Photosynthesis

Introduction Light reaction Photosynthesis Introduction Light reaction

Cell Energy: Energy for living things comes from food. Originally, the energy in food comes from the sun.

Organisms that CANNOT use the sun’s energy to make food—heterotrophs Ex: animals and most microorganisms

Organisms that use light energy from the sun to produce food—autotrophs (auto = self) Ex: plants and some microorganisms (some bacteria and protists)

Photosynthetic Organisms are Producers

Photosynthesis is the process by which the energy of sunlight is converted into the energy of glucose

Photosynthesis occurs on plant leaves

Leaf Anatomy Protects the leaf Lets CO2 in and O2 out

More specifically, photosynthesis occurs in the chloroplasts of leaf granum

Chloroplast Structure: Structure:

_____________ (absorbs light) http://www.russianflora.com/store/images/product/custom_green_plant_35.jpg The main energy absorbing molecule in chloroplasts is _____________ (absorbs light) ______________ are plant pigments too. (These look yellow, orange, and red). As chlorophyll dies in the fall, the green color fades and is replaced by carotenoids CHLOROPHYLL CAROTENOIDS http://www.rnzih.org.nz/images/gardenimages/carrots_d.jpg

Carotenoids are plant pigments too. http://www.russianflora.com/store/images/product/custom_green_plant_35.jpg Carotenoids are plant pigments too. These look yellow, orange, and red. As chlorophyll dies in the fall, the green color fades and is replaced by carotenoids http://www.rnzih.org.nz/images/gardenimages/carrots_d.jpg

Chlorophyll absorbs mostly red and blue wavelengths of light Red and blue absorbed Green is reflected

Photosynthesis Overview

Two Main Stages of Photosynthesis Light-Independent Reactions (Calvin Cycle) Light- Dependent Reactions

Part 1: Light-Dependent Reaction Occurs in thylakoids/grana Sun’s energy is absorbed and water is taken in & changed into chemical energy (ATP & NADPH)

Bigger Picture Take in light and water Produced is Oxygen as waste, NADPH, and ATP

5 steps of light rxn Light strikes thylakoid & hits chlorophyll causing electrons become excited.

5 steps of light rxn 2. Electrons jump from chlorophyll to chlorophyll through thylakoid membrane (electron transport chain). NADP+ picks up high energy e- & H+ to become NADPH.

H2O is split by light (photolysis)– electrons are given back to chlorophyll, H+ collects, & O2 is released (waste product you breathe)

4. H+ builds up inside thylakoid. 5 4. H+ builds up inside thylakoid. 5. H+ pass through transport protein (ATP synthase) which adds P to ADP forming ATP.

Talk to a Neighbor… Using the following diagram, walk your partner through the 5 steps of the light- dependent reactions

At the end of the Light-Dependent Reactions…

Summary of Light Rxn Video clip Using light energy ADP NADP+ H2O changed into ATP NADPH H+ & O2