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

Light Dependent Reactions Stroma PSI PSII Thylakoid thylakoid thylakoid Granum thylakoid

Light Dependent Reactions Stroma Light Dependent Reactions H H H H H H O O O PSI PSII Thylakoid e e e e e e Step 1: Chlorophyll in PSII absorbs sunlight and electrons become excited Thylakoid membrane becomes negatively charged Starts an “electron transport chain”

Light Dependent Reactions Stroma Light Dependent Reactions e e H H H H e e e H e H O O O PSI e e e e e e PSII Thylakoid Step 2 & 3: Water molecules are broken H+ pulled into thylakoids Electrons replace those lost by chlorophyll to keep cycle going Oxygen waste released

Light Dependent Reactions Stroma Light Dependent Reactions PSI e e e e e e e e e PSII e Thylakoid e e H H H H H H Step 4: Chlorophyll in PSI absorbs sunlight and electrons become excited

Light Dependent Reactions Stroma Light Dependent Reactions PSI e e e e e e PSII e Thylakoid H e e e H H NADP H H e H H e H NADP Step 5: Electrons help bond NADP + H to create NADPH (H taxi) NADPH will be used later

Light Dependent Reactions Stroma Light Dependent Reactions PSI e e e e e e PSII e Thylakoid e e e H H H H H e H ATP synthase ATP ATP ATP Step 6 & 7: H+ diffuses into the stroma H+ helps bond ADP + P to create ATP ATP will be used later P ADP P ADP ADP P

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

Light Independent Reactions (Calvin Cycle) Stroma Light Independent Reactions (Calvin Cycle) 5C = RuBP C C CO2 Step 1: CO2 from the air bonds with a 5 carbon molecule… 6 carbon molecule created

Light Independent Reactions (Calvin Cycle) Stroma 3C = PGAL ATP C C C NADP H 3C = PGAL Step 2: ATP and NADPH (from light dependent cycle) finally used! 6 carbon molecule broken into two 3 carbon molecules

Light Independent Reactions (Calvin Cycle) Stroma Light Independent Reactions (Calvin Cycle) PGAL PGAL ATP C C C C NADP H PGAL PGAL C ATP PGAL C C C NADP H PGAL Step 2: ATP and NADPH (from light dependent cycle) finally used! 6 carbon molecule broken into two 3 carbon molecules Process repeats

Light Independent Reactions (Calvin Cycle) Stroma Light Independent Reactions (Calvin Cycle) Glucose C6H12O6 C C C C C C C C C 5C = RuBP C C C C C ATP 5C = RuBP C C C C 5C = RuBP C C C Step 3 and 4: Some 3 carbon molecules will bond to make GLUCOSE! Other 3 carbon molecules will recombine to make 5 carbon molecule

Light Independent Summary CO2, ATP, & NADPH create glucose

Light Independent Reactions (Calvin Cycle)

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.

Recap 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