Photosynthesis Intro Chapter 8

What you need to know! How photosystems convert solar energy into chemical energy

Chloroplasts

Thylakoid Membrane has Pigment Molecules imbedded within Photosystems 1 & 2 Chlorophyll a, b, carotenoids, and xanthophylls Electron transport chain molecules ATP Synthase

Structure of Chlorophyll Expensive molecule: is recycled in fall in temperate climates Magnesium center Chlorophyll has a hydrocarbon tail to make it lipophilic for membrane attachment

Physics of Light Light (like all radiation) has energy Radiation can be sorted into an electromagnetic wave spectrum according to its wavelength ROY G BIV

Chlorophyll Absorbance Chlorophyll a and b absorbance spectrums for both pigments maximize absorbance in the… What light is reflected?

Leaf Structure and Photosynthesis Photosynthesis takes place in the mesophyll CO2, O2, & H2O (water vapor) will diffuse through stomata Stomata must be open for photosynthesis Only turgid stomata cells are open; if they become flaccid, they close Cuticle Mesophyll Vein Cuticle Stoma (stomata = plural)

Paper Chromatography Technique for separating and identifying pigments from cell extracts. The solvent moves up chromatography paper by capillary action Pigments (solutes) are dissolved in the solvent and are carried up the paper

Paper Chromatography Differing pigments have different properties: Solubility, size/shape, polarity Different bands form as the solutes separate while they migrate up the paper

Rf Values of Pigments Rf is a ratio of the migration of the pigment (B) over the migration of the solvent (F) Rf = B/F B = distance (mm) from the bottom of the pigment origin to the bottom of the pigment migration If more than one pigment molecule is tested the highest band is B1, the next band is B2, etc. F = distance from the bottom of the pigment origin to the bottom of the solvent front

Rf Values of Pigments Solvent Front B4 Band # Distance migrated Rf value Identification of substance 1 2 B4 Rf values of substances are specific to the chromatography system used. If paper or solvent is changed, Rf values change Rf values do not change with migration length in a system Rf values are always between 0 & 1 B3 B2 B1 Pigment Origin