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Chapter 8 Photosynthesis.notebook January 03, 2017 Chapter 8 Photosynthesis Section 81 Energy and Life Key Concepts Where do plants get the energy they need to produce food? What is the role of ATP in cellular activities? Why don't bushes or other trees usually grow underneath large trees? Living things need energy to survive. Energy the ability to do work If living things did not have the ability to obtain and use energy, life would not exist. Where does the energy that living things need come from? food Autotrophs auto self trophe food also called a self feeder plants and some unicellullar organisms autotrophs autotrophs make their own food through a process called photosynthesis Heterotrophs hetero other trophe food also called other feeder heterotrophs get there energy from the food they eat To live all organisms must release energy in sugars and other compounds. Energy comes in different forms light, heat, and electricity Energy can be stored in chemical compounds. Cells use a chemical compound to store and release energy is ATP = adenosine triphosphate contains adenine, 5carbon sugar (ribose), 3phosphate groups 3phosphate groups store and release energy lines between groups represent bonds Energy needed by an athlete comes from ATP Storing energy Adenosine diphosphate ADP just like ATP but short of a phosphate group living things store energy by adding a phosphate group as energy is available changing ADP to ATP When energy is needed, the bond between the second and third phosphate group is broken so energy can be released. What do cells do with this energy? Cells Use Energy carry out functions to survive synthesis of proteins and nucleic acids Releasing Energy breaks the chemical bonds between 2 and 3 phosphate group ATP basic energy source for all cells Most cells have only a small amount of ATP that will last for only a few seconds of activity. ATP is not good at storing large amounts of energy. However, they are very efficient at regenerating ATP from ADP as the cell needs it. It uses the energy in glucose to create the ATP. Dec 119:48 AM 1 Chapter 8 Photosynthesis.notebook January 03, 2017 82 Photosynthesis: An Overview Key Concepts What did the experiments of van Helmont, Priestly, and Ingenhousz review about how plants grow? What is the overall equation for photosynthesis? What is the role of light and chlorophyll in photosynthesis? Photosynthesis plants use the energy of sunlight to change H2O and CO2 to make sugars, starches, and O2. Discovery of Photosynthesis Jan van Helmont began study of photosynthesis in 1600's experimented with mass of plants where did plants get their mass from as they grew determined plants get mass from the H2O however at that time, he did not know that CO2 was part of the equation Joseph Priestly about 100 years later discovered that plants release O2 Jan Ingenhousz proved light was necessary for the production of O2 by the plant These 3 scientists contributed to beginning discoveries of what led to the discovery of photosynthesis. Other scientists used their work to make this discovery. Equation light 6CO2 + 6H2O C6H12O6 + 6O2 Photosythesis takes in carbon dioxide and water to make sugar and oxygen. Where do plants get each material needed for photosynthesis? CO2 from the air that mammals breath out enters through the stomata tiny openings in the leaf Water from the ground through the roots also minerals, brought through the xylem tissue that dies after one year, then new tissue develops Sunlight absorbed by pigments light absorbing molecules visible light UV light plants have pigments to protect themselves IR does not contain enough energy for photosyn. Chlorophyll pigment in the thylakoid membranes in the chloroplast Where do the products of photosynthesis go? O2 leaves plant cells through the stomata and goes into the atmosphere Glucose remain inside of cell and used to make sugars, starches, and cellulose (humans can not break down cellulose but needed for fiber) Phloem transports sugars down from the leaves to the cells, always alive Light and Pigment along with water and carbon dioxide, plants need light and chlorophyll plants gather light through pigments chlorophyll Two types of chlorophyll Chlorophyll a and Chlorophyll b these absorb light in different regions of the color spectrum when wave lengths are in the middle region of the sprectrum it is more difficult to absorb light plants reflect green light causes plants to look green In the fall, the pigments in leaves become visible since chlorophyll, the primary plant pigment, is not being made, so...it does not mask them. Review light is a form of energy, so any compound that absorbs light also absorbs