Photosynthesis – what you really need to know…

Warm Up #1 Give an example of an autotroph. List 2 examples of a heterotroph. Where is the energy stored in an ATP molecule? What’s wrong with ATP’s energy storing capabilities?

Warm Up #2 Write the chemical equation for photosynthesis. What are the reactants? What are the products? Where do the reactants come from? 5. What is the pigment found in plants that give them their green color?

Warm Up #3 Name the two cycles of photosynthesis. Is light required for the light reactions? Is light required for the Calvin Cycle? Can the Calvin cycle work if light is present?

Energy and Life Autotroph – organisms that are able to make their own food (plants) Heterotroph – organisms that must obtain energy from food they consume.

Energy in Living Systems Energy flows through living systems. You get energy from the food you eat – where does the energy in the food come from? Energy flows from autotrophs ( organisms that make their own food) to heterotrophs (organisms that rely on others for food).

ATP The ultimate source of most energy found on Earth is the sun. In living things, energy is stored in cells in the mitochondria in the form of ATP (adenosine triphosphate) ATP has three phosphates – the key to it’s ability to store and release energy lies in the bonds between the phosphates. mitochondrion

ATP Molecule

Energy stored in the cell is released gradually in a series of enzyme (protein) assisted reactions. Energy is stored temporarily in molecules of ATP. Released energy is enough to process most of the cell’s activities.

Storing and Releasing Energy ADP Adenosine diphosphate – looks like ATP but only has 2 phosphates This small difference is the key to the energy storing capabilities – ADP adds a phosphate and becomes ATP ( a fully charged battery)

Energy is released when the bonds between 2nd and 3rd phosphates are broken!

PHOTOSYNTHESIS Literally means “put together with light” Process by which light energy (energy from the sun) is converted into chemical energy (energy we need to survive). Almost all autotrophs, especially plants are photosynthetic organisms.

EQUATION 6CO2 + 6H2O C6H12O6 +6O2 Reactants Products Light 6CO2 + 6H2O C6H12O6 +6O2 Reactants Products Carbon Dioxide Glucose (sugar-starch) Comes from the atmosphere, Into the leaves through the stomata Water Oxygen Comes from the soil

Requirements for Photosynthesis In order for photosynthesis to occur 4 things must be present: 1. Carbon Dioxide 2. Water 3. Light 4. Chlorophyll – plants principal pigment – gives it a green color. Light is a form of energy – any compound that absorbs light – stores energy

Chloroplast: Site of Photosynthesis

Steps of Photosynthesis LIGHT DEPENDENT – requires light to split water molecules producing Oxygen, ATP and NADPH

2. CALVIN CYCLE – does NOT require light, uses Carbon Dioxide (from the atmosphere) , ATP and NADPH to make glucose (simple sugar)

Factors affecting photosynthesis… Temperature – not as much photosynthesis in the winter months because the sun’s rays are not as strong. Intensity of Light – the more intense the light the more photosynthesis and vice versa Water & Carbon dioxide availability

Why do leaves change color in the fall? During winter, there is not enough light or water for photosynthesis. The trees will rest, and live off the food they stored during the summer. They begin to shut down their food-making factories. The green chlorophyll disappears from the leaves. As the bright green fades away, we begin to see yellow and orange colors. Small amounts of these colors have been in the leaves all along. We just can't see them in the summer, because they are covered up by the green chlorophyll.

The bright reds and purples we see in leaves are made mostly in the fall. In some trees, like maples, glucose is trapped in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn cause the leaves turn this glucose into a red color. The brown color of trees like oaks is made from wastes left in the leaves.

occurs in the mitochondria, yields more ATP . Cellular Respiration 2 types: 1. Aerobic – requires occurs in the mitochondria, yields more ATP . 2. Anaerobic – does not require oxygen, yields less ATP.

Cellular Respiration C6H12O6 + 6O2 6CO2 + 6H2O This equation is the exact same as the equation for photosynthesis, except..? It is reversed!

Cellular Respiration 3 Stages of AEROBIC RESPIRATION 1. Glycolysis – “sugar splitting” glucose (sugar) is broken down in the cytoplasm. Yields 2 ATP, occurs in cytoplasm. DOES NOT REQUIRE OXYGEN. If no oxygen is present the cycle stops here. Occurs in all organisms – heterotrophs and autotrophs.

2 and 3: Krebs Cycle and Electron Transport Chain Beginning of aerobic respiration Requires oxygen Takes place in the mitochondria ADP is converted to ATP. The two cycles together produce 34 ATP. The total of all three parts = 36 ATP

Cellular Respiration ANAEROBIC RESPIRATION- when you work out too much or get physically tired, your cells do not get enough oxygen. This causes them to go through a process called fermentation.

2 Types of Fermentation Lactic acid fermentation - in cytoplasm 2. Alcoholic - in yeast cells

Lactic acid fermentation – occurs in animals, lactic acid is what makes your muscles burn, leads to cramping. Reason you pant after exercise because your cells are lacking enough oxygen to go through aerobic respiration.

2. Alcoholic Fermentation – process by which beer and wine are made. Yeast do this!

Comparing photosynthesis and cellular respiration Uses water Gives off water Uses carbon dioxide Gives off carbon dioxide Makes glucose Breaks down glucose Gives off oxygen Uses oxygen Takes in energy from the sun Releases energy Occurs in chloroplast Occurs in mitochondria Occurs in plants, some bacteria and protists Occurs in all organisms