Photosynthesis

Light Absorption Sun gives off visible light (ROYGBIV) Unabsorbed light reflects to our eyes Most green light not absorbed by leaves Chlorophyll absorbs sunlight Absorb mostly reds and blues

Prism White light

Which color(s) are being reflected Which color(s) are being reflected? Yellow Which color(s) are being absorbed? Red, Orange, Green, Blue, Indigo, Violet

Which color(s) are being reflected Which color(s) are being reflected? Blue Which color(s) are being absorbed? Red, Orange, Yellow, Green, Indigo, Violet

Which color(s) are being reflected Which color(s) are being reflected? None…Black is the absence of light Which color(s) are being absorbed? All….ROYGBIV

Which color(s) are being reflected Which color(s) are being reflected? All…ROYGBIV Which color(s) are being absorbed? None

Which color(s) are being reflected Which color(s) are being reflected? Green Which color(s) are being absorbed? Red, Orange, Yellow, Blue, Indigo, Violet

The Chloroplast Site of photosynthesis Thylakoid membranes: light dependent reactions Stroma (fluid interior): light independent reactions

Stomata: pore underneath leaves through which gases enter/exit

Photosynthesis Overview Two Stages 1) Light Dependent Reactions Photosystems: groups of molecules that capture/transfer energy Creates: O2, ATP, NADPH 2) Light Independent Reactions Creates: Glucose

Light Dependent Reactions: Photosystem II Step 1: Chlorophyll absorbs sunlight Chlorophyll e- become excited & transfer to thylakoid membrane Thylakoid membrane becomes negatively charged Starts an electron transport chain

H2O broken into H+, e-, and O Step 2 & 3: H2O broken into H+, e-, and O e- replace those lost by chlorophyll O waste H+ pumped inside the thylakoids and accumulate

Thylakoid membrane Thylakoid membrane becomes negatively charged e e e e e e e e e chlorophyll chlorophyll e e H e Electrons replace those which left chlorophyll H e e H O e H H H Oxygen waste is released O O

The process keeps repeating The plants takes in water H H H H e e e e e e Thylakoid membrane Thylakoid membrane becomes negatively charged e e e e e e e e e e e e e e e e e e chlorophyll chlorophyll e e H e Electrons replace those which left chlorophyll H e e H O e H H H Oxygen waste is released O O

Light Dependent Reactions: Photosystem I Chlorophyll absorbs sunlight Chlorophyll e- become excited & transfer to thylakoid membrane Accumulate with those from photosystem II e- e- e- e- e-

NADPH produced (H taxi) e- causes H+ to bond with NADP NADPH will be used later ATP produced H+ ions diffuse and bond ADP with Pi ATP will be used later H+ H+ H+ e- e- e- e- e- e- e- e- e- e- e- ATP ATP ATP

Light Dependent Summary O2, ATP, NADPH created NO GLUCOSE CREATED!

Light Independent Reactions (Calvin Cycle) Step 1: CO2 bonds with RuBP (5C) molecule to make a 6C molecule

RuBP 6C molecule CO2 bonds with RuBP C C Six carbon molecule is created CO2

Step 2: 6C molecule splits into two PGAL molecules (3C) ATP & NADPH provide the energy

NADPH NADPH NADPH NADPH NADPH NADPH NADPH (from light dependent cycle) drops off H ATP (from light dependent cycle) provides energy to break the molecule into PGAL ATP 6C molecule ADP H H H ADP ADP ADP ATP ADP ADP ATP C C C C C C C C ATP ATP H H H ATP PGAL PGAL

Step 3: Some PGAL (3C) bonds to make glucose (6C) Some PGAL recycled to start the cycle over

PGAL PGAL PGAL PGAL glucose! C C PGAL PGAL C C C C C C C C C C PGAL glucose! PGAL bonds with PGAL….to make glucose! Glucose is used by plant cell mitochondria to create ATP in the process of cellular respiration PGAL is used to restart the Calvin Cycle

Step 4: PGAL (3C) bonds to remake a RuBP (5C) molecule with help of ATP CO2 bonds with RuBP (5C) to restart the cycle

C C C C C C C C C C C C C C C ATP ATP ATP PGAL broken apart by ATP

6C molecule 6C molecule 6C molecule RuBP C C C C C C C C C C C C C C C CO2 C C C C 6C molecule C C C C C C C C CO2 RuBP C CO2 Unstable C atoms recombine to make RuBP (5C) molecules RuBP molecules bond with CO2 again

Light Independent Summary CO2, ATP, & NADPH create glucose

Your essay question on the next test! Trace the flow of energy, including ATP, from the sun to your muscles, after eating a green leaf salad.

Kobe Kuiz Place these steps in order from start to finish: A) Electron transport chain creates NADPH and ATP energy B) 3C molecule broken by ATP into 5C molecule C) PGAL created when 6C molecule broken down D) Water broken into H+, e-, and O components E) Sunlight causes chlorophyll electrons to flow into thylakoid membrane F) 3C molecule bonds to create glucose G) CO2 bonds with RuBP

Kobe Kuiz Place these steps in order from start to finish: E) Sunlight causes chlorophyll electrons to flow into thylakoid membrane D) Water broken into H+, e-, and O components A) Electron transport chain creates NADPH and ATP energy G) CO2 bonds with RuBP C) PGAL created when 6C molecule broken down F) 3C molecule bonds to create glucose B) 3C molecule broken by ATP into 5C molecule