NAME : WAHYUNI

NIM : F05112025

CLASS A (PGMIPA U)

PHOTOSYNTHESIS : LIGHT REACTION , DARK REACTION (CALVIN

CYCLE) AND C3 PLANT, C4 PLANT, AND CAM PLANT

In plants, plants need water, carbon dioxide, and energy. It is in the need to

perform a chemical process which would produce glucose and oxygen to build up

a block at the plant, which is called photosynthesis. photosynthesis can also be

interpreted as the formation of carbohydrates from carbon dioxide (CO2) and

water (H2O) with the help of sunlight. Able to perform photosynthesis because

plants has cells that contain chlorophyll (green substance). In discovery

photosynthesis, sunlight energy absorbed by chlorophyll and converted to

chemical energy stored in the form of carbohydrates or other organic compounds.

The reaction proceeds as follows:

H2O + CO2 sunlight C6H12O6 +O2

klorofil

Light Reaction

Sunlight has waves and smallest particle or photons. These photons has

wavelengths, spectrum has wavelength in the the spectrum called photosynthetic

electromagnetic . Organism only use a little bit of electronic magnetic. Who

wavelengths is called visible light. which is about 400 nm-740nm (blue-red).

photosynthetic pigment contained aided by the wavelength which is derived from

the visible light range. color pigment comes from the wavelengths are reflected by

light. plants usually shows its leaf color is green, it is in because green plants so

reflected leaf colors usually appear green. Wavelengths while red and blue are

absorbed in the form of energy used for photosynthesis.

Below is a description of the light reaction:

sumber : www. wikipedia.id

The chemical reaction for photosynthesis occur in the chloroplast.

photosynthesis occurs in two processes which are the light reactions, which need

light and involving breakdown of water and release of oxygen, and the dark

reaction or Calvin cycle, which converts carbon dioxide into sugar .. in the

chloroplast there is a very small structure resemble disc called thylakoids , and is

located between the stroma membranes, dark reactions occur in the stroma. While

the light reactions occur in the thylakoid .Thylakoid which is usually on many

plants, which have a pair of Photosystem . Photosystem 1 and photosystem II,

which work together to produce the energy that will be used by the stoma to make

sugar performance dark reaction. In the thylakoid has a pigment and chlorophyll

molecule device, the device used to absorb photons. then in photosystem II are

excited 2e incoming photons then undergo resonance and converge to the center

of the chlorophyll electrons then enter the center of the chlorophyll and

transported by the transport of electrons, photons works not only on photosystem

II but also in photosystem I. The electrons lost from photosystem II is replaced by

a process called photolysis. Where water is oxidized to break the H + ions and

electrons while oxygen has a higher voltage so that experience excitation. then

electrons from potosistem II entered into photosystem I that then went into center

chlorophyll then transported by the electron transport which produces NADPH in

this process because of NADP + and the ATP synthesis H + ions and ADP entry

will then result ATP. So overall this light reactions produce ATP and NADPH

which later will be used in the dark reaction or Calvin cycle.

Dark reaction

Dark reaction is a reaction in the continuation of the light reactions of

photosynthesis. This reaction does not need light. Dark reactions occur in the

chloroplast is called the stroma. The material is a dark reaction of ATP and

NADPH, which is generated from the light reaction, and CO2, which is derived

from the free air. From this dark reaction, resulting glucose (C6H12O6), which is

necessary for the reaction catabolism. It was discovered by Melvin Calvin and

Andrew Benson, as it is also called the dark reactions of the Calvin-Benson.Pada

reaction dark reaction consists of three stages: carbon fixation, reduction and

regeneration of RuBP.

Calvin cycle

Below is a description of calvin cycle

Sumber: http://biologimediacentre.com/fotosintes 1

The dark reaction begins phase fixation, ribulose diphosphate molecule

binds 6 6 molecules of CO2 from the air and forming 6 molecules beratom C6

unstable. Reactions can occur because of the presence of photosynthetic enzymes.

