*AMARPREET KAUR A/P GURNAM SINGHD20091034873

*NATASHA KAUR A/P MINDAR SINGHD20091034839

*YAASHINI A/P SELVARAJAHD20091034837

*MAZATUL AZRIN B. RAHMAN

D20091034846

*RIO RANDY ANAK UJANG

D20091034835

o Photosynthesis is the process where it will converts light energy into the chemical energy of sugars and other organic compounds

oprocess takes place in the chloroplasts = chlorophyll

oCarbon dioxide, water, and sunlight are used to produce glucose, oxygen, and water.

o cellular respiration converts sugar into ATP.

6CO6CO22 + 12H + 12H22O + light → CO + light → C66HH1212OO66 +  + 6O6O22 + 6H + 6H22OO

CHLOROPLASTCHLOROPLAST10 to 100 chloroplasts

Enclosed by a double membrane

phospholipid inner and outer membrane

Intermembrane space between them

Inside the membrane is the stroma

Stroma contains stacks (grana) of thylakoids

Outer and inner membranes: protective coverings that keep chloroplast structures enclosed.

Stroma: Site of conversion of carbon dioxide to sugar.

Thylakoid: Site of conversion of light energy to chemical energy.

Grana: dense layered stacks of thylakoid sacs. Sites of conversion of light energy to chemical energy.

Chlorophyll: a green pigment within the chloroplast. Absorbs light energy.

*MECHANISM MECHANISM

INVOLVEINVOLVE3 basic step in photosynthesis:

1.Energy is captured from the sunlight.

2.Light energy is converted into chemical energy in the form of ATP and NADPH.

3.Chemical energy is used to power the synthesis or organic molecules (e.g. carbohydrates) from carbon dioxide (CO2).

*Involved :

Light reaction- photosystem 1 & 2

Dark reaction – calvin cycle

First stage of photosynthesis

Energy is converted into chemical energy, in the form of the energy-carriers ATP and NADPH.

The formed NADPH and ATP drive the reduction of CO2 to more useful organic compounds, such as glucose.

Take place in the thylakoid membrane inside a chloroplast

Meanwhile, light-independent reactions take place at the outside of the thylakoid membrane that is at stroma.

Thylakoid membrane contains some integral membrane protein complexes that catalyze the light reactions.

*Major protein complexes in the thylakoid membranePhotosystem I (PSI)Photosystem II (PSII)Cytochrome ATP synthase

Light reactions occurs in the thylakoid stacks of the grana. Sunlight is converted to chemical energy in the form of ATP (free energy containing molecule) and NADPH (high energy electron carrying molecule). Light strikes chlorophyll a in such a way as to excite electrons to a higher energy state. In a series of reactions the energy is converted (along an electron transport process) into ATP and NADPH. Water is split in the process, releasing oxygen as a by-product of the reaction. Oxygen is released through the stomata. Both ATP and NADPH are used in the dark reactions to produce sugar.

*The net-reaction of all light-dependent reactions in oxygenic photosynthesis is:

2H2H22O + 2NADPO + 2NADP++ + 3ADP + 3P + 3ADP + 3Pii → O → O22 + + 2NADPH + 3ATP2NADPH + 3ATP

Chemical reactions that convert CO2 and other compounds into glucose.

Occur in the stroma.

Three phases to the light-independent reactions(calvin cycle)

•carbon fixation

• reduction reactions

• ribulose 1,5-bisphosphate (RuBP) regeneration.

*Occurs only when light is available

*Plants do not carry out the Calvin cycle by night, they instead release sucrose into the phloem from their starch reserves

*This process happens when light is available independent of the kind of photosynthesis (C3 carbon fixation, C4 carbon fixation ,and Crassulacean Acid Metabolism);

* CAM plants store malic acid in their vacuoles every night and release it by day in order to make this process work

Carbon dioxide is converted to sugar using ATP and NADPH.

Carbon dioxide is combined with a 5-carbon sugar creating a 6-carbon sugar.

The 6-carbon sugar is eventually broken-down into two molecules, glucose and fructose.

These two molecules make sucrose or sugar.

Many factors affect the rate at which photosynthesis occurs.

Because water is one of the raw materials of photosynthesis, a shortage of water can slow or even stop photosynthesis.

Plants that live in dry conditions, such as desert plants and conifers, have a waxy coating on their leaves that reduces water loss.

Depends on enzymes that function best between 0°C and 35°C.

Temperatures above or below this range may damage the enzymes, slowing down the rate of photosynthesis.

very low temperatures - photosynthesis may stop entirely.

very high temperatures - enzymes are denatured.

Optimum temperature: 25oC to 35oC

Since both the stages of photosynthesis require enzyme activity,

The temperature has an effect on the rate of photosynthesis.

Graph Showing Effect of Temperature on Rate of Photosynthesis

Increasing light intensity increases the rate of photosynthesis.After the light intensity reaches a certain level - plant reaches its maximum rate of photosynthesis.The level at which light intensity no longer affects photosynthesis varies from plant type to plant type.Light intensity increases:. the rate of the light-dependent reaction, and photosynthesis also increases As light intensity is increased, the rate of photosynthesis is eventually limited by some other factor. Chlorophyll a is used in both photosystems. PSI absorbs energy most efficiently at 700 nm and PSII at 680 nm.Light with a high proportion of energy concentrated in these wavelengths will produce a high rate of photosynthesis.

The rate at which a plant carries out photosynthesis depends in part on its environment.•Plants that grow in the shade carry out photosynthesis at low levels of light.•Plants that grow in the sun, such as desert plants, typically carry out photosynthesis at much higher levels of light.

0.1% of carbon dioxide in the atmosphere increases the rate of photosynthesis significantly.

This is achieved in the greenhouses which are enclosed chambers where plants are grown under controlled conditions.

The concentration is increased by installing gas burners which liberate carbon dioxide as the gas burns.

Crops like tomatoes, lettuce are successfully grown in the greenhouses.

These greenhouse crops are found to be bigger and better-yielding than their counterparts growing in natural conditions.

An increase in the carbon dioxide concentration increases the rate at which carbon is incorporated into carbohydrate in the light-independent reaction

Rate of photosynthesis generally increases until limited by another factor.

Light Intensity