Photosynthesis Chapter 8

Section 8.1 Energy and life

Chemical energy and atp What is energy? - The ability to do work What are some uses of energy? - build new molecules - contract muscles - carry out active transport Life depends on the ability to obtain and use energy

Chemical energy and atp What are some forms of energy? - light, heat, and electricity Energy can be stored in chemical bonds (ex. Wax melting. Explain example in class- write down). When energy is lost, it is released as heat

Chemical energy and atp Living things use chemical fuels to store and release energy, such as: - adenosine triphosphate (ATP), which is used by cells. ATP composition (make up) - adenine - 5-carbon sugar (ribose) - three phosphate groups ( key to storing and releasing energy)

Storing energy What do cells use to store energy? - Adenosine diphosphate (ADP) - ADP has two phosphate groups instead of three like ATP. How? - When cells have energy available, it can store small amounts by adding phosphate groups to the ADP molecule, making ATP.

releasing energy How is energy released in cells? - By breaking the bonds in ATP between the second and third phosphate groups. ATP can release and store energy by breaking and re-forming the bonds between its phosphate groups, which makes ATP useful energy source for all cells.

Biochemical energy How do cells use ATP energy? - carry out active transport Process Cell membranes have a sodium-potassium pump. Membrane proteins pump sodium ions (NA+) out of the cell. Potassium is pumped into the cell. ATP provides the energy (E) that helps the membrane maintain homeostasis (balance). ATP energy also provides E for cilia and flagella to function. Synthesis of proteins (making of proteins)

Biochemical energy How much ATP is in cells? - small amounts - enough for cells to use for activity (seconds only) Is ATP good for storing large amounts of energy over a Long period of time? - no How can cells keep ATP for a source of energy? - by regenerating ATP from ADP as needed by using food like glucose.

Heterotrophs and autotrophs Cells do not automatically supply ATP. They must get ATP from a source, but what sources? Heterotrophs Autotrophs Photosynthesis Organisms that obtain food by consuming (eating) other living things Organisms that make their own food. How autotrophs use the energy of sunlight to produce high-energy carbohydrates, sugars and starches that can be used as food. Humans, animals Plants, algae, bacteria Plants convert energy from the sun into chemical energy stored in the bonds of carbohydrates

Chloraphyll and chloroplasts In order for photosynthesis to occur, light from the sun must be captured. LIGHT 1. How does energy from the sun travel to earth? - In the form of light 2. What is light made of? - a mixture of wavelengths - we see wavelengths in a spectrum 3. Wavelength spectrum can be viewed in several colors - red, orange, yellow, green, blue, indigo, and violet

Chlorophyll and chloroplast PIGMENT 4. How do plants gather the sun’s energy? - they use PIGMENTS (photosynthetic organisms use pigments for sunlight energy absorption) 5. What is a pigment? - light absorbing molecule 6. What is the plants principal(main) pigment? - CHLOROPHYLL 7. There are two (2) types of chlorophyll - chlorophyll a and b - both absorb light best in the blue-violet, and red spectrum regions, and worst in the green spectrum.

Chlorophyll and chloroplast PIGMENT 8. What makes plants look green? - the reflection of green light by leaves. 9. What other pigments do plants have? - CAROTENE ( an accessory pigment), which is a red and orange pigment - carotene absorbs light in the other regions of the spectrum 10. When temperature falls, the chlorophyll breaks down, leaving the red and orange pigments visible (Why leaves are red and orange during the fall)

Chlorophyll and chloroplast CHLOROPLASTS 11. Photosynthesis takes place inside the chloroplast 12. What are the parts of the chloroplast? - THYLAKOIDS = saclike photosynthetic membranes that are interconnected and arranged In stacks. - The stacks of thlylakoids are called GRANA - CHLOROPHYLL pigments are located inside the thylakoids - STROMA= the fluid portion of the chloroplast

Chlorophyll and chloroplast ENERGY AND COLLECTION 13. Why is chlorophyll so important? a. chlorophyll absorbs light very well. b. large portions of the light absorbed is transferred to electrons (located in the chlorophyll). c. high-energy is made by increasing the energy levels of the electrons , which make photosynthesis possible. Sunlight absorbed Electrons high energy electrons Photosynthesis

High energy electrons NADP+ 14. How do plants carry high-energy electrons from the chlorophyll to other molecules in the plant? - they use electron carrier molecules * Electron carriers can accept a pair of high-energy electrons and transfer them, along with most of their energy to other molecules* 15. NADP+ (nicotinamide adenine dinucleotide phosphate) is a carrier molecule

