Photosynthesis• Endothermic reaction: Reaction

that absorbs energy (sunlight)• Who: Producers/Autotrophs

(Plants, algae, bacteria)

• Where: Chloroplasts1) Granum (pl. Grana)

– Stacks of disked shaped structures called thylakoids that house chlorophyll

2) Stroma – Fluid that surrounds the grana.– Similar to the cell’s cytoplasm

• Defined: Process that captures solar energy to make sugars

• End Result: Sugar & oxygen as waste

Light Absorption

• Sun gives off visible light– Red, Orange, Yellow, Green, Blue, Indigo, Violet

• We see reflected light– Red objects = reflect red light– Blue objects = reflect blue light

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? GreenWhich color(s) are being absorbed?

Red, Orange, Yellow, Blue, Indigo, Violet

Light Absorption

• With leaves, green light reflected– That’s why leaves look green– Green light not used by plants

• Reds and blues most used in photosynthesis

Green reflected

Red, Orange, Yellow, Blue, Violet absorbed into the leaf

• Where: Thylakoid membranes of chloroplast• What happens?

1) Sunlight converted into ATP energy2) Water (H2O) broken apart

• Hydrogen kept for later use; Oxygen is released as a waste• End result: ATP (transferred to the light-independent rxns), H2, Oxygen

Stage 1: Light Dependent (Light Reactions)

H2 OATP

ATPATPH2 OH2 O

H2OATPATP

ATP

H2 OH2O

Thylakoid Membrane

Thylakoid Membrane

Thylakoid Membrane

Stage 1: Light Dependent (Light Reactions)

What is used during the light dependent stage?

What is created during the light dependent stage?

• Where: Stroma (fluid interior) of chloroplast• What happens?

– CO2 taken in– ATP breaks apart CO2 + H2

– C’s, O’s, and H’s recombine into C6H12O6 (Glucose)

Stage 2: Light Independent (Dark Reactions)

ATP

ATP

ATP

H2

H2

H2

H2

H2

H2

CO2

CO2

CO2

CO2

CO2

CO2

ATP

ATP

ATP

H HH

HH

HHHHH

H

H

C

C

C

C

CC

OO

OO

OO

OO

OOOO

C6H12O6

C6H12O6C6H12O6

C6H12O6

Stage 2: Light Independent (Dark Reactions)

What is used during the light independent stage?

What is created during the light independent stage?

The equation for the overall process of photosynthesis:

6CO2 + 6H2O C6H12O6 + 6O2

C6H12O6

Granum (stack of thylakoids)

Thylakoid

Sunlight

= 1 six-carbon sugar

6H2O

6CO2

6O2

ChloroplastChloroplast

1

2

43

energyStroma (fluid outside the thylakoids)

Connection between photosynthesis & respiration

• In Plants– Create glucose through photosynthesis– Glucose is used to make ATP through cellular respiration

Plant Cell

glucose

glucosechloroplast

chloroplast ATP

ATP

mitochondria

mitochondria

Connection between photosynthesis & respiration

• In Animals– Plants create glucose through photosynthesis– Animals eat the plants – Glucose is used to make ATP through cellular respiration

Plant Cell

glucoseglucoseglucosechloroplast

GlucoseGlucoseGlucose

Animal Cell

mitochondriaATP

Glucose(from food)

REview1. Which color(s) is/are absorbed by a typical red apple?2. Which color(s) is/are reflected by a typical red apple?3. What is a producer/autotroph?4. What is used during the light dependent reactions?5. What created during the light dependent reactions?6. What is used during the light independent reactions?7. What created during the light independent reactions?8. True or False: Plants are the only photosynthetic

organisms.