c3 and c4 plants

Introduction

C3 plants

C3 is the so called “normal plant” process where they don’t have photosynthetic adaptations to reduce photorespiration. The C3 process uses the enzyme RuBisCO (First step of the Calvin Cycle) to fix CO2 from the air and obtain the 3-carbon organic intermediate molecule 3-phosphoglycerate. Majority of plants on earth (85%) are C3 plants, such as wheat, rice, soybeans, all trees, and sunflowers. 

C3 plants are typically found in cool wet climates such as Asia. Rice is usually found in wet (rainfed) upland regions for maximum growth. Their photosynthesis process is at best in cooler and wet areas hence the reason why they are found in those conditions.

Image of the C3 pathway. Carbon dioxide enters a mesophyll cell and is fixed immediately by rubisco, leading to the formation of 3-PGA molecules, which contain three carbons.

c4

The C4 process and the Calvin Benson cycle are not together but rather physically separated.The C4 cycle occurs in the mesophylls cells, and the calvin cycle happening in special cells around the leaf veins. These special cells are known as bundle sheath cells. The C4 cycle first O2 is fixed in the mesophyll cells to form a simple 4-carbon organic acid compound called oxaloacetate. This step is carried out by non-Rubisco enzyme (PEP carboxylase), this has a routine to bind the two oxygen. Oxaloacetate is then transformed into a molecule known as Malate. That can be moved into the bundle sheath cells. Inside these cells, malate breaks down, releasing co2. The co2 is then fixed by the Rubisco and converted into sugars by the Calvin Benson cycle.

C4 plants are typically found in conditions that are most favourable to photosynthesis such as hot, sunny climates. Some areas where they can be found are 

 

 

 

 

 

 

5 plants that undergo c4 photosynthesis

  1. Corn crops

  2. Sugarcane

  3. Sorghum

  4. Millets 

  5. Switchgrass

 

Environments for C4 plants 

C4 plants are typically found in conditions that are most favourable to photosynthesis such as hot, sunny climates. C4 plants can be found in areas such as warm temperature areas and opened grasslands.

 

Compare and contrast

In comparison the c3 plants and the c4 plants both use C02 to make 3 carbon glucose. As well they both have a method/strategy to minimize photo-respiration.

 To contrast, c3 plants use rubisco for the fixation of carbon dioxide, where C4 a non-rubisco enzyme for carbon fixation. As well the c3 plant is connected to the Calvin-benson cycle, whereas the c4 plants are separated physically.