PhotosynthesisBy Amanda Elliott

Photosynthesis

• Occurs in the chloroplast • A double-membraned organelle

• Stroma – inner fluid• Thylakoids – pancake like things in stacks• Thylakoid space – inner space of the thylakoid• Grana – pancake stacks• Chlorophyll – green pigment found in thylakoids, AND, what makes

plants green

Photosynthesis

• Basically reverse of cellular respiration• Has light dependent and light independent (dark) reactions

• REMEMBER THIS…..

Light Dependent Reactions

• Converts solar energy into NADPH and ATP, more useable forms of energy• Occurs in the membranes of the thylakoids• Chlorophyll, the green pigment, absorbs sunlight, and causes some of

the electrons to be excited• Oxygen is released in this process• Check out the picture on the next slide

Light Dependent Reactions

Light Independent Reactions (aka Calvin Cycle)• Sometimes called the dark reaction, but this reaction does not need

to occur in the dark, it just doesn’t need light to occur• Takes place in the stroma of the chloroplast• Similar to the Krebs Cycle (see next slide)• Uses energy, ATP and NADPH from light-dependent reaction to run• Product is a three-carbon carbohydrate called glyceraldehyde-3-

phosphate (G3P), which can be used to make glucose or other carbohydrates

Light Independent Reactions (aka Calvin Cycle)

1. Grab: A five-carbon carbon catcher catches one molecule of carbon dioxide and forms a six-carbon molecule.2. Split: the enzyme RuBisCO (with the energy of ATP and NADPH molecules) breaks the six-carbon molecule into two equal parts.3. Leave: A trio of three carbons leave and become sugar. The other trio moves on to the next step.4. Switch: Using ATP and NADPH, the three carbon molecule is changed into a five carbon molecule.5. The cycle starts over again.(taken from http://simple.wikipedia.org/wiki/Calvin_cycle)

The Big Picture…