High energy electrons NADP+ 16. What is the process of NADP+? A. accepts/holds 2 high-energy electrons + Hydrogen ion (H+) B. Converts NADP+ NADPH (traps energy in chemical form) C. NADPH carries high-energy electrons (produce in chlorophyll) to chemical reactions in the cell

photosynthesis 17. What is photosynthesis? - the process of plants using energy from the sunlight to convert water and carbon dioxide (reactants) into high- energy sugars and oxygen (products) 18. The plant uses the sugars to produce: carbohydrates (starches) provide energy to make proteins and lipids 19. What is the chemical reaction for photosynthesis 6CO2 + 6H2O C6H12O6 + 6O2 (REACTANTS) (PRODUCTS) 6 Carbon Dioxide + 6 Water Sugar + 6 Oxygen

photosynthesis There are two steps in the process of photosynthesis. LIGHT –DEPENDENT REACTION a. This is the first set of reactions. b. Requires direct light, and pigments c. Uses sunlight's energy to make ATP d. Reaction takes place within the Thylakoids e. Water is required (source of electrons), and Hydrogen ions (H+) f. The gas released as a byproduct is OXYGEN

LIGHT –INDEPENDENT REACTION photosynthesis LIGHT –INDEPENDENT REACTION Plants absorb CO2 from the atmosphere to complete photosynthesis and produce carbon-containing sugars and other carbohydrates Process ATP and NADPH molecules produce high-energy sugars from carbon dioxide (CO2) and water H2O. No light is required. Reaction takes place in the stroma (fluid portion of the chloroplasts). Known as the Calvin Cycle

Section 8.3 the process of photosynthesis

Light –dependent Reactions Four (4) steps in light dependent reaction - photosystem II - Electron Transport Chain - photosystems I - ATP formation

Light –dependent Reactions The Light-Dependent reactions use energy from the SUN to produce: 1. OXYGEN 2. Convert ADP ATP Convert NADP+ NADPH 3. What are the proteins in Thylakoids called? PHOTOSYSTEMS 4. Photosystems are surrounded by accessory pigments.

Light –dependent Reactions PHOTOSYSTEMS 5. What is the purpose of a photosystem? Absorb sunlight and generate high-energy electrons. 6. There are two photosystems called PHOTOSYSTEM I AND PHOTOSYSTEM II

Light –dependent Reactions PHOTOSYSTEM II 7. Light Energy is absorbed turns into high-energy electrons 8. Water molecules are split and replace the electrons 9. H+ ions and oxygen is released

Light –dependent Reactions ELECTRON TRANSPORT CHAIN 10. High energy electrons move down the (ETC) to the PHOTOSYSTEM I. 11. The energy generated (made) is used to pump H+ ions across and into the thylakoid membranes.

Light –dependent Reactions PHOTOSYSTEM I 12. Electrons are reenergized 13. A second electron transport chain transfers the reenergized electrons to NADP+ making NADPH

Light –dependent Reactions ATP Formation 14. Thylakoid membrane become positively (+) charged (as a result of the H+ ions). 16. ATP Synthase - Pass H+ ions back across the thylakoid membrane - Converts ADP ATP

Light –independent Reactions Processes of Light- Independent Reactions the CALVIN CYCLE - Carbon Dioxide - Sugar Production

Light –independent Reactions During the light-independent reaction (Calvin Cycle), ATP and NADPH from the light-dependent reactions produce high-energy sugars

Light –independent Reactions CARBON DIOXIDE CO2 enter the Calvin Cycle from the atmosphere. 6 CO2 molecules (atmosphere)+ 5-carbon compounds (inside chloroplast) 3-carbon compounds produce For every 6 CO2 molecules that enter the cycle = twelve 3- carbon compounds are produced. Energy from ATP and NADPH convert the carbon compounds into HIGHER ENERGY

Light –independent Reactions SUGAR PRODUCTION Two of the twelve (12) 3-carbon molecules are removed. The two 3-carbon molecules are used by the plant to produce: - sugars - lipids - amino acids 3. The remaining ten (10) 3-carbon molecules back to 5- carbon molecules

Light –independent Reactions SUGAR PRODUCTION

Light –independent Reactions CALVIN CYCLE SUMMARY Energy for the reactions comes from the light-dependent reaction. 6CO2 makes--------- 6 carbon sugar The sugars are used for energy, growth and development by the plant Make lipids, proteins, carbohydrates (cellulose)

Light –independent Reactions RESULTS Light-dependent reaction – traps the ENERGY from the SUNLIGHT in what form? - CHEMICAL FORM 2. Light-independent reaction – uses CHEMICAL ENERGY to make : - high –energy sugars - water

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