Metabolism

METABOLISM  Biochemical processes in a living organism  Metabolism  Require energy

Proteins  Large, complex molecules  Critical roles in structure, function, and regulation of cells

ENZYMES  Proteins that speed up chemical reactions  Enzymes  They are not consumed  Enzymes that help build molecules  Anabolism  Enzymes that help break molecules bonds  Catabolism  Release energy

OXIDATION-REDUCTION REACTIONS  The removal of one of more electrons from molecule  Oxidation  The gain of one or more electrons from molecule  Reduction

PHOTOSYNTHESIS (PS)  Metabolism requires energy  Energy stored in molecules  ATP

PHOTOSYNTHESIS (PS)  Plants are solar powered  Photosynthesis  Chloroplasts

PHOTOSYNTHESIS (PS)  Produce sugar molecule from carbon dioxide and water  Oxygen is the byproduct

PHOTOSYNTHESIS (PS)  Air is composed of  78%  Nitrogen  21%  Oxygen  0.037%  Carbon dioxide  Oceans hold a significant amount

PHOTOSYNTHESIS (PS)  Carbon dioxide fertilization  Pumped into greenhouses  Increase yield 20%

PHOTOSYNTHESIS (PS)  Water  <1% of water absorbed by plants used in PS  Majority is transpired  Water is the source of electrons that drive the PS to create energy and sugar

PHOTOSYNTHESIS (PS)  Light  40% of sunlight is visible  Spectrum used by plants  Violet to blue  Red-orange  PS takes place in chloroplasts  Chlorophyll

PHOTOSYNTHESIS (PS)  Light-Dependent Reactions  Light strikes chlorophyll molecules  Water molecules split apart  Photolysis  Release electrons (power)  Hydrogen ions  Oxygen gas  Electrons passed along electron transport system  ATP molecules are produced  Energy molecules

PHOTOSYNTHESIS (PS)  Light-Independent  The Calvin Cycle  H ions from light-dependent PS arrive on NADPH molecule  H fixed to C from carbon dioxide  Form carbon molecules  Carbon molecules converted to glucose (sugar or carbohydrate)  PLANT FOOD  3-carbon molecule  C3 plants  4-carbon molecule  C4 plants

PHOTOSYNTHESIS (PS)  Light-Independent  The Calvin Cycle  C3 plants  Adapted to mild climate  Tolerate cold winters  C4 plants  Tropical or warm weather plants

PHOTOSYNTHESIS (PS)  CAM Photosynthesis  Crassulacean acid metabolism  Succulents  Desert plants  Similar to C4 plants  Most of the activity occurs at night when stomata are open  More efficient use of CO2  Conserve water

RESPIRATION  The release of energy from glucose  Growth and maintenance  Occurs 24 hours a day

RESPIRATION  Glycolysis  First major phase in respiration  Glucose converted to fructose  Addition of two phosphates  Fructose is split into two 3-carbon molecules

RESPIRATION  Glycolysis followed by either  Aerobic respiration  Most common  Anaerobic respiration

RESPIRATION  Aerobic respiration  The citric acid cycle (Krebs cycle)  Breaks down 3-carbon molecules from glycolysis  High-energy electrons are released for use in the plant

RESPIRATION  Aerobic respiration  The electron transport system receives electrons from citric acid cycle  Energy released along the way

RESPIRATION  Oxygen is the final receptor of electrons  Combine with hydrogen  Water  One glucose molecule yields 36 ATP molecules of energy

RESPIRATION  Anaerobic respiration  Lack of oxygen  Wet conditions  Not as efficient as aerobic respiration  Net gain of 2 ATP energy molecules

RESPIRATION Temperature  Respiration rates increase with temperature  >68F  Double or triple  Always respiring  Refrigerating fruit and vegetables  Lower respiration rate  Reduces microbial activity

RESPIRATION Water  Required for PS and respiration  Plant cells contain >90% water  Seeds contain <10%  Still respiring  Store in dry, cool area

CARBOHYDRATES  Glucose is a simple sugar  Used to produce carbohydrates  Longer, more complex molecules  Sucrose  Starch  Cellulose

ASSIMILATION  Use of carbohydrates to build cell walls and produce protoplasm  Assimilation

DIGESTION  Conversion carbohydrates into useable food  Digestion

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