Chapter 9 Energy in a Cell—Overall Objectives Describe the Light and Dark stages of photosynthesis Light Spectrum; V.L.S.; ROYGBIV; why is chlorophyll green; Know order, which end of VLS is higher energy and shorter wavelength. Why organisms need energy. Know general formula for photosynthesis What is ATP?

9.1:THE NEED FOR ENERGY

Energy Needs Necessary for work Kinds of work your body does: mechanical chemical electrochemical shuttling

Where the energy comes from Stored in chemical bonds Convert the food we eat Into: –ATP A form of stored energy Short-term energy storage “the energy currency of the cell”

Energy Sources The main sources of ATP are the major energy reactions of: photosynthesis and cellular respiration

ATP –Energy Currency

Energy Relationships ATP BIOSYNTHETIC PATHWAYS (ANABOLIC) ENERGY INPUT DEGRADATIVE PATHWAYS (CATABOLIC) energy-poor products (such as carbon dioxide, water) large energy-rich molecules (fats, complex carbohydrates, proteins, nucleic acids) simple organic compounds (simple sugars, amino acids, fatty acids, nucleotides) ADP + P i

Energy Flow in the Living World All living org. need energy. Get energy from breaking down food. Photosynthesis: Light energy used to build sugars and other organic molecules from inorganic molecules. Plants, Algae (protists), some Bacteria. Cellular Respiration—releases energy

Photosynthesis Summary Equation 6H 2 O + 6CO 2 6O 2 + C 6 H 12 O 6 watercarbon dioxide oxygenglucose LIGHT ENERGY

Photosynthesis: Two main Stages 1. Light-Dependent Reactions Capture sunlight energy Use energy to make ATP and NADPH. 2 Light Independent Reactions – Build Carbohydrates IN PLANTS-THE WHOLE PRODUCTION TAKES PLACE IN THE CHLOROPLASTS

The chloroplasts and pigments

Photosynthesis:Light Light is a form of energy from the sun Electromagnetic Spectrum-all the wavelengths of light Visible Light Spectrum-a portion-we can see— Photosynthesis All butGreen&YellowUsed Shorter=more energy

Light Spectrum Rainbow

The V.L.S. Wavelength : Shorter Longer Energy: More Less

. Pigments-absorb light in V.L.S. Chlorophyll-main pigment Carotenoids—help out

Pigments Absorb certain wavelengths Color you see are the wavelengths NOT absorbed A few absorb so many, they appear dark or black Wavelength (nanometers) chlorophyll b chlorophyll a

PHOTOSNYTHESIS PROCESS OVERALL Light Reactions: Chlorophyll molecules in Thylakoid absorb light energy, energizing electrons; electrons are lost and used to drive the synthesis of ATP. –Water donates electrons and hydrogens. NADPH forms. Dark Reactions: The ATP and NADPH along with CO2 are used (in the dark) to make sugar in the stroma in the Calvin Cycle.

Light-Dependent Reactions Light strikes the chlorophyll molecules in the thylakoid membrane in this organelle,_______________; energy is transferred to the chlorophyll electrons. The “excited” electrons jump off chlorophyll !!! This energy induces Photolysis—splitting of ____________, and electrons from water replace the electrons lost by chlorophyll. The electrons pass through 2 different Electron Transport Chains (each is a chain of proteins embedded in the thylakoid membrane). Some of the electron’s energy is used to pump H+ into the center of the Thylakoid disc.—the inside of the thylakoid. A the end of the road (I mean chains), the electrons are transferred to an electron carrier: NADP + along with 2 electrons and an H + (from the water) forming NADPH.

Continued:Make ATP and NADPH Some of the electron’s energy is used to pump H+ into the center of the Thylakoid disc—the center of the thylakoid---getting VERY FULL OF H+. H+ H+ H+ H+ H+ H+ ADP + P ATP Then the H+ H+ H+ diffuse out—into the Stroma. The energy from this flow drives assembly of ATP from ADP and P (CHEMIOSMOSIS). A the end of the road (I mean chains), the electrons are transferred to an electron carrier, NADP +, along with 2 electrons and an H+ (from the water) forming NADPH. Take a deep breath—now answer this question: What happens to the O2 that was Part of the water that split??? Review Stage 1 –___________???major pigment in plants –Which portions of the VLS does not absorb? –SOOOO Why does it look green??? –What other pigment helps too?

More review--- Explain why leaves turn color in the fall??—take a minute to answer this in your notes.

The Sugar initially produced is used by the plant to make other organic compounds. Plants will use the sugars made to FUEL their metabolic activities too!!