Transcript Chapter 8 PowerPoint
8-1 Energy & Life • All living things require energy • But what is it and where does it come from? Chemical Energy & ATP • Cells use adenosine triphosphate to store & release energy • Is like a fully charged battery • A phosphate can be + or - to store or release energy • It provides energy to work the sodium (Na) potassium (K) pump • It provides energy for movement • It powers the production of proteins and other molecules • It even helps fireflies glow! 8-2 Photosynthesis: An Overview • Plants use energy from the sun to convert water and carbon dioxide into carbohydrates (sugars & starches) and release oxygen as a waste product When a tiny seed grows into a tall plant where does its mass come from??? • In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule in chloroplasts. • Sunlight, which you perceive as white light, is actually a mixture of different wavelengths of light. • Your eyes see the different wavelengths of the spectrum as colors. • Chlorophyll does not absorb light well in the green region of the spectrum. • Green light is reflected by leaves, which is why plants look green. • Some of the light absorbed is converted directly to electrons in chlorophyll, raising the energy for photosynthesis. Inside a chloroplast Light Dependant Reactions • Reactions requiring light produce O2 and convert ADP and NADP+ into the energy carriers ATP & NADPH. • This reaction requires light. • It occurs in the thylakoid of a chloroplast. • Pigments in photosystem II absorbs light. • The absorbed light increases the energy of electrons. • Water is broken up into H+ and O2. • Oxygen is released into the air. • NADP+ picks up high energy electrons and H+ ions to produce NADPH. • The inside of the membrane fills with H+, making the outside negative. • The difference of charge provides energy to make ATP. The Calvin Cycle • ATP and NADPH are used from the light dependant reactions to produce highenergy sugars. • Melvin Calvin worked out the details for this light independent reaction. Occurs in stroma. • A. CO2 molecules combine with carbon molecules. The result is 12-3 carbon molecules. • Carbon molecules are converted into higher energy forms. • Where do you think this energy came from? • Some Carbon molecules are removed & used to produce sugars & other compounds. Factors affecting photosynthesis • Shortage of water can slow or stop the process. • Temperature should be between 0’c – 35’c since enzymes work best at those temperatures. • Light intensity can speed up the process up until a certain point.