Problem Based Learning

Carbon Fixation

TBF 3023

PLANT PHYSIOLOGY

Group Members

Munirah Bt Safiee D20091034844

Nurul Ain Bt Abdul Hamid

D20091034867

Nur Iliyana Bt Shafeai D20091034868

Muhammad Hafiz B Abd Kadir

D20091034812

How does carbon dioxide is fixed in C3 Plants?

What is C3 Plants?What is C3 Plants? Most of the plant are C3 plants about 95% of Most of the plant are C3 plants about 95% of

plant species on earthplant species on earth Called C3 because the CO2 is first Called C3 because the CO2 is first

incorporated into a 3-carbon compoundincorporated into a 3-carbon compound Examples of C3 plant are Examples of C3 plant are wheat, barley, wheat, barley,

potatoes and many morepotatoes and many more C3 plants flourish in cool, wet, and cloudy C3 plants flourish in cool, wet, and cloudy

climates where there is high concentration climates where there is high concentration of CO2 of CO2

If water is plentiful, the stomata can stay If water is plentiful, the stomata can stay open and let in more carbon dioxideopen and let in more carbon dioxide

CC33 plants cannot grow in hot area because  plants cannot grow in hot area because

Rubisco incorporates more oxygen Rubisco incorporates more oxygen into RuBP as temperatures increaseinto RuBP as temperatures increase

This leads to photorespirationThis leads to photorespiration

In dry areas, CIn dry areas, C33 plants close  plants close

their stomata to reduce water loss, but this their stomata to reduce water loss, but this stops COstops CO22 from entering the leaves and  from entering the leaves and

therefore reduces the concentration of therefore reduces the concentration of COCO22 in the leaves in the leaves

C3 plant anatomy C3 plant anatomy Involves only mesophyll cell Involves only mesophyll cell No krantz anatomy, only one type of chloroplast in No krantz anatomy, only one type of chloroplast in

mesophyll cellmesophyll cell CO2 fixation occur once only in mesophyll cells CO2 fixation occur once only in mesophyll cells Stomata open on the dayStomata open on the day Stomata close on hot and dry dayStomata close on hot and dry day Rubisco, the enzyme involved in photosynthesis, is Rubisco, the enzyme involved in photosynthesis, is

also the enzyme involved in the uptake of CO2also the enzyme involved in the uptake of CO2 Use rubisco to make a three-carbon compound as Use rubisco to make a three-carbon compound as

the first stable product of carbon fixationthe first stable product of carbon fixation Photosynthesis takes place throughout the leafPhotosynthesis takes place throughout the leaf

Leaf AnatomyLeaf Anatomy In C3 plants, bundle sheath cells do In C3 plants, bundle sheath cells do

not contain chloroplasts; carbon not contain chloroplasts; carbon fixation and Calvin Cycle reactions fixation and Calvin Cycle reactions occur in mesophyll cellsoccur in mesophyll cells

In C4 plants, the bundle sheath cells In C4 plants, the bundle sheath cells contain chloroplasts; carbon is fixed contain chloroplasts; carbon is fixed in mesophyll cells, then transported to in mesophyll cells, then transported to bundle sheath cells where Calvin bundle sheath cells where Calvin Cycle reactions occurCycle reactions occur

How does carbon dioxide fixation process in C4 plant?

What is C4 plant?What is C4 plant?C4 plant grow in tropical and subtropical C4 plant grow in tropical and subtropical regions.regions.

It is named for the 4-carbon atoms present It is named for the 4-carbon atoms present in the first product of carbon fixation in these in the first product of carbon fixation in these plants, in contrast to the 3-carbon atom plants, in contrast to the 3-carbon atom products in Cproducts in C33 plants. plants.

Carbon dioxide fixation is more efficient in c4 Carbon dioxide fixation is more efficient in c4 plant.plant.

C4 Plant AnatomyC4 Plant Anatomy

The anatomy :The anatomy : Contain two layers of green cell:Contain two layers of green cell:

The outer mesophyll cell layerThe outer mesophyll cell layer The inner bundle sheath cell layerThe inner bundle sheath cell layer

The arrangement of these cell layers The arrangement of these cell layers around vascular bundle is known as around vascular bundle is known as Kranz anatomy.Kranz anatomy.

