Photosynthesis

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

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

Chemical Energy Candles burn Candles burn What does that mean? What does that mean? Wax molecules store energy in the bonds between the hydrogens and carbons Wax molecules store energy in the bonds between the hydrogens and carbons

Electrons move from higher energy levels to lower energy levels. Electrons move from higher energy levels to lower energy levels. Heat and light energy are released. Heat and light energy are released.

Living things use and store energy

Plants store energy as sugar or starch

Animals store energy as glycogen (animal starch)

Or as fat

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

Storing Energy ADP (adenosine diphosphate) is a compound that looks like ATP except it is lacking a __________ group. 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 energy. This one difference is the key to the way in which living things store 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. 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. 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?.... 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. 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 Active transport Protein synthesis Protein synthesis Muscle contraction Muscle contraction

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

Question????? Do you think cells have an abundant amount of ATP? Do you think cells have an abundant amount of ATP? Answer: Most cells have only a small amount of ATP, enough to last them for a few seconds of activity. Answer: Most cells have only a small amount of ATP, enough to last them for a few seconds of activity. Why? Why? Answer: ATP is great for transferring Energy, not for storing Energy. 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 Long term storage is done by other molecules, such as glucose, glycogen, starch ATP can be regenerated by the cell over and over again ATP can be regenerated by the cell over and over again ADP + Energy + P → ATP ADP + Energy + P → ATP Required energy comes from food molecules Required energy comes from food molecules

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

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

The Photosynthetic Equation

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

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

Parts of the chloroplasts Thylakoids-Proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters known as photosystems. Thylakoids-Proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters known as photosystems.

Photosystems-light collecting units Photosystems-light collecting units Reactions of photosystems in 2 parts: Reactions of photosystems in 2 parts: Light-dependent reactions (take place in thylakoid membrane) Light-dependent reactions (take place in thylakoid membrane) Light-independent reactions (take place in the stroma) Light-independent reactions (take place in the stroma) Parts of the chloroplasts

Light-Dependent Reactions The light-dependent reactions produce oxygen gas and convert ADP and NADP+ into ATP and NADPH. The light-dependent reactions produce oxygen gas and convert ADP and NADP+ into ATP and NADPH. Occur in the thylakoid 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. 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. 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 two sets of photosynthetic reactions work together… The light-dependent reactions trap the energy of sunlight in chemical form 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. 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 Shortage of water can slow down or stop photosynthesis Plants have adaptations to reduce water loss: waxy coating on plants in dry areas. Plants have adaptations to reduce water loss: waxy coating on plants in dry areas. Temperature Temperature Plants have enzymes that work best from degrees F. Temperatures above or below can damage these enzymes which can slow down or stop photosynthesis. Plants have enzymes that work best from degrees F. Temperatures above or below can damage these enzymes which can slow down or stop photosynthesis.

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