Essay by pacoHigh School, 10th gradeA+, January 1997

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General Info

Defn: 'To make with light'

Reactants (Ingredients)

CO2, H2O, Sunlight, chlorophyll


Food (C6H12O6 = glucose) and O2

Overall Reaction

Photosynthesis is actually a series of two reactions.

Light reactions (require sunlight)

chlorophyll uses sunlight to split water and form oxygen and chemical energy.

Dark reactions (don't require light)

use chemical energy from light reaction to convert carbon dioxide into glucose.

Where does photosynthesis take place?

Structure of a Chloroplast



chlorophyll absorbs red, orange, blue and violet, and use the energy of light to do work.

The light reactions

occur on the surface of the thylakoid membrane.

The chemistry of light reactions

Dark reactions

occurs in the stroma

also called the, 'Calvin-Benson Cycle'

The energy to do all this work comes from the light reactions.

Chemistry of dark reactions

Overall reaction combining separate light and dark reaction equations.


General Info

Definition: Breaking down food (glucose) to get energy.

Every step of this pathway is controlled by enzymes.

Overall Chemical Equation:

Glucose is broken down and energy is formed in a three step process.


Glucose broken down to form 2 three carbon molecules

Kreb's Cycle

three carbon molecules are broken down to 3 carbon dioxide molecules

Electron Transport

protons generated in two previous steps are with oxygen to make water and ATP.

Glycolysis (nine step process)

Takes place in the cytoplasm of a cell.

Doesn't require oxygen.

2 ATP are needed to begin this reaction, but 4 ATP are made, therefore 2 ATP is the net yield.

Glucose (6-carbon) is broken down into 2 pyruvic acid molecules (3-carbon).

Chemical Overview

If oxygen levels are still low, there are two options:

In mammals:

In yeast and bacteria:

If oxygen is available then pyruvic acid enters the Kreb's Cycle.

Kreb's Cycle

Takes place...