Photosynthesis Overview video Photosynthesis 3 mins Overview video Photosynthesis 3 mins

Photosynthesis animation

1) Photosynthesis  When plants (photoautotrophs) make their own food from sunlight, building sugars from CO2.

2) Photosynthesis equation  Carbon Dioxide + Water + SUN  Sugar + Oxygen  CO 2 + H 2 O + SUN  C 6 H 12 O 6 + O 2

3) Photosynthesis occurs in the chloroplasts

4) Thylakoids – disks inside chloroplast where photosynthesis occurs  Grana – Stacks of thylakoids  Stroma – The fluid surrounding thylakoid

5) Pigments –  Substances that absorb visible light  Found in the membrane of thylakoid

6) Chlorophyll The green pigment in plant chloroplasts that absorbs the most light for photosynthesis

What color is the truck? Demo

What color is the truck now?

What color is truck now?

7) Chlorophyll absorbs mostly blue and red light Green light is reflected

8) Why Do plants appear Green? Red and blue absorb into chlorophyll Green is reflected Green

9) Why do Leaves change color in the fall?  Green leaves have pigments of different colors beside chlorophyll.  Usually the other colors are hidden by the great amount of chlorophyll.  When the leaf dies and loses its chlorophyll, the other pigments (orange, red, yellow) become visible.

10) 2 basic steps for photosynthesis A) Light reactions (light dependent) B) Dark reactions (light independent)

C) Light reactions convert light to chemical energy D) Dark reactions turn chemical energy into Sugars

11) Light reactions Called light dependent because they MUST have light to occur Have two parts called photosystems And occur in the Thylakoid membrane

12) Photosystem II (PSII) Comes first!! PSII Purpose  Break water to generate electrons A) Sunlight hits Chlorophyll A which is called the reaction center

Photosystem II (PSII) B) This releases electrons which travel through molecules in the electron transport chain (ETC) ending at PSI PS II PS I

Photosystem II C) water splits into protons, electrons and oxygen. This provides more electrons to travel to down ETC to PSI H 2 0  H + + e - + O 2

13) Oxygen comes from the H 2 O 2H 2 0  4 H e - + O 2 Oxygen (O 2 ) – Released as a gas, Oxygen is NOT needed for photosynthesis

14) Photosystem I (PSI) comes 2 nd PSI Purpose  form energy molecules ATP and NADPH A) Electrons from ETC reach PSI reaction center in a second molecule of Chlorophyll A

Photosystem I B) Sun helps electrons go through a 2 nd ETC (Electron transport chain) in Causing NADP+ to turn into NADPH

Photosystem I C) ATP synthase enzyme pushes protons (H + ) out of membrane to make ATP H+

Overview light reactions

Animation – light dependant reaction  ary/source/61a.swf ary/source/61a.swf ary/source/61a.swf

15) Summary of light reactions  H sunlight + NADP + + ADP  O 2 + NADPH + ATP  The energy molecules NADPH and ATP can not be stored for long.  They will be used in Dark reactions to make sugar

16) Dark reactions = Calvin Cycle = Light INdependent reactions  The process of using ATP and NADPH energy to join CO 2 into sugars

17) WHY is the Calvin Cycle called the Light independent reactions?  They can happen in light OR dark  The Calvin Uses ATP and NADPH from the light reactions to make Sugar  If is no light, The Calvin Cycle soothere n uses up its ATP and NADPH and stops working.

18) Calvin Cycle builds sugar from CO 2 1 turns of the cycle adds 1 carbon to sugar 3 turns of the cycle produce a 3 carbon sugar. 6 turns of the cycle forms a 6 carbon glucose

19) What happens to the 3 carbon sugars?  They can form: GlucoseSucroseStarches amino acids (using Nitrogen) And other organic molecules

20) Summary of Dark Reactions  CO 2 + NADPH + ATP  Sugar + NADP + + ADP + P

21) Photosynthesis Overview 1 st – The light dependent reactions change light energy to chemical energy in form of ATP and NADPH 2 nd – The light independent reactions use the ATP and NADPH to build sugar from carbon dioxide