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Photosynthesis in Plants - TOMMY LIU, CHLOROPLASTS: THE CENTRE OF…
Photosynthesis in Plants - TOMMY LIU
THE PRODUCTS (OUTPUTS)
Glucose (Sugar)
Plants use these sugars to make other carbohydrates, including starches. It can also be used to make compounds such as proteins and lipids in the plant cell.
Oxygen
Oxygen is a waste product, produced during the light dependant reaction within the thylakoid. Oxygen is the gas we all breathe in.
THE REACTANTS (INPUTS)
Carbon dioxide can get in the plant through tiny pores in the leaves called stomata. Oxygen can also be released in the stomata as a waste product after the light dependant reaction.
Photons from the sun are absorbed by light absorbing molecules called pigments. The most important pigment in plants is chlorophyll.
Water (H2O) is absorbed in the plant's roots by tiny tissues called xylem. This process is called osmosis.
Brief Definition: A complex process in which plants and other organisms absorb light from the sun in order to convert water and carbon dioxide, into glucose and oxygen. In more simpler words, light energy is being transformed into chemical energy.
6 CO2 + 6 H2O + light --> C6H12O6 + 6 O2
FACTORS AFFECTING PHOTOSYNTHESIS:
Temperature. Photosynthesis enzymes work the best between 0°C and 35°C
Light intensity. Brighter levels = faster photosynthesis.
Water levels. Water levels affect the rate of photosynthesis
CHLOROPLASTS: THE CENTRE OF PHOTOSYNTHESIS
These organelles contain thylakoids, a flat, bag-shaped membrane. Thylakoids are arranged by connecting to one another forming a stack called grana (Plural for granum)
Chlorophyll and other pigments are found in the thylakoids.
Thylakoids is where the light dependant reaction takes place.
Stroma is the liquid-filled space found in the thylakoids.
STAGE 2: LIGHT INDEPENDENT REACTIONS
LOCATION: STROMA OUTSIDE THE THYLAKOIDS
CREATES GLUCOSE AND HIGH ENERGY SUGARS
STEP 1: 5C (5 carbon) bonds with CO2 gathered from the air bonds to make a 6C molecule. The 6C molecule is then broken down into 3C molecules.
STEP 2: The energy from ATP and NADPH energizes the 3C molecules.
STEP 3: Some 3C molecules will bond or leave the cycle to make sugars, glucose and other compounds. The rest of the 3C molecules are changed back into 5C molecules from the energy in the ATP. The remaining 5C molecules are then repeated in this process, making more glucose!
SUMMARY: CO2, ATP AND NADPH CREATE GLUCOSE
ALSO KNOWN AS CALVIN CYCLE BECAUSE CALVIN DISCOVERED THIS PROCESS.
STAGE 1: LIGHT DEPENDANT REACTIONS
LOCATION: THYLAKOIDS
The light dependant reaction needs light absorbing pigments to take place. Using the light energy from the sun, electrons and hydrogen ions from water, ATP and NADPH is created. Oxygen (O2) is also created as a waste product from these reactions. This process occurs in photosystems (PS)
STEP 1: Chlorophyll pigments in PSII absorbs photons from the sunlight which transfers energy into the electrons causing them to become excited. Thylakoid membranes become negatively charged. An electron transport chain starts, actions take place in step 2.
STEP 2: H+ goes into the thylakoids. Enzymes break apart water compounds and separate them into hydrogen molecules and oxygen molecules. Water electrons replenish the photosystem all while oxygen molecules bond in pairs (O2) and is released as a waste product.
STEP 3: Electron transport chain becomes longer as chlorophyll in photosystem 1 absorbs sunlight which excites electrons. In the stroma just outside the thylakoid, electrons help bond NADP+ and the hydrogen ion (H+) into NAPDPH. This molecule will be really important and will be used later in the light independent reaction. NAPDH also acts as a hydrogen carrier.
STEP 4: The abundance of hydrogen that was broken down because of the presence of water diffuses into stroma. H+ helps bond ADP with another phosphorus atom to create ATP. ATP will also be used later in the light independent reaction.
SUMMARY: O2, ATP, NADPH ARE CREATED. THESE MATERIALS WILL BE USED TO CREATE GLUCOSE IN THE LIGHT INDEPENDENT REACTION
Brief structure of the chloroplast
ONLY FOUND IN PLANT CELLS