Today’s Date Objective here

Brainteaser I am around long before dawn. But by lunch I am usually gone. You can see me summer, fall, and spring. I like to get on everything. But when winter winds start to blow; Burr, then it's time for me to go! What am I?

Lets Review What is photosynthesis? Where does photosynthesis take place What is the formula for photosynthesis

Photosynthesis means building with Light ‘synthesis’ = BUILD ‘photo’ = LIGHT Photosynthesis means building with Light carbon dioxide CO2 water H2O + glucose C6H12O6 oxygen O2 + chlorophyll  Green plants can make their own food from …6CO2 and 6H20…..…  using energy in the form of ……light…………….  which is absorbed by chlorophyll in the …chloroplast…...  The end products of photosynthesis are …C6H12O6 and …6O2……….

Photosynthesis Light Reactions

Today you will learn There are 2 parts to photosynthesis. Where the light reactions take place. What do the light reactions produce? There are 3 parts to the Calvin cycle. Where the dark reactions take place. What the dark reactions produce?

Photosynthesis is divided into two sets of reactions Light Reactions Dark Reactions Light Independent Reactions Light Dependent Reactions Calvin Cycle

Where do the light reactions take place? take place within the thylakoid membranes of the chloroplasts Thylakoid

What is the purpose of the light reactions? Convert the light energy into chemical energy The chemical energy is in the form of ATP (Adenine Triphosphate) and NADPH (nicotinamide adenine nucleotide phosphate) Split H2O and release O2 atmosphere

Why make ATP and NADPH? Energy is needed to start the chemical reaction Chemical reaction will make sugar.

How is ATP and NADPH made? The light-dependent reactions are comprised of two sets of reactions called photosystems. Photosystems I Photosystems II

Photosystem II A T P Begins with absorption of energy (photon) by a chlorophyll molecule (Chl). The chlorophyll molecule is raised to an excited state. The electron lost by the chlorophyll is replaced by the enzymatic splitting of water

This electron is passed down a chain of molecules called the electron transport chain or redox chain. A T P Energy from this transfer of electrons is used to produce ATP, leaving the electron in a low energy state to be recharged by Photosystem I Photosystem II

N A D P H Photosystem I The low energy electron from photosystem II replaces one that in photosystem I that has become energized and left the chlorophyll Molecule in photosystem II. Energy from this excited electron is exchanged across different molecules (called carriers) ultimately being used to convert NADP+ to NADPH. NADPH stores this electrical energy for use in the light independent reactions. Photosystem I

Photosystem II and Photosystem I ATP NADPH

Summary Light Reactions Make What? Occur Where? ATP NADPH Thylakoids PS II PS I

Dark Reactions Calvin Cycle

Where do the dark reactions take place? In the stroma of the chloroplast. The stroma is the juice in the chloroplast. Stroma

What is the purpose of the dark reactions? To use chemical energy to fix CO2 into glucose. The chemical energy is ATP and NADPH that was produced in the light reactions

How do we make Glucose? ATP and NADPH are used to incorporate CO2 into carbohydrate via a cyclic pathway called the Calvin-Benson cycle. The Calvin Cycle is made up of three phases. CO2 Fixation Reduction Regeneration of RuBP

Calvin Cycle: Step 1- CO2 Fixation CO2 diffuses into the stroma from the surrounding cytosol. An enzyme combines the CO2 molecule with a five-carbon sugar called RuBP. The product is a six- carbon molecule that immediately splits into 2 three molecules known as PGA.

Calvin Cycle: Step 2 - Reduction PGA is converted into another three carbon molecule called PGAL in a two-step process. First, a molecule of ATP (made during the light cycle) gives PGA a phosphate group. Next, a NADPH (also made during the light cycle) gives PGA a proton (H+). PGA releases a phosphate group and is now PGAL.

Calvin Cycle: Step 3- Regeneration In step 3, some of the PGAL is “recycled” and turned back into RuBP so that the cycle can continue. Some of the PGAL is taken away and turned into organic compounds like sugars, lipids, and amino acids.

So what just happened? Every turn of the Calvin cycle adds one more carbon into the cycle. So, every three turns makes a new 3- carbon PGAL molecule. This means that 6 turns through the cycle would give you enough carbon to make a glucose molecule! For every PGAL molecule made, it takes 9 molecules of ATP and 6 NADPH. The PGAL molecules can be used to make whatever organic compounds the plant needs to produce.

Review of Photosynthesis includes Light dependent reactions Light independent reactions occurs in uses uses occur in Light Energy Thylakoid membranes Stroma ATP NADPH to produce of to produce ATP NADPH O2 Chloroplasts Glucose

The primary function of the light reactions of photosynthesis is To produce energy-rich glucose from carbon dioxide and water To produce ATP and NADPH To convert light energy to the chemical energy of PGAL To use ATP to make glucose

How well did you do today? During photosynthesis, A) there is no ATP production B) ATP production occurs during the light-dependent reactions C) ATP production occurs during the dark reactions D) ATP production is replaced by NADPH production.

How well did you do today? Where does the Calvin cycle of photosynthesis take place? Stroma of the chloroplast Thylakoid membrane Cytoplasm surrounding the chloroplast Outer membrane of the chloroplast