What color does chlorophyll reflect? 2. What organisms can make their own energy (there are at least 4 correct answers)? Question of the Day

1-10 Photosynthesis uses… Photosynthesis produces… Review Organisms that make their own energy = ??? Organisms that have to eat to get their energy = ??? 3 cellular activities that require energy = …

1-10 Photosynthetic pigments … What colors does a plant primarily use for photosynthesis? How do you know? Review

How are heterotrophs and autotrophs different? Question of the Day

Why is the sky blue? ure/climate- weather/atmospheric/sky.htm srsky/misr_sky.shtml

Photosynthesis  Light is absorbed – excites electrons in pigments = start of photosynthesis  Explain why a leaf appears green  Because it is absorbing most of the other wavelengths of light and reflecting green

Lets Photosynthesize!  It all starts with a….

Lets Photosynthesize! Calvin cycle 1 st stage 2 nd stage

Lets Photosynthesize!

LETS PHOTOSYNTHESIZE! Light reactions = first stage of photosynthesis – light energy is converted to chemical energy (energy from the sun  ATP + NADPH)

The Leaf  What organelle in the leaf is responsible for photosynthesis?  Chloroplast  Parts of a chloroplast  Thylakoids - Flattened sacs where photosynthesis occurs – surrounded by a membrane  Grana –  Stacks of thylakoids  Stroma –  Solution that surrounds the grana

The Light-Dependent Reactions: Generating ATP and NADPH  The light-dependent reactions encompass the steps of photosynthesis that directly involve sunlight.  The light-dependent reactions occur in the thylakoids of chloroplasts.

 Thylakoids contain clusters of chlorophyll and proteins known as photosystems.  Photosystems absorb sunlight and generate high-energy electrons that are then passed to a series of electron carriers embedded in the thylakoid membrane. The Light-Dependent Reactions: Generating ATP and NADPH

Chloroplast

Light Reactions 1.Occurs on thylakoid membrane 2.Chlorophyll absorbs light and electrons get excited – flow on electron transport chain 3.Energy in excited electrons is used to create NADPH and ATP  These are temporary energy carrier molecules 4.Water – electron donor – releases O 2 5.ATP + NADPH are then used to create glucose in the Calvin Cycle

 Chlorophyll absorbs light and electrons are excited. These electrons flow on electron transport chain along the thylakoid membrane. As the electron is transported it loses some energy and is used create a H+ concentration gradient inside the thylakoid, which is later used to create ATP from ADP +P. The electron finally reaches the final electron acceptor and is combined with NADP+ and a H+ to form NADPH, which is an energy carrier molecule. Water is split to (2 H 2 O = 4H + + 4e - + O 2 ) to replace the lost electrons.

One of the most important steps (water molecules split): 2 H 2 O = 4H + + 4e - + O 2 Light Reactions protons electrons oxygen

1. During the light reactions ___ and ___ are used to make ___, ___, and ___. REVIEW

DRAW! Also label: thylakoid grana stroma

During the light reactions ___ and ___ are used to make ___, ___, and ___. Question of the Day

One of the most important steps (water molecules split): 2 H 2 O = 4H + + 4e - + O 2 Light Reactions protons electrons oxygen

Light Reactions

1-13 Quiz up to and including the light reactions (notes pages 1-7) on Wednesday 1-19 Announcement

How are heterotrophs and autotrophs different? REVIEW 2. Photosynthetic pigments … 3. What colors does a plant primarily use for photosynthesis? How do you know?

Photosynthesis uses… Photosynthesis produces… Review 5. Where do the light reactions take place? 6. Why is the splitting of water molecules important for photosynthesis?

1-13 Review 7. The light rxns use… To produce… 8. What’s the electron transport chain?

1-14 During the light reactions water is split apart into ____, ____, and ____ Question of the Day

Light Reactions

What happens during step # 1 above? Chlorophyll absorbs light energy and its electrons become excited and move to the electron transport chain What happens during steps # 2-3 above? The excited electrons move through the proteins of the electron transport chain What happens during step # 4 above? Light excites electrons on Photosystem I (accessory pigments) Light Reactions

What happens between steps 4 and 5 above? The excited electrons move through the proteins of the electron transport chain What happens during step # 5 above? NADP + and H + are combined to form NADPH Light Reactions

Summary

Explain what’s going on with protons above: 1. _____ splits apart producing PROTONS, electrons, and oxygen. 2. Protons can only leave the thylakoid through an _____________________________. The movement of protons through this carrier protein provides the energy needed to form _____ from __________. 3. Some of the protons are pumped back into the thylakoid and some are used to make ________ from NADP+ and H+. H2OH2O ATP producing carrier protein ATPADP + P NADPH