6CO2 + 6H2O + sunlight  C6H12O6 + 6O2 PHOTOSYNTHESIS Autotrophic Process: Plants and plant-like organisms make their energy (glucose) from sunlight. Stored as starch if not immediately used for energy 6CO2 + 6H2O + sunlight  C6H12O6 + 6O2

Why is Photosynthesis important? Makes glucose out of inorganic materials -- carbon dioxide and water It begins all food chains/webs. Thus all life is supported by this process. It also makes oxygen gas as bi-product!!

Photosynthesis-starts ecological food webs!

Autotrophs make glucose and heterotrophs are consumers of it. Photo-synthesis (putting together using light) Autotrophs make glucose and heterotrophs are consumers of it.

Photosynthesis 6CO2 + 6H2O + energy  C6H12O6 + 6O2 Carbon dioxide + water glucose + oxygen sunlight absorbed by chlorophyll 6CO2 + 6H2O + energy  C6H12O6 + 6O2

Plant leaves have many types of cells!

Plant Cells

Leaf Structures • Cuticle –– waxy layer to prevent water loss • Stomata –- gas exchange • Cuticle –– waxy layer to prevent water loss  Spongy mesophyll –– gas storage • Palisade mesophyll –– site of photosynthesis • Vascular bundle –– transportation of food/H20 • Lower and upper epidermis - protection

Stomata Prevents H20 Loss • Cuticle –– waxy layer (lipid) • Stomata –– openings in the cuticle –– open at night/closed during the day –– allow for gas exchange (O2 & CO2) –– plants lose 90% of their water

Stomata in the desert NIGHT • Release H2O/O2 • Take in CO2 DAY Partly closed to prevent H20 loss

Chloroplasts • ATP, sugars, & other organic compounds • Structure: –– Disk-shaped, double outer membrane –– Folded inner membrane (thylakoid) arranged in stacks (grana) –– Semifluid interior (stroma)

Leaf absorbs light energy from sun to make chemical energy  glucose Leaf Pigments Leaf absorbs light energy from sun to make chemical energy  glucose Pigments in chloroplasts absorb different colors of white light (ROY G BIV) and reflect others Chlorophyll a and Chlorophyll b Carotene, xanthophyll, and anthrocyanins

Visible light is only a small part of the electromagnetic spectrum (all forms of light). Wavelength (nm)

Light behaves as if it were made of "units" or "packets" of energy that travel in waves. These packets are photons. The wavelength of light determines its color. The faster the wavelength, the greater the amount of energy in the wavelength

WHY ARE PLANTS GREEN? Different wavelengths of visible light are seen by the human eye as different colors. Gamma rays Micro- waves Radio waves X-rays UV Infrared Visible light Wavelength (nm)

The feathers of male cardinals are loaded with carotenoid pigments The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others. Reflected light Sunlight minus absorbed wavelengths or colors equals the apparent color of an object.

Why are plants green? Reflected light

Plant cells have green-reflecting chloroplasts WHY ARE PLANTS GREEN? Plant cells have green-reflecting chloroplasts The thylakoid membrane of the chloroplast contains photosynthetic pigments which each reflect certain colors.

The color of light seen is the color NOT absorbed. Chloroplasts absorb light energy and convert it to chemical energy Chloroplasts reflecting mostly green light because of the pigment chlorophyll Reflected light Light Absorbed light Transmitted light

Notice that plants do not absorb much green light Notice that plants do not absorb much green light. Plants are green so why do they not use green light for photosynthesis?

Two processes occur in photosynthesis:  Light reactions which require sunlight and only occur during daytime ̶ “Light-Dependent” Reactions ̶ Occurs in the thylakoid membranes (stacks of discs)  Dark reactions which occur all day and do not need light ̶ “Light-Independent” Reactions ̶ Occurs in Stroma (fluid portion of chloroplasts) ̶ Also called Calvin Cycle

ATP = Adenosine Triphosphate The source of energy that powers cellular work is ATP ATP consists of the nitrogenous base adenine, the sugar ribose, and a chain of three phosphate groups.

So, where is the energy? The bonds between phosphate groups can be broken by hydrolysis. Hydrolysis = process that breaks molecules down using water. When the last phosphate bond is broken, “free energy” is released into the cell

ATP is a rechargeable molecule ATP is a renewable resource that is continually regenerated by adding a phosphate group back to ADP. ADP + P = ATP ATP – P = ADP Energy from other reactions FUN FACT: In a working muscle cell, all ATP is recycled once each minute, over 10 million ATP consumed and regenerated per second per cell. WOW!

NADP+ = enyzme NADP+ is really “Nicotinamide Adenine Dinucleotide Phosphate” NADP+ is a carrier molecule that transports high energy electrons from the thylakoids to the stroma. H+ NADPH These enzymes can transport electrons without losing any of their energy. Thylakoids Stroma

Light-Dependent Reactions The first part of photosynthesis is called the light-dependent reactions. This reaction happens when the light energy is captured and pushed into a chemical called ATP.  Water is also broken down and its H+ and electrons are used (NADPH). O2 is not needed so it’s given off by the plant.

Light-Independent Reactions “Calvin Cycle” The second part of photosynthesis happens when the ATP is used to make glucose ATP supplies energy and NADPH supplies H+ and high energy electrons Two turns of the cycle produce one glucose. The Calvin Cycle uses carbon dioxide as the source of carbons needed to make glucose

As a Review: The Light Reactions occur in the thylakoid membranes and require sunlight. H20 is split and oxygen given off. Energy from electrons stored in ATP H+ carried to the dark reactions by NADP+ The Calvin Cycle uses CO2, ATP, H+ and electrons to make glucose. Also called the dark reactions since they don’t require light. Occurs in the stroma. C6H12O6 Glucose

Photosynthesis Animations “The Photosynthesis Story” Photosynthesis Review Click Picture Below Photosynthesis Song Click Picture Below