key term - Carboxysome

Definition

Carboxysomes are protein-shelled microcompartments found in cyanobacteria and some chemoautotrophs, which contain enzymes for carbon fixation. They enhance the efficiency of the Calvin cycle by concentrating carbon dioxide around rubisco.

5 Must Know Facts For Your Next Test

1. Carboxysomes encapsulate the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco).
2. They play a crucial role in the carbon fixation process of photosynthetic prokaryotes.
3. The protein shell of carboxysomes helps to concentrate CO2 and reduce oxygen interference with rubisco.
4. Carboxysomes are considered a type of bacterial microcompartment (BMC).
5. Their presence is an adaptation to environments with low CO2 concentrations.

Review Questions

Related terms

Rubisco: An enzyme involved in the first major step of carbon fixation in the Calvin cycle.

Calvin Cycle:

A series of biochemical redox reactions that take place in the stroma of chloroplasts during photosynthesis.

Bacterial Microcompartments (BMCs): Protein-based organelles found in bacteria that compartmentalize metabolic processes.