Vocabulary Grab a notebook page ADP ATP Autotroph Heterotroph Photosynthesis Chlorophyll Thylakoid Stroma Light Dependent Reaction Light Independent Reaction Photosystem Electron Transport Chain

Photosynthesis

Energy and Life Nearly every activity in modern society depends on Energy…think about it. Driving a car! Typing a paper! Using your IPOD! Using your cell phone! Living things also require ENERGY!

Where does that Energy come from? Autotrophs (AKA: Producers) Use the sunlight as their ENERGY source. Heterotrophs (AKA: Consumers) Obtain energy from the plants or other organisms that they consume.

Chemical Energy Candles burn What does that mean? Wax molecules store energy in the bonds between the hydrogens and carbons Candle burns by melting wax into wick, vaporizing wax molecules, breaking them apart releasing heat and light

When the candle is burning, electrons move from higher energy levels to lower energy levels. Heat and light energy are released.

Living things use and store energy Plants make sugars and starches Animals consume and then store sugars, starches and fats

Plants store energy as sugar or starch

Animals store energy as glycogen (animal starch)

Or as fat

ATP: Adenosine Triphosphate Adenine Ribose:5 carbon sugar 3 phosphate groups

Storing Energy ADP (adenosine diphosphate) is a compound that looks like ATP except it is lacking a __________ group. This one difference is the key to the way in which living things store & use energy. Phosphate

Storing Energy (cont.) When a cell has energy available, it can store small amounts of it by adding a phosphate group to ADP, producing ATP. Think of ATP as a fully charged battery and ADP as only a partially charged battery. Now that we have Energy stored…how do we release it?....

Releasing Energy Energy that is stored in ATP is released by breaking the chemical bond between the second and third phosphates.

What the energy in ATP can do Active transport Protein synthesis Muscle contraction

What the energy in ATP can do Synthesis of nucleic acids Move organelles throughout the cell Responds to chemical signals of cell Fireflies! (bioluminescence)

Question????? Do you think cells have an abundant amount of ATP? Why? Answer: Most cells have only a small amount of ATP, enough to last them for a few seconds of activity. Why? Answer: ATP is great for transferring Energy, not for storing Energy.

ATP Wrap-UP Long term storage is done by other molecules, such as glucose, glycogen, starch ATP can be regenerated by the cell over and over again ADP + Energy + P → ATP Required energy comes from food molecules

8-3: The Reactions of Photosynthesis Where does photosynthesis take place? Chloroplasts!

Parts of the chloroplast Thylakoids-Proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters known as photosystems. Granum – Stack of thylakoids Stroma – The fluid portion of the chloroplasts, outside the thylakoids

8-2:Overview of Photosynthesis Jan Van Helmont’s Experiment Plants gain mass from water Joseph Priestley Plants produce oxygen Jan Ingenhousz Light is necessary

8-2:Overview of Photosynthesis Photosynthesis converts light energy into the chemical energy of sugar and other organic compounds. Light energy drives the reactions O2- byproduct and is released into atmosphere

The Photosynthetic Equation

Light and Pigments Pigments: light absorbing molecules Chlorophyll absorbs blue-violet and red light When a pigment absorbs light, it absorbs the energy from that light Energy excites electrons

Light-Dependent Reactions The light-dependent reactions produce oxygen gas and convert ADP and NADP+ into ATP and NADPH. Occur in the thylakoid

Calvin Cycle (light-independent) The Calvin Cycle uses ATP and NADPH from the light-dependent reactions to produce high-energy sugars. It takes carbon dioxide from the atmosphere and converts it into high-energy sugars that can be used to meet the plant’s energy needs and to build more complex molecules.

What does all of that mean? The two sets of photosynthetic reactions work together… The light-dependent reactions trap the energy of sunlight in chemical form The light-independent (Calvin cycle) uses that chemical energy to produce stable, high-energy sugars from carbon dioxide and water.

Factors Affecting Photosynthesis Shortage of water can slow down or stop photosynthesis Plants have adaptations to reduce water loss: waxy coating on plants in dry areas. Temperature Plants have enzymes that work best from 32-95 degrees F. Temperatures above or below can damage these enzymes which can slow down or stop photosynthesis.

Factors Affecting Photosynthesis

Factors Affecting Photosynthesis Intensity of light Increasing light intensity increases the rate of photosynthesis. (It will reach a max level)

Factors Affecting Photosynthesis