Chapter 8.1: Energy and Life

Warm-Up 10/24/12 Where is energy stored in ATP? What are the reactants of photosynthesis? What are the products of photosynthesis? What is ATP used for within the body?

Sunlight is the main energy source for life on Earth.

Energy is the ability to do work! What is energy? Energy is the ability to do work!

Autotrophs (Producers) Capture energy from sunlight or chemicals and use that energy to produce food. Ex. Plants

Heterotrophs (Consumers) Organisms that rely on other organisms for their energy and food supply. Ex. Animals

Chemical Energy and ATP 1. Energy comes in many forms: a. Light b. Heat c. Chemical

1. Cells use chemical energy in the form of a chemical compound called ATP, or adenosine triphosphate. a. ATP contains: i. A 5-carbon sugar called ribose ii. A nitrogenous base called adenine iii. Three phosphate groups b. The bonds between the phosphate groups store and release energy

c. ATP is like a rechargable battery. ADP ATP Energy Energy Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP) Partially charged battery Fully charged battery

Chemical Energy and ATP: Storing Energy Energy is stored in ATP a. ADP, adenosine diphosphate, is similar to ATP but has two phosphate groups instead of three b. When a cell has energy available, it can store small amounts by adding a phosphate to ADP making ATP

Using the energy 1. When a chemical bond between the 2nd and 3rd phosphates of ATP is broken, energy is released

Chemical Energy and ATP: Releasing Energy 2. ATP has enough energy to power a variety of cellular activities A. active transport across the selectively permeable cell membrane B. protein synthesis C. muscle contractions D. Propels flagella E. Produces light in fireflies Firefly Escherichia coli bacterium with flagella

3. ATP is the basic energy source of all cells

ATP is a good short term energy storage that is recycled between ADP and ATP. Cells have only a small amount of ATP. 1. It is more efficient for cells to store energy as glucose. 2. When cells need energy they make ATP from ADP using energy from glucose.

ADP vs. ATP http://www.phschool.com/atschool/phbio/activities/cbd-3081/simbase.htm

C A B What is the name of the molecule above? What is the name of the part of the molecule labeled: A? ___________________________ B? ___________________________ C? ___________________________ adenine ribose 3 phospates

How does a cell get energy from this molecule? B How does a cell get energy from this molecule? By breaking the bond between the 2nd and 3rd phosphate. This releases the energy!!

Chapter 8-2 Photosynthesis: An Overview

What is photosynthesis? The process in which plants use the energy of the sun to convert water and carbon dioxide into high-energy carbohydrates (sugars and starches) and oxygen (a waste product).

The Photosynthesis Equation Plants obtain carbon dioxide from either the water or air they live in. Photosynthesis occurs in chloroplasts. The carbohydrates produced are 6-carbon sugars (C6H12O6). Chapter 8B Stop at 45 sec

Light Energy Chloroplast CO2 + H2O Sugars + O2

What does this equation look like when balanced? Carbon dioxide + water + light  sugars + oxygen CO2 + H2O + light  C6H12O6 + O2 What does this equation look like when balanced? 6 CO2 + 6H2O + light  1C6H12O6 + 6O2

Light and Pigments Photosynthesis requires: water carbon dioxide light chlorophyll (a pigment molecule in chloroplasts; two types) chlorophyll a chlorophyll b

Photosynthesis Needs… …and Light CO2 H2O

ROYGBIV Sunlight is perceived as white light, but is really a mixture of different wavelengths of light (like a rainbow). The visible light we can see is a very small portion of the electromagnetic spectrum. Red Orange Yellow Green Blue Indigo Violet Red: long wavelength, less energy Violet: Short wavelength, high energy

Pigments are molecules that absorb light at different wavelengths. Chlorophyll absorbs light in the visible spectrum, except the green wavelengths. Green light is reflected by the leaves, so plants look green. The high energy that is absorbed makes photosynthesis work.

Factors affecting photosynthesis Shortage of water Temperature (0-35 degrees Celsius) Intensity of light

Photosynthesis C6H12O6 O2 produces… for energy. produces… as a waste product.

Photosynethsis

Chapter 8-3: The Reactions of Photosynthesis

Inside a Chloroplast Photosynthesis takes place inside chloroplasts. Chloroplasts contain: thylakoids: saclike photosynthetic membranes containing pigments grana (singular: granum): stacks of thylakoids stroma: region of chloroplasts outside of the thylakoid membranes inner membrane outer membrane

Electron Carriers Sunlight excites electrons in chlorophyll, causing them to gain energy. An excited electron is like a hot coal, and cannot be easily carried from one place to another- a protein called an electron carrier is required to transport excited electrons.

NADP+ + 2 electrons + H +  NADPH Electron transport: An electron carrier molecule can accept a pair of high-energy electrons and transfer them to another molecule. Electron transport chain: Series of electron carriers Example: NADP+ (nicotinamide adenine dinucleotide phosphate) NADP+ + 2 electrons + H +  NADPH NADPH can carry high-energy electrons to other chemical reactions in the cell that need energy

Light Dependent Reactions The light-dependent reaction splits water, produce oxygen gas as waste, and converts ADP and NADP+ into ATP and NADPH.

