General Terms

• Photons are packets of energy, which is the fundamental unit of light. The intensity of light depends on the number of photons absorbed per unit of time
• Wavelength is the total distance moved by the photon during one vibration
• the energy of a photon is called a quantum, and is inversely proportional to the wavelength of the light: the longer the wavelength, the lower the energy of photon
• Sunlight consists of about 4% ultraviolet radiation, 52% infrared radiation and 44% visible light
• Ultraviolet radiation contains too much energy because of its high-energy photons, thus it breaks bonding in the molecules that causes sunburns
• Infrared radiation does not contain enough energy per photon to be useful to living systems
• Visible light contains the right amount of energy for biological reaction such as the photosynthesis, by having it absorbed by pigments
• Pigments are molecules that absorb light and give the color of the object.
• Back pigments absorb all wavelengths of light
• white pigment absorb no wavelength of light
• Chlorophyll are hydrophobic pigments that occurs in plants and algae. It absorbs red and blue light and reflects green light
• Chlorophyll a is a grass-green pigment whose structure includes an atom of magnesium
• Chlorophyll b is a bluish-green pigment found in chloroplasts, green algae and plants
• Carotenoids are accessory pigments that occur in all photosynthetic organisms, they absorb light that cannot be absorbed by chlorophyll a. They also protect the plant from photooxidation that kills pant
• Photooxidation is the oxidation reaction happening in the presence of light energy. When high-intensity light hits plant, there is an excitation of energy that leads to oxidation process. The accumulation of reactive oxygen harms the plant
• When pigments absorb light, the energy can be released as heat and light. The process where it releases light is via fluorescence.
• Photosystems are functional units for photosynthesis, whose work is the absorption and transfer of light energy, which implies transfer of electrons
• Photosystem I is a type of photosystem where it absorbs light of longer wavelengths that are greater than 680nm
• Photosystem II is a type of photosystem that absorbs wavelength in a shorter distance, less than 680nm
• Photo means light and synthesis means to build
• stomata is the tiny opening of the leaf, where carbon dioxide enters and oxygen leaves
• Lumen is the fluid inside the thylakoid
• Photosynthesis can be broken down into two stages: Light dependent reactions and the Calvin cycle
• The light dependent reaction in photosynthesis occur inside the thylakoid within the chloroplast, while the Calvin cycle occurs in the stroma
• The light dependent reaction oxidizes water into oxygen gas, and NADP+ picks up those electrons and reduce it to NADPH
• In the light dependent reaction, it requires light energy. Some of it is used to make ATP from ADP and Pi, using the process of chemiosmosis with the presence of the enzyme ATP synthase
• The products in the light-dependent reactions are ATP, NADPH, and oxygen gas
• Calvin Cycle does not require light, but it does require Carbon Dioxide, ATP and NADPH to form a glucose molecule, NADP+ and ADP and Pi
• Photosystem II is the one that coverts water into oxygen gas in the light-dependent reaction
• The Calvin Cycle can be broken down by three parts: Fixation of CO2, Reduction of PGA to G3P and the Regeneration of RuBP from G3P
• Fixation of CO2 involves the use of an enzyme called Rubisco which catalyses the formation of unstable compound called Phosphoglycerate (PGA)
• G3P Dehydrogenase is an enzyme that catalyzes NADPH to NADP+, which will be able to get 6 molecules of G3P
• one molecule of G3P will be used to make glucose while the other 5 will be used to regenerate RuBP
• Carbon Fixation refers to the use of carbon dioxide into making more useful compounds within living organisms
• C3 plants will firstly generate a 3-carbon compound (3-PGA). It includes soybeans, oats, and wheat. However, when they are placed in dry places, they will undergo photorespiration, which there is no entrance for carbon dioxide
• C4 Photosynthesis is found in plants that live in hot, dry climates. CO2 if fixed into 4C compound, avoiding the entrance of photorespiration
• The C4 pathway involves two different types of cells - mesophyll cell and bundle sheath cell.
• In C4 photosynthesis, the Calvin cycle occurs inside the bundle sheath cells.
• C4 plants undergo photosynthesis by initially fixing carbon dioxide in the mesophyll cells
• PEP carboxylase is the enzyme that catalyzes CO2 and PEP(3C) to form oxaloacetate, which will release CO2 in the bundle sheath cells meaning the level of carbon there will be always high enough for Calvin Cycle to make sugars