Photosynthesis!

Photosynthesis• Photosynthesis – Chemical process– Plants absorb sunlight• Convert light energy into stored chemical energy

• Why do plants need this energy?

Where it happens• Photosynthesis occurs in green pigments– Called chlorophyll– Found in chloroplasts• Usually found in mesophyll tissue of leaves

• Each mesophyll cell contains between 20-100 chloroplasts

Xylem &Phloem

Chloroplasts• Chloroplasts have membrane to contain the

fluid inside

• Fluid-filled area is called Stroma– It contains enzymes needed for photosynthetic

reactions

• Also inside chloroplasts:– Thylakoids• Set of interconnected flat, disk-like sacs• A stack of them that look like a stack of coins are called

Grana

Chloroplasts

Chlorophyll• Chlorophyll is a complex molecule– Main pigment of photosynthesis

• Three pigments are needed for photosynthesis

Chlorophyll• Chlorophyll a– Bright green– Absorbs energy from a specific range of light• Violet-blue to red and red-orange wavelengths

– Initiates light dependant reactions

Chlorophyll• Chlorophyll b– Yellow green in color– Absorbs light wavelengths slightly different than

Chlorophyll a• Carotenoids– Yellow and orange in color– Absorb energy from green-yellow-orange

wavelengths– Energy absorbed can be transferred to Chlorophyll a

Process of Photosynthesis

1. Trap light energy2. Convert light energy into chemical energy

• That is it• Then the plant can use the chemical

energy(sugar) to grow

• What traps the light energy?– chlorophyll

• That energy is used to manufacture high-energy compounds– What is a compound?– ATP, NADPH• Adenosine triphosphate• Nicotinamide adenine dinucleotide phosphate

Process of Photosynthesis

• The ATP and NADPH are then used to make carbohydrates– Sugar, Starch, Cellulose

• Sugar and starch are the cells’ energy source• Cellulose is what makes up cell walls in plant

cells• Watch it

Process of Photosynthesis

• Two main reactions in the process of photosynthesis

Process of Photosynthesis