Intro to Pigments & Photosynthesis

But first, a review. What is the point of cell respiration? These words all relate to cell respiration. How so? Catabolic Chemiosmosis Cytoplasm Cristae Redox reactions

What determines the direction taken? Where does it happen? Other products made? Where does it happen? What is it made of? Proton motive force - Where does it happen? What is the end product? Krebs Cycle ETC Glycolysis What determines the direction taken? Fermentation Where does it happen? Two kinds? -What’s the point?

Photosynthesis Essentially the reverse of respiration Capturing free energy Anabolic CO2 eventually reduced to sugar Endergonic Makes O2 from splitting of water

Obtaining Energy Autotroph vs. heterotroph Photoautotroph- photosynthesis Chemoautotroph- chemosynthesis

Chlorophyll Green pigment Embedded in thylakoid membrane Absorbs various wavelengths of light

Wavelengths of Light Red: Long wavelength. Around 700 nm. Violet: Shorter wavelength, higher energy Longer wavelength, lower energy Red: Long wavelength. Around 700 nm. Violet: Short wavelength. Around 400 nm.

Pigments for Photosynthesis Chlorophyll a (P680 and P700) Chlorophyll b Carotenoids Xanthophyll Each pigment has an absorption spectrum

Colors that are NOT absorbed are reflected- that’s the color we see

Chlorophyll a Best absorbs around 430 and 680 nm (violet/blue and red) Appears blue- green

Chlorophyll b Best absorbs around 450 and 640 nm (violet/blue and red/orange) Appears olive green

Carotenoids? Best absorbs around Appears

Food for thought So…green light is actually pretty terrible for photosynthesis. If you want to help your plants, give them more…? Fall colors (other pigments) appear when chlorophyll no longer produced

earthguide. uscd. edu: Absorption of EM Radiation http://earthguide Protons, electrons and the hydrogen atom Electron absorbs radiation of a specific wavelength Allows it to jump to a higher energy level- it’s excited Eventually emits the same amount of energy and “falls” to its “ground state” Measured with a spectrophotometer