Differences c3 and c4 plant Differences c3 and c4 plant

c4 Plant c4 Plant PhysiologyPhysiology

The physiologyThe physiology Faster grow rateFaster grow rate High light intensity and temperature High light intensity and temperature Stomatal opening may be minimised ( to lowering Stomatal opening may be minimised ( to lowering

transpiration rate)transpiration rate)• Minimised stomatal opening reduce the carbon Minimised stomatal opening reduce the carbon

dioxide intake dioxide intake

• To overcome:To overcome: The mesophyll cell absorb CO2 efficiently and The mesophyll cell absorb CO2 efficiently and

maintain high concentration in bundle sheath cell.maintain high concentration in bundle sheath cell. PEP carboxylase in c4 plant has a higher affinity PEP carboxylase in c4 plant has a higher affinity

for CO2 compared to RuBP carboxylase in C3 for CO2 compared to RuBP carboxylase in C3 plant and not combine with oxygen.plant and not combine with oxygen.

C4 pathway

The anatomy and physiology of C4 plant The anatomy and physiology of C4 plant give higher and efficient carbohydrate give higher and efficient carbohydrate production compared in C3 plant due to production compared in C3 plant due to the higher concentration of carbon dioxide the higher concentration of carbon dioxide in the c4 plant.in the c4 plant.

How does carbon dioxide fixation process in CAM plant?

Evolved in plants living in very dry or Evolved in plants living in very dry or arid conditions.arid conditions.

Members of CAM plants :Members of CAM plants :

- Crassulaceae- Crassulaceae

- Cactaceae- Cactaceae

- Euphorbiaceae- Euphorbiaceae

- Bromeliaceae (pineaple)- Bromeliaceae (pineaple)

The CAM pathway occurs at The CAM pathway occurs at differents TIMES but within the differents TIMES but within the same cell of a CAM plant; in same cell of a CAM plant; in the mesophyll cellthe mesophyll cell

NightStomata Open

chloroplast

vacuole

PEP

CO2

oxaloacetate

Malic acid

DayStomata Close

chloroplast

vacuole

PEP

CO2

Pyruvate

Malic acid

Calvin Cycle

Since the stomata is closed Since the stomata is closed during the day, this helps the during the day, this helps the plant prevent water loss as plant prevent water loss as well as prevent COwell as prevent CO22 from from entering the cellentering the cell

M PlaM Pla

Differences Between C3, C4 Differences Between C3, C4 and CAM Plants ?and CAM Plants ?

Separate reaction in Separate reaction in different celldifferent cell

C3C4

C3 plant:C3 plant: No chloroplast in bundle sheath but found in No chloroplast in bundle sheath but found in

mesophyll cellmesophyll cell Carbon fixation and Calvin cycle occur in Carbon fixation and Calvin cycle occur in

mesophyll cell.mesophyll cell. Stomata open during the dayStomata open during the day Mesophyll cell arranged in parallel row.Mesophyll cell arranged in parallel row.

C4 plant:C4 plant: Contain chloroplast in bundle sheath and Contain chloroplast in bundle sheath and

mesophyll cellmesophyll cell Carbon fixation occur in mesophyll cellCarbon fixation occur in mesophyll cell Calvin cycle occur in bundle sheath cell.Calvin cycle occur in bundle sheath cell. Stomata open during the dayStomata open during the day

ANATOMYANATOMY

CAM (CAM (Crassulacean Acid Metabolism )Crassulacean Acid Metabolism )

carbon fixation and Calvin cycle occur in carbon fixation and Calvin cycle occur in

mesophyll cell. (partitioning by the use of mesophyll cell. (partitioning by the use of

time)time)

Stomata close during the day and open at Stomata close during the day and open at

nightnight

habitat:habitat:

C3 plant:C3 plant: Live at moderate temperature and rainfallsLive at moderate temperature and rainfalls

C4 plant:C4 plant: Live at hot and dry climateLive at hot and dry climate

CAM plant:CAM plant: Live at warm and arid regions (desert Live at warm and arid regions (desert

environment)environment)

Carbon fixation:Carbon fixation:

C3 plants:C3 plants: Carbon dioxide undergo carbon fixation by Carbon dioxide undergo carbon fixation by

RuBPRuBP Form two 3-carbon molecules ( 3-Form two 3-carbon molecules ( 3-

phosphoglycerate)phosphoglycerate) Catalyzed by protein rubisco.Catalyzed by protein rubisco. Form carbohydrate and glyceraldehyde 3-Form carbohydrate and glyceraldehyde 3-

phosphate (G3P)phosphate (G3P)

C4 plant:C4 plant: Carbon acceptor : phosphoenolpyruvate Carbon acceptor : phosphoenolpyruvate

(PEP)(PEP) Form four-carbon ( oxaloacetate)Form four-carbon ( oxaloacetate) Catalyzed by PEP carboxylaseCatalyzed by PEP carboxylase

CAM plant:CAM plant: Fixation of carbon dioxide to oxaloacetate Fixation of carbon dioxide to oxaloacetate

occur during night.occur during night. Oxaloacetate stored as malic acids in Oxaloacetate stored as malic acids in

vacoule.vacoule.