Photosynthesis Converts sunlight energy into chemical energy

Chemical Equation 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Carbon dioxide and water are the reactants and glucose and oxygen are the products. Chlorophyll is the pigment necessary to run the reaction

Requirements Light Energy (Sun) Chlorophyll a,b and accessory pigments (these absorb wavelengths of light) Raw materials (CO 2 and H 2 O ) Enzyme: NADP (taxi cab)

Cross Section of a Leaf Leaf has many layers of specialized cells. Notice the location of the chloroplasts.

Stomate Stomate (leaf mouth) allows gas exchange (O 2 and CO 2 ) 2 guard cells create the stomate

Inside the Chloroplast Saclike membranes called thylakoids contain chlorophyll and accessory pigments. Stacks of thylakoids are called grana Stroma is the fluid filled space

Chloroplast Below Grana are stacks of thylakoids

Review 1)What is the photosynthetic equation? 2)What is the name of the “leaf mouth”? 3)What is the name of the fluid filled space in the chloroplast? 4)Where in the chloroplast is the chlorophyll located?

Stages of Photosynthesis Light Reactions (occurs in thylakoid) Calvin Cycle or Dark Reactions (occurs in stroma)

Light Reactions Overview: 1. Light energy is absorbed in the THYLAKOID 2. Water is split apart 3. CO 2 is NOT involved 4. ATP formed 5. Reactants: chlorophyll a & b, accessory pigments, light energy, water, and NADP

Light Reactions Steps: 1.Light energy is absorbed by chlorophyll. 2.Electrons in chlorophyll become “excited” (high energy) and split H 2 O apart. H 2 O: 2H + O 2- * 6 molecules of water total are split apart: 12 H +, 6 O 2- (released into air)

Light Reactions 3. NADP picks up H + and transports them across the thylakoid membrane into the stroma. NADP + H +  NADPH 6 H 2 O are split: 12 NADPH are formed

4.12 NADPH moves across the thylakoid membrane into the stroma and creates 12 ATPs.

Products of Light Reactions 6 O 2 are released into the air via stomate 12 NADPH and 12 ATP: go to the stroma for (Calvin Cycle)

Calvin Cycle or Dark Reactions Reactants: 12 ATP and 12 NADPH from Light Reactions 6 CO 2 6 RUBP (5 carbon sugar) Products: Glucose (C 6 H 12 O 6 ) and 6 RUBP Takes place in the stroma

Steps of the Calvin Cycle (Dark Reaction) CO 2 Fixation: CO 2 combines with RUBP CO 2 + RUBP  2 PGA PGA is a 3-Carbon molecule and is UNSTABLE! Total: 6 CO RUBP  12 PGA

Calvin Cycle 12 PGA + 12 ATP + 12 NADPH  12 PGAL + 12 ADP + 12 NADP * NADP and ADP go back to the light reactions

Calvin Cycle Formation of glucose: PGAL + PGAL  Glucose C 3 H 6 O 3 + C 3 H 6 O 3  C 6 H 12 O 6 * This only uses 2 of the 12 PGALs

Calvin Cycle The remaining 10 PGALs (30 carbon total) will reform into 6 RUBPs (each RUBP has 5 carbons) Those 6 RUBPs go back to the beginning of the Calvin Cycle

Calvin Cycle

Importance of Photosynthesis Forms glucose which is necessary for cellular respiration Forms the source of oxygen we breathe

Factors that Affect Photosynthesis 1. Amount of water 2. Temperature 3. Light Intensity 4. Amount of CO 2

Summary of Photosynthesis