplied by ATP.
• Adenosine Triphosphate - the primary energy source of free energy in living cells.

1. 5- Carbon Sugar (Ribose)
2. Nitrogen Base (Adenine)
3. Phosphate Groups

—> Each phosphate group has a negative charge.
—> Their repulsion contributes to their stability of their bonds.

Question 8

ATP (PART 2)

Answer 8

• The Chemical bonds that link the phosphate groups together are high energy bonds.
• When a phosphate group is removed to form ADP and Pi, small packets of energy are released: -30.5 KH/ mol (lab).
• Phosphate groups require lower energy to break than energy released.
• Removed by Hydrolysis reaction and catalyze by enzyme ATPase.

Question 9

What’s ATP Used For?

Answer 9

Used for:

1. Chemical Work - synthesizing molecules for growth/ reproduction.
2. Transport Work - active, endocytosis, exocytosis.
3. Mechanical Work - muscle contraction, cilia/ flagella movement.

Question 10

ATP Synthesis:

Answer 10

• ADP + Pi —> ATP
• Process is cellular respiration.
• A single working muscle cell requires 600 million ATP per minute.
• Very little ATP in food we eat.
• Without our bodies being able to synthesize ATP we would need to consume about our body weight in ATP per day.
• In a working muscle cell the entire pool of ATP is recycled once each minute.
• Over 10 million ATP consumed and regenerated per second per cell.
• We use ATP to breakdown food & release energy in it… then we use some of that energy to reassemble ATP.