Autotrophic Nutrition Topic 9

Autotrophic Nutrition Organisms manufacture own food Make organic compounds from inorganic compounds Plants, algae, some bacteria

Types of Autotrophic Nutrition Chemosynthesis- makes food from chemicals Photosynthesis- makes food from sunlight

Photosynthesis Occurs in chloroplasts Chloroplasts contain a green pigment- chlorophyll Chlorophyll traps sunlight

Chloroplasts Video: http://www.youtube.com/watch?v=LTglday5zak

Photosynthesis Equation 6 CO2 + 12 H2O → C6H12O6 + 6 O2 + 6 H2O Carbon Dioxide + Water → Glucose + Oxygen + Water

Inorganic Raw Materials (CO2 & H2O) Sunlight provides energy Enzymes are present in chloroplasts Organic Product (C6H12O6)

2 Reactions Take Place Light reaction occurs in the Grana Dark reaction occurs in the Stroma

Structure of a Chloroplast Dark reaction Light reaction

1. Photochemical Reaction (Light Reaction) Water & Sunlight absorbed Water is split- photolysis Oxygen released into atmosphere Hydrogen combines with NADP (an enzyme) temporarily

Photolysis – Water splitting

2. Carbon Fixation Reaction (Dark Reaction) Hydrogen and NADP split Hydrogen combines with CO2 CO2H2 becomes PGAL (a 3 carbon sugar) PGAL becomes Glucose (a 6 carbon sugar)

Where? Leaves (more surface area) A little in the stem

When? Photosynthesis- occurs during the day only! In plants only! In the chloroplasts! Respiration (opposite of photosynthesis)- occurs all the time, in all organisms, in the mitochondria.

Bill Nye- Discovery of Photosynthesis http://www.youtube.com/watch?v=pdgkuT12e14&feature=related

Wavelengths of Light Why is chlorophyll green? We see green because red and blue are absorbed and green is reflected. Red & blue are the best for photosynthesis.

Leaf Structure

Cuticle (cutin) Palisade Layer waxy covering protects from water loss filled with chloroplasts Most photosynthesis occurs here!!!!!!!!!!

Chloroplasts Xylem Phloem site of photosynthesis Transports water Transports food (glucose)

Guard Cell Stomate (pl.- stomata) Regulates the size of the stomate Some photosynthesis occurs here Stomate (pl.- stomata) Opening for gas exchange

Upper & Lower Epidermis Vein Bundle containing xylem and phloem Upper & Lower Epidermis Outer cell layer

Spongy Layer Mesophyll Below palisade layer Air pockets Some photosynthesis occurs here Mesophyll 2 layers: palisade and spongy

Structure of a Leaf

X – Stomate surrounded by guard cell – controls gas exchange

Images Chloroplasts- http://www.scar.utoronto.ca/~olaveson/A01F-Fall2007.html Photosynthesis- http://www.phschool.com/science/biology_place/biocoach/photosynth/overview.html Stoma: http://www.sparknotes.com/biology/plants/plantstructures/section4.rhtml Wavelengths: http://www.citruscollege.edu/lc/archive/biology/Pages/Chapter06-Rabitoy.aspx