Symbiotic nitrogen fixation

Definition

Symbiotic nitrogen fixation is a process where certain bacteria convert atmospheric nitrogen into a form that plants can use, such as ammonia. This mutualistic relationship benefits both the bacteria and the host plant, commonly legumes.

5 Must Know Facts For Your Next Test

1. Rhizobium is one of the most well-known bacteria involved in symbiotic nitrogen fixation.
2. The process occurs within specialized structures called root nodules in plants.
3. Leghemoglobin in root nodules helps maintain a low oxygen concentration to facilitate the activity of nitrogenase, the enzyme responsible for nitrogen fixation.
4. The fixed nitrogen provided by bacteria enhances plant growth and reduces the need for synthetic fertilizers.
5. Both parties benefit: plants receive essential nutrients, and bacteria gain carbohydrates and a protected environment.

Review Questions

Related terms

Nitrogenase: An enzyme complex that catalyzes the reduction of atmospheric nitrogen to ammonia.

Leghemoglobin: A protein found in legume root nodules that binds oxygen to protect nitrogenase.

Root Nodules: Specialized structures on plant roots where symbiotic nitrogen-fixing bacteria reside.