How do c4 plants process enzymes?

Question

How do c4 plants process enzymes?

Answer 1

C4 Photosynthesis : C4 plants.

Called C4 because the CO2 is first incorporated into a 4-carbon compound.

Stomata are open during the day.

Uses PEP Carboxylase for the enzyme involved in the uptake of CO2. This enzyme allows CO2 to be taken into the plant very quickly, and then it "delivers" the CO2 directly to RUBISCO for photsynthesis.

Photosynthesis takes place in inner cells (requires special anatomy called Kranz Anatomy)

Adaptive Value:

Photosynthesizes faster than C3 plants under high light intensity and high temperatures because the CO2 is delivered directly to RUBISCO, not allowing it to grab oxygen and undergo photorespiration.

Has better Water Use Efficiency because PEP Carboxylase brings in CO2 faster and so does not need to keep stomata open as much (less water lost by transpiration) for the same amount of CO2 gain for photosynthesis.

C4 plants include several thousand species in at least 19 plant families. Example: fourwing saltbush pictured here, corn, and many of our summer annual plants

Answer 2

The most distinguishable anatomical feature of C4 leaf is the presence of Bundle sheath surrounding vascular bundles. This anatomical specialization is called "Kranz anatomy" (Kranz means wreath in German)

The C4 Pathway operates in two photosynthetic cells

1) Mesophyll and

2) Bundle sheath

a) First (Carbon di oxide) CO2 combines with Phospho Enol Pyruvic acid (PEP) which is already present in the leaf to form  the 4-carbon compound oxaloacetic acid (OAA), H3PO4 and H2O. ( Thats why named C4 cycle because the first compound formed is a "4 carbon" compound)

b) Oxaloacetic acid is converted into malic acid or aspartic acid (both have 4 carbons)

c) Then they are transported (by plasmodesmata) into a bundle sheath cell.

d) Here the 4-carbon compound is broken down into carbon dioxide,( which enters the Calvin cycle (C3 cycle) to form sugars and starch.) and Pyruvic acid.

e) Pyruvic acid (C3- 3 carbon compound), is then transported back to a mesophyll cell where it is converted back into PEP.

Then again Co2 combines with PEP ... step (a) continues.

Hope you understood!

(If you remember the number of carbons in the compound, it will be easier for you to guess what product is formed.. if you are studying advanced level of botany then you will HAVE to remember those because you will have to write the formulas of each acid.)