BRAINCAKERespiratory Substrates
A respiratory substrate is any biological molecule that can be broken down in respiration to release energy and make ATP. The three main groups are carbohydrates, lipids and proteins.
Carbohydrates are the main substrate for most cells. Glucose is respired first. Stores of glycogen (in animals) and starch (in plants) are hydrolysed to glucose when needed. Brain cells and red blood cells depend on glucose. Other monosaccharides such as fructose and galactose can also enter glycolysis.
Lipids are used when carbohydrate is in short supply, for example during long periods of exercise or fasting. Triglycerides are hydrolysed into glycerol and fatty acids, which enter the respiration pathway at different points. Lipids are an important long-term energy store.
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Key terms in this lesson
- respiratory quotient
- The ratio of the volume of carbon dioxide produced to the volume of oxygen used in respiration over the same time.
More in Respiration
- ATP Synthase
- Creatine Phosphate
- Anaerobic Respiration - Plants and Microorganisms.
- Anaerobic Respiration - Mammals
- Energy Values of Carbohydrates, Lipids and Proteins
- Respiration of Lipids
- Respiration of Proteins
- Respiratory Quotient
All 19 lessons in Respiration · All OCR A-level Biology topics