Welcome to Cellular Energy & Thermodynamics

Explore the fundamental principles of energy flow in living systems

1
Anabolism & Catabolism
Watch molecular structures build up during anabolism when energy input exceeds output, and break down during catabolism when energy is scarce.
2
Energy Coupling
Discover how cells link energy-releasing reactions with energy-requiring reactions through ATP, the universal energy currency.
3
Sequential Pathways
Experience cellular respiration step-by-step: glycolysis, oxidation, Krebs cycle, and electron transport chain—producing 36 ATP from one glucose!
4
Order & Death
Witness what happens when energy stops: ion pumps fail, membranes deteriorate, proteins denature, DNA degrades, and disorder takes over.
PEEBEDU
Cellular Energy & Thermodynamics

Interactive Learning Module: Energy Flow in Living Systems

1. Anabolism and Catabolism: Energy Balance

Key Concept: When energy input > output, anabolism builds complex molecules from simple ones. When energy input < output, catabolism breaks down complex molecules for energy.

Energy Balance & Molecular Complexity

Energy In: 50
Energy Out: 30
Metabolism: ANABOLISM (Net Energy: +20 units/sec)
Molecular Stages:
  • Stage 1: Monomers (simple circles)
  • Stage 2: Polymer chain (linked circles)
  • Stage 3: Folded protein (globular structure)
  • Stage 4: Complex organelle (intricate structure)

Try This:
  • Increase energy input to drive anabolism → build complexity
  • Decrease energy input below output → catabolism breaks down structures
Thermodynamics Connection: Anabolism (building) requires energy input and decreases entropy locally. Catabolism (breaking down) releases energy and increases entropy.

2. Energy Coupling: Linking Reactions

Key Concept: Cells couple energy-releasing reactions with energy-requiring reactions to power cellular processes.

ATP: The Energy Currency

Endergonic Reaction (Requires Energy)

ADP + Pi + Energy → ATP

Phosphorylation

Click the floating phosphate to attach it and form ATP
A
P
P
High Energy Bond
Pi
Energy Absorbed!
+ΔG
⇄

Exergonic Reaction (Releases Energy)

ATP → ADP + Pi + Energy

Hydrolysis

Click the high energy bond to break it and release energy
A
P
P
High Energy Bond - Click Me!
P
Energy Released!
-ΔG
Real Examples:
  • ATP hydrolysis powers active transport across membranes
  • Electron transport chain couples oxidation to ATP synthesis
  • Cellular respiration couples glucose breakdown to ATP formation

3. Sequential Metabolic Pathways

Key Concept: Energy-related pathways are sequential, allowing controlled energy transfer. Each product becomes the next reaction's reactant.

Cellular Respiration Pathway Guide

Glucose
Glycolysis
→
Pyruvate
Oxidation
→
Acetyl-CoA
Krebs Cycle
→
e- Carrier
ETC
→
ATP
Energy!

Interactive Reaction Canvas

Objective: Convert all Glucose to ATP

Select an enzyme below, then click on molecules to catalyze reactions

1
Glucose
0
Pyruvate
0
Acetyl-CoA
0
e- Carrier
0
ATP
Why Sequential?
  • Control: Each step can be regulated independently
  • Efficiency: Energy is released gradually, not all at once
  • Safety: Prevents dangerous energy spikes that could damage the cell
  • Flexibility: Intermediates can be used for other pathways
Analogy: Think of it like descending a staircase versus jumping off a cliff. Both get you down, but the stairs (sequential pathway) release energy in controlled steps, while the cliff (single reaction) releases all energy at once - potentially destructive!

4. Loss of Order Results in Death

Key Concept: Significant loss of order or energy flow results in death. Living systems are highly ordered and require constant energy to maintain that order.

What Happens When Energy Stops?

Cell Membrane
▲
+
▲
+
▲
+
-
-
-
DNA
A
T
C
G
Electrochemical Gradient: Strong
1
Ion pumps fail

Loss of electrochemical gradients

Waiting
2
Membranes deteriorate

Cell contents leak out

Waiting
3
Proteins denature

Loss of cellular structure

Waiting
4
DNA degrades

Inability to reproduce or repair

Waiting
5
Entropy increases

Disorder takes over

Waiting
Summary: Life is a constant battle against entropy (disorder). Energy input must exceed energy loss to maintain the highly ordered state we call "alive."