Photosynthesis: An Overview Chapter 8

ATP Energy Storage

How do heterotrophic organisms get energy?  Consume “food.”  Macromolecules that provide energy:  Lipids  Proteins  Carbohydrates How do they use energy?

ATP: Adenosine Triphosphate molecule energy-carrying molecule storage releasing Used for short term storage & releasing of energy Adenine Ribose 3 Phosphate Groups high energy bonds

ADP and ATP are constantly being recycled recycled by the living cell Use energy to ADD phosphate group Break bond to LOSE phosphate group to release energy IN OUT

NADP+ and NADPH are similar with adding a Hydrogen ATP ADPpartially ADP is like a partially-charged battery, ATPfully while ATP is said to be fully-charged. ADPATP Energy Adenosine triphosphate (ATP) Partially charged battery Fully charged battery

Why do cells need energy? To carry out active transport  Such as ion pumps To move organelles within the cell To synthesize (make) proteins & sugars for life functions ONE sugar molecule stores x90 more energy than ATP

Photosynthesis Gathering Light Energy from the Sun

PSN uses Visible Light from the SUN Travels in wavelengths Distance between crests determines color & energy Color seen is reflected, all others are absorbed

Absorption of Light by Chlorophyll a and Chlorophyll b Section 8-2 Figure 8-5 Chlorophyll Light Absorption Pigments = molecules that reflect/absorb light Chlorophyll  in chloroplasts  photo-sensitive membrane captures solar energy Xanthophylls Carotenoids

Chloroplasts In a plant Micrograph of a chloroplast

Chloroplasts Structure

Light Energy Chloroplast CO 2 + H 2 OSugars + O 2 Section 8-2 Photosynthesis: Reactants and Products PhotosynthesisPhotosynthesis time for a SCIENCE video

Photosynthesis PART 1. Light-Dependent Reactions  In the thylakoid  Chlorophyll absorbs sun’s energy  Energy transferred to electrons  Like “Hot potatoes”  H 2 0 SPLIT & O 2 is by products  Charge up & Carry Energy  NADP+  NADPH  ADP  ATP  Think of these like an oven mitt to carry “hot potatoes”

Photosynthesis Part 2. Light-Independent = Calvin Cycle  (sunlight not directly needed)  In the stroma  CO 2 comes in and NADPH and ATP convert it to glucose (C 6 H 12 O 6 )

The Photosynthesis Equation light 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Carbon Water Glucose Oxygen Dioxide (Sugar)

8.3 The Reactions of Photosynthesis

Light-dependent Reactions  Photosystem: light capturing unit containing chlorophyll  Electron transport system: electron carrier molecules that shuttle electrons, energy released to make ATP  Electrons in chlorophyll must be replaced by electrons from water so that cycle may continue; oxygen is liberated from the light reactions  Light reactions make ATP and NADPH used to fuel the reactions of the Calvin cycle (light independent reactions)

Light Independent Reaction /Calvin Cycle  ATP and NADPH from light reactions used to break CO 2 apart, then reassemble the carbons into glucose.  Called carbon fixation: taking carbon from an inorganic molecule (atmospheric CO 2 ) and making an organic molecule out of it (glucose)

In your comp book:  Label the parts of a chloroplast on diagram provided p. 231  Organize information: Light-dependent reactions Light-independent reactions Definition Where take place Reactants Products