Light Dependent Reactions Hydrogen Ion Movement Photosystem II ATP synthase Inner Thylakoid Space Thylakoid Membrane Stroma

Light Dependent Reactions Light hits Photosystem II in the thylakoid membranes. Two electrons are excited and these excited electrons are passed onto the electron transport chain To replace the lost electrons, the thylakoid membrane obtains low-energy electrons by splitting water 2H2O  4H+ + O2 + 2 e- The O2 is released as waste The hydrogen ions (4H+) are released inside the thylakoid membrane

Light Dependent Reactions Hydrogen Ion Movement Photosystem II ATP synthase Inner Thylakoid Space Thylakoid Membrane Stroma

Light Dependent Reactions Electron transport chain (ETC) Electrons are passed from Photosystem II to Photosystem I from one electron carrier to the next until they reach Photosystem I Energy from the electrons is used by the electron carriers in the ETC to force H+ ions from the stroma into the inner thylakoid space- build up of H+ will be used to drive ATP synthase

Light Dependent Reactions Hydrogen Ion Movement Photosystem II ATP synthase Inner Thylakoid Space Thylakoid Membrane Stroma

Light Dependent Reactions Light hits Photosystem I Pigments in Photosystem I use energy from light to energize two electrons, making them high-energy They are passed to NADP+ Reductase- catalyzes the reaction of NADP+ take combining with the high-energy electrons and hydrogen ions (H+) to become NADPH

Light Dependent Reactions Hydrogen Ion Movement Photosystem II ATP synthase Inner Thylakoid Space Thylakoid Membrane Stroma

Light Dependent Reactions Hydrogen Ion Movement The inside of the thylakoid membrane fills up with positively charged hydrogen ions (H+) as electrons are passed from Photosystem II to I ATP synthase The thylakoid membrane contains a protein called ATP synthase that spans the membrane and allows H+ ions to pass through it As H+ ions pass through ATP synthase, the protein rotates and binds ADP and a phosphate group to produce ATP.

Light Dependent Reactions Hydrogen Ion Movement Photosystem II ATP synthase Inner Thylakoid Space Thylakoid Membrane Stroma

Light-independent reactions (The Calvin Cycle) During the Calvin cycle, plants use ATP and NADPH from the light-dependent reactions to produce high-energy sugars for long-term storage. The Calvin cycle does not require light.

Thylakoids light CO2 H2O NADP+ ADP + P Calvin Cycle ATP NADPH Sugars Chloroplast Chloroplast NADP+ ADP + P Chloroplast Thylakoids Light- Dependent Reactions Calvin Cycle ATP NADPH

The Calvin Cycle There are four steps in the Calvin Cycle: CO2 enters the cycle Six carbon dioxide molecules enter and combine with six 5-Carbon molecules. Result: 12 3-carbon molecules

The Calvin Cycle Energy input The 12 3-carbon molecules are converted into high energy forms using ATP and NADPH During this process, 12 ATP  12 ADP During this process, 12 NADPH  12 NADP+

The Calvin Cycle 6-carbon sugar produced from two 3-carbon molecules removed to produce sugar 5-carbon molecules regenerated 10 remaining 3-carbon molecules converted into six 5-carbon molecules This requires 6 ATP  6 ADP These 5-carbon molecules can be reused in step A.

The Calvin Cycle CO2 Enters the Cycle Energy Input 5-Carbon Molecules Regenerated 6-Carbon Sugar Produced

Photosynthesis Light- dependent reactions Calvin cycle Thylakoid includes Light- dependent reactions Calvin cycle takes place in uses use take place in H2O and Energy from sunlight Thylakoid membranes NADPH and ATP Stroma CO2 to produce of to produce High-energy sugars ATP NADPH O2 Chloroplasts

Photosynthesis Light- dependent reactions Calvin cycle Thylakoid includes of take place in takes place in uses to produce use Light- dependent reactions Calvin cycle Thylakoid membranes Stroma NADPH ATP Energy from sunlight O2 Chloroplasts High-energy sugars

Photosynthesis is important for almost all life on Earth because it — A produces oxygen B uses simple elements C is responsible for most decay D releases usable forms of nitrogen

A B What is this picture showing? chloroplast What is letter A? __________ What is letter B? __________ chloroplast stroma thylakoid

Thylakoids CO2 H2O Light NADP+ ADP + P Calvin Cycle ATP NADPH Sugars Chloroplast Chloroplast NADP+ ADP + P Chloroplast Thylakoids Light- Dependent Reactions Calvin Cycle ATP NADPH O2

What gas is represented by letter A? _______ The diagram represents plant photosynthetic activities taking place in a “food factory.” CO2 What gas is represented by letter A? _______ What is represented by letter B? __________ C6H12O6

Light Dependent or Calvin Cycle? Occurs in the stroma Needs CO2 Produces ATP and NADPH Occurs in the thylakoid membranes Needs sunlight Can occur in the dark Uses ATP and NADPH Produces a 6-Carbon Sugar Calvin Cycle Calvin Cycle Light Dependent Light Dependent Light Dependent Calvin Cycle Calvin Cycle Calvin Cycle