ll. Energy Chem Energy types and units

What is the SI unit of

Joule (J)

What are the two main types of energy in biochemistry?

potential energy (stored energy in bonds) and Kinetic energy (energy of motion)

What does Gibbs free energy (ΔG) determine?

It determines whether a reaction is spontaneous (ΔG < 0) or requires energy input (ΔG > 0).

What is an exergonic reaction?

A reaction that releases energy and has a negative ΔG.

How does ATP store and release energy?

ATP stores energy in its phosphate bonds and releases it when the bond between the second and third phosphate groups breaks.

What is an endergonic reaction

A reaction that requires energy input and has a positive ΔG.

What do enzymes do to activation energy?

Enzymes lower the activation energy of a reaction. Activation energy is the minimum energy required for a chemical reaction to occur. By lowering this energy barrier, enzymes speed up reactions without being consumed in the process

What happens in an oxidation reaction?

In an oxidation reaction, a substance loses electrons, which often leads to an increase in oxidation state. This process is commonly associated with the gain of oxygen or loss of hydrogen in chemical reactions. Oxidation is always paired with reduction (where another substance gains the lost electrons), forming a redox reaction.

What is the purpose of NADH and FADH₂ in cellular respiration?

They are electron carriers that transport high-energy electrons to the Electron Transport Chain for ATP production.

What are the four main stages of cellular respiration?

1) Glycolysis, 2) Pyruvate Oxidation, 3) Krebs Cycle, 4) Electron Transport Chain

Which stage of cellular respiration produces the most ATP?

Electron Transport Chain (~34 ATP).

What happens to pyruvate before entering the Krebs cycle?

It is converted into Acetyl-CoA.

What is the final electron acceptor in the Electron Transport Chain?

Oxygen (O₂) combines with electrons and protons to form water (H₂O).

How does the Electron Transport Chain produce ATP?

It creates a proton gradient that powers ATP synthase to generate ATP.

What happens if oxygen is not available for the electron transport chain?

The ETC stops, and the cell undergoes fermentation.

What is fermentation, and when does it occur?

Fermentation occurs when oxygen is not available; it regenerates NAD⁺ and allows glycolysis to continue producing 2 ATP.

What is the difference between catabolism and anabolism?

Catabolism breaks down molecules to release energy, while anabolism builds molecules using energy.

What is metabolism?

Metabolism is the sum of all chemical reactions in an organism, including both catabolic and anabolic processes.