Photosynthesis Chapter 8

Without the ability to obtain and use energy, life would cease to exist

Autotrophs and Heterotrophs Plants and other types of organisms are able to use light energy from the sun to produce food. Other animals such as heterotrophs obtain energy directly by eating other animals or the plants themselves.

Chemical energy and ATP Adenosine Triphosphate: principal chemical compounds that cells use to store and release energy. Consists of adenine, a 5- carbon sugar called ribose, and three phosphate groups

Energy Storage Adenosine Diphosphate (ADP) compound looks almost like ATP except that it has two phosphate groups instead of three. Store ADP and adds a phosphate group to it when needed = ATP

Releasing Energy Breaking the chemical bond between the second and third phosphates, it is released Has enough energy to power a variety of cellular activities including active transport, protein synthesis, and muscle contraction

Figure 8-3 Comparison of ADP and ATP to a Battery Section 8-1 ADP ATP Energy Energy Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP) Partially charged battery Fully charged battery

Van Helmont’s Experiment Devised an experiment to find out if plants grew by taking material out of the soil. Determined the mass of a pot of dry soil and a small seedling Then planted it Mass of the soil was unchanged Concluded: mass came from water

Priestley's Experiment Took a candle, placed a glass jar over it and watched as the flame gradually died out Found out if he placed a live sprig of mint under the jar and allowed a few days to pass, the candle could be relighted and would remain lighted for a while Mint plant had produced the substance required for burning

Jan Ingenhousz showed that the effect observed by Priestley occurred only when the plant was exposed to light.

Photosynthesis Equation 6CO2+ 6H2O --C6H12O6 + 6O2 Uses the energy of sunlight to convert water and carbon dioxide into high- energy sugars and oxygen

CO2 + H2O Sugars + O2 Photosynthesis: Reactants and Products Section 8-2 Light Energy Chloroplast CO2 + H2O Sugars + O2

Light and Pigments Requires light and chlorophyll Sunlight is a mixture of different wavelengths of light Visible spectrum: wavelengths that are visible to your eyes Pigments: light absorbing molecules Two main types of chlorophyll Chlorophyll a and chlorophyll b

Chlorophyll Absorbs light well in the blue- violet region and red regions Does not absorb light well in the green region of the spectrum Also contain red and orange pigments such as carotene

Inside a Chloroplast Thylakoids: saclike photosynthetic membranes Stroma: liquid region outside the thylakoid membrane Reactions have two parts: light dependent light independent

Electron Transport NADP+: accepts and holds 2 high energy electrons Converts NADP+ to NADPH

Light Dependent Reactions Require light produces ATP and NADPH

Process Chlorophyll absorbs light. Light energy is absorbed by electrons, increasing energy level Water is split into two H+ and Oxygen is released into the air NADP+ carries Hydrogen into the Calvin cycle ATP is made

Light Independent Reaction Calvin Cycle: uses ATP and NADPH from the light-dependent reactions to produce high-energy sugars Does not require light

Process carbon dioxide molecules enter the cycle from the atmosphere Carbon molecules are then converted into higher-energy forms called glucose ATP used 2 of the carbon molecules are removed from the cycle for use in the plant

5. the remaining carbon molecules are cycled back to start the next cycle