3.3.1 Cellular respiration harnesses energy of carbohydrates & other fuel molecules

Cellular respiration can be classified into 2 types:

Aerobic respiration 有氧呼吸

Anaerobic respiration 无氧呼吸

When “Cellular respiration” appears in a question, it means aerobic respiration if there’s no other information

Total function:

$$ C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP} $$

Two types of reaction:

1. Oxidation氧化
2. Reduction还原

Oxidizing agent电子受体

Reducing agent电子供体

The more reduced, the more energetic it is

NAD+, the oxidized form of NADH, is a coenzyme that act as a oxidizing agent

$$ NAD^+ + 2e^- + H^+ \rightarrow NADH $$

ADP is a coenzyme that picks up energy (energy carrier)

NAD is a coenzyme that picks up electron (electron carrier)

Cellular respiration stages:

1. Glycolysis 糖酵解: breaks down glucose into 2 molecules of pyruvate, occurs in cellular matrix

$$ C_6H_{12}O_6 + 2NAD^+ + 2ADP + 2P_i \rightarrow 2CH_3COCOO^- \text{ (pyruvate)} + 2NADH + 2ATP + 2H_2O + 4H^+ $$