Photosynthesis All living organisms can be divided into

Photosynthesis

All living organisms can be divided into two main groups

Heterotrophs “consumers” Organisms that cannot use the sun’s energy to make food Obtain energy by consuming plants and other animals Ex: animals and most microorganisms

Autotrophs “producers” Use light energy from the sun to produce food Produce glucose and other carbohydrates Ex: Plants

Photosynthesis The process by which the energy of sunlight is converted into the energy of glucose. Converts water and carbon dioxide to glucose and oxygen Performed by autotrophs such as green plants and some bacteria

Photosynthesis Net Equation 6 CO 2 + 6 H 2 O Carbon dioxide + Water Light energy Enzymes and Chlorophyll C 6 H 12 O 6 + 6 O 2 Glucose + oxygen

Carbon Fixation Converts inorganic carbon found in carbon dioxide to organic carbon in glucose.

Photosynthesis’ Purpose Trap the sun’s energy and store it as glucose (food for the plant)

Photosynthesis occurs in the chloroplasts of the cell.

Chloroplast Structure

Chlorophyll The pigment inside the chloroplast that absorbs light for photosynthesis.

As the chlorophyll in leaves decays in the autumn, the green color fades and is replaced by the oranges and reds of carotenoids.

Steps of Photosynthesis 1. Light Dependent Reaction 2. The Calvin Cycle

Light H 2 O Reactants CO 2 NADP+ ADP + P Light Dependent Reaction ATP Calvin Cycle NADPH Chloroplast O 2 C 6 H 12 O 6 Glucose Products

Light Dependent Reactions Requires light Electrons in the chlorophyll absorb the light energy Energy from the electrons converts ADP to ATP Water molecules are split to form oxygen, hydrogen ions, and electrons Hydrogen ions attach to carrier molecules to be used in later steps of photosynthesis

Light Dependent Reactions During this stage the carrier molecule NADP becomes NADPH when the hydrogen ions attach to the carrier molecules.

Light Independent Reactions Aka The Calvin Cycle Does NOT require light Carbon dioxide and hydrogen ions combine to form simple sugars. Simple sugars can be stored as complex carbohydrates such as cellulose and starch.

The Calvin Cycle CO 2 + Carbon Dioxide H+ Hydrogen Ions Enzymes And ATP C 6 H 12 O 6 glucose

Complex Carbohydrates If more glucose is made than the plant needs, then it is stored as complex carbohydrates Ex: cellulose and starch Needed for development and growth If eaten by another organism, the organism breaks the chemical bonds in the carbohydrate molecules (cellular respiration) and energy is released for that organism’s use.