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Photosynthesis. An introduction. Class Brainstorm. Photosynthesis. The 5 Ws of Photosynthesis. Who? Photoautotrophs What? Use light energy and CO 2 to make sugars Where? Chloroplasts When? Need light Why? Source of energy for other organisms. Chlorophyll.
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Photosynthesis An introduction
Class Brainstorm Photosynthesis
The 5 Ws of Photosynthesis • Who? • Photoautotrophs • What? • Use light energy and CO2 to make sugars • Where? • Chloroplasts • When? • Need light • Why? • Source of energy for other organisms
Chlorophyll • Definition: A green colored pigment that absorbs light • Two types: Chlorophyll a (blue-green) and Chlorophyll b (yellow-green) • Consists of a porphyrinring and a long hydrocarbon tail • See page 139 for image
Porphyrin ring: a Mg atom at the centre and a hydrocarbon ring of alternating single and double bonds • Chlorophyll a has a methyl group (-CH3) • Chlorophyll b has an aldehyde group (-COH) • Hydrocarbon tail or Phytol tail: anchors molecule to a membrane
Eukaryotic Autotrophs • Algae, Photosynthetic Protists, and Plants • Chlorophyll in organelles: chloroplasts • Chloroplasts found in leaves (gives them green color)
Leaf Structure Waxy cuticle Upper Epidermis Palisade Mesophyll Spongy Mesophyll Mesophyll Vascular Bundle Lower Epidermis Guard Cells
Sketch and label a chloroplast • Inner and outer membrane • Stroma – protein-rich semi-liquid • Thylakoids– membrane bound sacs contain chlorophyll and ETC • Grana – stacks of thylakoids • Lamellae – unstacked thylakoids that connect grana • See page 144
Photosynthesis Overview • Step 1. Capture light energy. • Step 2. Make ATP and reduced NADP+ • Step 3. Make glucose and organic compounds.
Light • Electromagnetic radiation (EM): light is a form of energy • Visible light 380 (violet) -750 (red) nm • Travels in wave packets called photons
Absorption Spectrum: the wavelengths of light that a pigment will absorb • Action Spectrum: the most effective wavelength for photosynthesis • See page 152
Read “A Brief History of Photosynthesis Research” on page 149-150. • What experiment did J.B. Van Helmont conduct? What did he conclude? • What experiment did Joseph Priestly conduct? What did he conclude? • What is the source of O2 in photosynthesis?
Hmwk • Prelab for Fermentation Lab • Study for Quiz • Hmwk (take-up on Tues) • Qs: p145 #5b, 7, 9 • Qs: p154 #1, 3, 6, 7, 8