The enzyme is Rubisco. RuBP is alosetrik enzyme stimulated by three types of

changes resulting from the lighting used for the fixation of chloroplasts (or

enzyme RuBP carboxylase / oxygenase). because the enzyme is an enzyme

RuBisCo the richest in the Calvin cycle, which then broke into 12 atoms C3 air

molecules known as 3-phosphoglycerate acid (APG / PGA) which is also known

by C3 plants. Furthermore, 3-phosphoglycerate acid has received 12 additional

phosphate group, and a 1.3-bifosfogliserat form derived from the reduction of

ATP to ADP and NADPH. Then, 1,3-bifosfogliserat into the reduction phase,

where the compound is reduced by H + from NADPH, which then turned into

NADP +, and 12 molecules formed fosfogliseraldehid (PGAL) is beratom 3C.

Furthermore, 2 molecular fosfogliseraldehid escape and brings together itself into

one glucose molecule that has the atoms 6C (C6H12O6). 10 molecules Remaining

from fosfogliseraldehid then into the regeneration phase, namely re-

establishment of ribulose diphosphate. In this phase, 10 6 molecules

fosfogliseraldehid turned into ribulose phosphate molecules. If it gets an

additional phosphate group, it will turn into ribulose phosphate ribulose

diphosphate (RDP), which then re-bind CO2 and underwent a dark reaction cycle.

The dark reaction produces APG (phosphoglycerate acid), APG

(fosfogliseraldehid), RDP (ribulose diphosphate), and glucose (C6H12O6).

But generally calvin cycle usually only occurs in C3 plants, as we know

the type C3 plant products early reduction of CO2 (CO2 fixation) is acid 3-

phosphoglycerate, or PGA. But at the C4 plants can not directly do calvin cycle in

photosyntesis because the that inhibit bundle sheat(Co2 gas inhibits turnover, O2

and H2O) in the alternative to do is change the initial product of CO2 reduction

(CO2 fixation through PEP) into oxaloacetate acid, malic , and pyruvate. While

the CAM plants, plants do not open its stomata during the day but at night so his

reaction was also different.

Differences C3, C4 and CAM plants

A fundamental difference between plant types C3, C4 and CAM are the

reactions that take place in it. In which the plants are initial products of type C3

reduction of CO2 (CO2 fixation) is acid 3-phosphoglycerate or PGA. Consists of

a set of chemical reactions that take place in the chloroplast stroma that does not

require energy from direct sunlight. Necessary energy source derived from the

light phase of photosynthesis. A set of such reactions occur simultaneously and

continuously. 3 requires as much energy as ATP. PGAL produced can be used in

the event that the materials to build the structural components of cells, for cell

maintenance and stored in the form of starch.

In C4 plants that became characteristic of the type is the initial product of

CO2 reduction (CO2 fixation) is acid oxaloacetate, malate, and pyruvate (the result

is that carbon acids C4). The reaction in the leaf mesophyll, which first reacts with

H2O to form HCO3 by the enzyme carbonic anhydrate. Having a sheath cells that

function in addition mesophyl so plants do not experience excessive transpiration.

Each molecule of CO2 is fixed requiring 2 ATP. C4 plants also experience such

Calvin cycle in C3 plants with the help of the enzyme phosphoenolpyruvate

carboxylase. C4 plants generally living in the tropics for example maize.

Whereas the type of CAM plants have leaves that are thick enough so that

the transpiration rate is low. Its stomata open at night. Starch is described through

the process of glycolysis and PEP shaping. Entering CO2 reacted with water after

such as C4 plants fixation by PEP and converted into malate. By day malic

passively diffuses out of the vacuole and decarboxylate. Doing the same with C3

plants during the day that is the Calvin cycle. Doing the same with C4 plants at

night that Hatch and Slack cycle. CAM plants generally live in areas of dried for

example Pineapple.

http://ipul-biologi.blogspot.com/2011/02/perbedaan-tanaman-jenis-c3-c4-dan-cam.html

so overall difference cycle C3, C4 and CAM are as follows :

Source http://2.bp.blogspot.com/_HGNB2IZO3yY/TF

Similarities C3 ,C4 and CAM Plants

Whereas similarities C3 plants, C4 and CAM photosynthesis which serves

to make the survival of the plants if there is only C3 plants then when oxygen in

the air to enter the plant only take O2 plants run into photorespiration

consequently resulting in increased plant respiration plant. with the C4 and CAM.

RuBP which will bind O2 in because too many of CO2, the CO2 is slightly C4

plants and CAM will be tied by the PEP.