8-1 Energy & Life All living things require energyAll living things require energy But what is it and where does it come from?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 batteryIs like a fully charged battery A phosphate can be + or - to store or release energyA phosphate can be + or - to store or release energy

It provides energy to work the sodium (Na) potassium (K) pumpIt provides energy to work the sodium (Na) potassium (K) pump It provides energy for movementIt provides energy for movement It powers the production of proteins and other moleculesIt powers the production of proteins and other molecules It even helps fireflies glow!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.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.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.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 high- energy 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.