Transcript
Photosynthesis
Lauren Dever, Madison DevineLauren Kissel, and Anna Moloney
PHOTOSYNTHESIS
• The conversion of light energy to chemical energy
• Stored in glucose or other organic compounds
• Occurs in plants, algae, and other prokaryotes
PHOTOSYNTHESIS
• Photosynthesis involves the conversion of light energy into chemical energy.
• The process uses light energy and simple inorganic substances such as CO2 and H2O to produce organic compounds
PHOTOSYNTHESIS
• Light from the sun is composed of a range of wavelengths (colors)
• Plants are photoautotrophs, organisms that use light as a source of energy to synthesize organic substances
PHOTOSYNTHESIS
• Pigments that absorb all colors except blue appear blue because his part of the sunlight is not absorbed
• The blue light is reflected and can pass into our eye, to be perceived by cells in the retina
• A white or transparent substance does not absorb visible light
• Pigments that absorb all of the light appear black
PHOTOSYNTHESIS
• Photosynthesis is only able to occur in wavelengths that chlorophyll can absorb
• Shorter wavelengths have more energy, this leads to higher rates of photosynthesis
• Medium wavelengths (green) have the lowest rate of photosynthesis
PHOTOSYNTHESIS
• Chlorophyll is the main photosynthetic pigment• Chlorophyll is the green pigment located within chloroplasts
PHOTOSYNTHESIS
• ATP and hydrogen are used to fix carbon dioxide to make organic molecules
• The conversion of carbon dioxide into solid or liquid carbon compounds is called carbon fixation
PHOTOSYNTHESIS
• The three limiting factors of photosynthesis are light intensity, temperature, and carbon dioxide concentration
• They can all affect the rate at which a plant goes through photosynthesis if they are below the optimal level
• There is only one limiting factor at a time and they change throughout the process of photosynthesis
The Effect of Temperature
The Intensity of Light
The Effect of Carbon Dioxide Concentration
PHOTOSYNTHESIS
• The various structures in the chloroplast are highly visible in this electron micrograph image• This is where photosynthesis occurs
PHOTOSYNTHESIS
• Chloroplasts have such characteristics as– A double membrane called the chloroplast
envelope– A complex system of internal membranes
known as thylakoids– Small spaces of fluid inside the thylakoids– Fluid surrounding the thylakoids known as
stroma
PHOTOSYNTHESIS
• Photosynthesis consists of two different parts of reactions, light- dependent and light- independent
• Light- dependent reactions involve the production of ATP
• Light- independent reactions involve the production of glucose, known as the Calvin cycle
• However, they are a result of the light- dependent reactions so they are indirectly dependent on light
PHOTOSYNTHESIS
• Light energy is used to produce ATP and to split water molecules (photolysis) to form oxygen and hydrogen- The light energy is absorbed by chlorophyll
• Light- dependent reactions produce ATP by means of photophosphorylation
• The light absorbed takes the form of electrons in the thylakoids
PHOTOSYNTHESIS
• The process begins in Photosystem II, it then proceeds to the electron transport carrier, and then to the ATP synthase
• A proton concentration gradient forms in the thylakoid membrane helping to create ATP
• In cell respiration, this is known as chemiosmosis
PHOTOSYNTHESIS
• Photosystem I produces NADPH which is used in the light- independent reactions
• The chlorophyll absorb light and raise one electron to a high energy level, called photoactivation
• The electron is connected to the electron chain from Photosystem II and used to reduce NADP+
• Cyclic photophosphorylation
PHOTOSYNTHESIS
PHOTOSYNTHESIS
• Carbon fixation and carbohydrate synthesis are light- independent reactions, these are known as the Calvin cycle
• Carbon fixation produces glycerate- 3- phosphate, a three- carbon compound
• The carbon dioxide mixes with ribulose biphosphate, a 5- carbon compound to create glycerate- 3- phosphate
PHOTOSYNTHESIS
• For a carbohydrate to be produced, hydrogen has to be added to the glycerate- 3- compound, ATP and NADPH are needed for this to occur
• The result of this reaction is a three- carbon sugar called triose phosphate
• The triose phosphate is used to regenerate RuBP
• This cycle is called the Calvin cycle
BIBLIOGRAPHY
• http://science.hq.nasa.gov/kids/imagers/ems/roygbiv_waves.gif
• http://www.agri.huji.ac.il/~zacha/images/chloroplast.jpg
• http://www.microscopy.fsu.edu/cells/chloroplasts/images/chloroplastsfigure1.jpg
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