Photosynthesis Light Absorption Sun gives off visible light

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

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

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

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: O 2, ATP, NADPH • 2) Light Independent Reactions – Creates: Glucose

Light Dependent Reactions

Light Dependent Reactions PSII thylakoid Thylakoid Stroma thylakoid Granum

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

Light Dependent Reactions e. H e H O e e e 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 e. H O PSII Stroma e. H O PSI

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

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

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

Light Dependent Summary • O 2, ATP, NADPH created • NO GLUCOSE CREATED!

Light Independent Reactions (Calvin Cycle) 5 C = Ru. BP C CC CC CC Stroma Step 1: • CO 2 from the air bonds with a 5 carbon molecule… 6 carbon molecule created

Light Independent Reactions (Calvin Cycle) 3 C = PGAL ATP C C C NADP H Stroma 3 C = 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) PGAL ATP PGAL C C C C C NADP H PGAL Stroma C C 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) Glucose C C C 6 H 12 O 6 Stroma C C C C C 5 CC= Ru. BP C C C C 5 C = Ru. BP C C C ATP C C C 5 C = Ru. BP 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 • CO 2, 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.

Review • Place these steps in order from start to finish: A) Electron transport chain creates NADPH and ATP energy B) 3 C molecule broken by ATP into 5 C molecule C) PGAL created when 6 C molecule broken down D) Water broken into H+, e-, and O components E) Sunlight causes chlorophyll electrons to flow into thylakoid membrane F) 3 C molecule bonds to create glucose G) CO 2 bonds with Ru. BP

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) CO 2 bonds with Ru. BP C) PGAL created when 6 C molecule broken down F) 3 C molecule bonds to create glucose B) 3 C molecule broken by ATP into 5 C molecule