energy from light. When chlorophyll absorbs light, much of the energy is transferred directly to the electrons in the chlorophyll molecule, raising the energy levels of these electrons, which makes photosynthesis work. http://chemistry.about.com/od/photosynthesis/l/blphotoquiz.htm Dec 159:11 AM 2 Chapter 8 Photosynthesis.notebook January 03, 2017 83 The Reactions of Photosynthesis Key Concepts What happens in the lightdependent reactions? What is the Calvin cycle? Chloroplast photosynthesis takes place inside the chloroplast in plants are leaves and in bacteria they are in the membrane Thylakoids inside chloroplasts sac like structure proteins in the thylakoids organize chlorophyll into clusters called photosystems (lightcollecting units) stacks of thylakoids granna single stack granum Stroma space outside the thylakoids Electron Carrier when light is absorbed by the chlorophyll, the electrons gain energy cells need a way to transport these highenergy electrons cells use an electron carriers electron transport chain molecules to transport highenergy electrons from chlorophyll to another molecule electron transport NADP+ nicotinamide adenine dinucleotide phosphate electron carrier transports electrons to parts of the cell accepts and hold 2 he electrons and a hydrogen ion (H+) which then converts NADP+ into NADPH this traps some energy from the sun in a chemical form NADP+ + 2e + H+ NADPH he electrons are used to build a variety of molecules the cell needs The Process of photosynthesis occurs in two stages that work together: LightDependent Reactions Photosystem II and I The first Photosystem is Photosystem II. It occurs before Photosystem I in the process, but was discovered after Photosystem I. takes place in the thylakoid membranes LightIndependent Reactions (Calvin Cycle) takes place in the stroma Photosystem lightcollecting units in a chloroplast Divided into two parts: LightDependent Reactions Figure 810 page 211 In the presence of light, the lightdependent reactions produce O2 gas and convert ADP and NADP+ into the energy carriers ATP and NADPH. Steps: 1. Begins when pigment in Photosystem II absorb light. 2. Light energy is absorbed by electrons, increasing energy. 3. These electrons come from water molecules. 4. Enzymes in the thylakoid membranes break apart the water molecule = 2 H+ ions and 1 oxygen atom. 5. The oxygen is released in the air. 6. The hydrogen ions are released into the thylakoid membrane. 7. He electrons move through the electron transport chain from Photosystem II to Photosystem I. 8. Energy from the electrons is used by the electron transport chain to transport H+ ions from the stroma to the thylakoid space. 9. Pigments in Photosystem I use energy from light to reenergize the electrons. 10. NADP+ picks up the he electrons and H+ ions which becomes NADPH. 11. As electrons are passed to NADP+, H+ ions are pumped across the membranes which causes a + charge on the inside and a charge on the membrane. This difference in charges provides the energy to make ATP. 12. H+ ions can not pass through the membrane on their own. ATP synthase a protein to help H+ ions across by allowing them to pass through it. The protein rotates to bind ADP and a phosphate group together. 13. This produces ATP for energy needed to create sugars. In Summary of the lightdependent reactions: USES PRODUCES Sunlight Helps with all ADP ATP NADP+ NADPH H 2O O2 Lightindependent Reaction (Calvin Cycle) The Calvin cycle uses ATP and NADPH from light dependent reactions to produce highenergy sugar that can be stored for a long time. The Calvin cycle does not require light, so called lightindependent rxns. Steps: 1. 6 Carbon Dioxide molecules enter the cycle from the atmosphere. 2. 6 Carbon Dioxide molecules bond with six 5Carbon molecules = 12 3Carbon molecules. 3. Energy from ATP and NADPH are used to convert the 12 3Carbon molecules into he forms. 4. Two of the 12 3Carbon molecules are removed from the cycle. They are then used to produce sugar, lipids, amino acids, and other compounds for plant metabolism and growth. 5. The remaining 10 3Carbon molecules are converted back into six 5Carbon molecules. These combine with 6 new carbon dioxides to begin the next cycle. USES ATP PRODUCES ADP NADPH NADP+ CO2 C6H12O6 The Calvin cycle uses six carbon dioxide molecules to produce a single 6carbon sugar. As photosynthesis goes in the Calvin cycle the process continuously removes carbon dioxide from the atmosphere. The plant uses the sugars for its energy needs and to build cellulose for growth and development What affects Photosynthesis? water temp light Use this website to review photosynthesis http://www.sciencegeek.net/Biology/review/U2PhotoFillin.htm Dec 169:00 AM 3
