Carbon & Nitrogen
The Role of Carbon in Organisms
- Carbon is a ubiquitous chemical element in biology
- Carbon dioxide is the ultimate source of the element carbon in all biological systems
- Photosynthesis is the process that removes the carbon from the atmosphere
- Carbon is used to build
- Carbohydrates
- Proteins
- Lipids
- Nucleic acids
- Carbon is also used to build
- Storage compounds
- Such as starch and cellulose
- Storage compounds
- Carbon can be used in cell formation
- To build new biological molecules
- All organisms use processes in new cell formation
The Role of Nitrogen in Organisms
- Nitrogen is also a ubiquitous chemical element in biology
- Nitrogen fixation is the process that removes the nitrogen from the atmosphere
- Nitrogen is used to build
- Proteins
- Nucleic acids (DNA and RNA)
- Urea (an important waste product of protein metabolism that is excreted by animals)
- Nitrogen is a key part in building biomass because of its presence in all amino acids and, therefore, proteins
- Nitrogen exchanges with the environment via the nitrogen cycle
The Role of Phosphorus in Organisms
- Phosphorus is used to build
- Nucleic acids
- Some lipids such as phospholipids
Diagram of the Position of Phosphorus in Nucleic Acids and Phospholipids
Phosphate in DNA
Phosphate in phospholipids
Diagram of the key biological molecules required for living organisms
The key biological molecules for living organisms
Exam Tip
The key message in this topic is that elements are constantly being exchanged between organisms (organic molecules) and their environment. Organisms must absorb the elements from the environment in order to grow, reproduce and maintain their organization. When an organism dies, its elements are returned to the environment, to be reused by other life forms.
