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
 https://www.youtube.com/watch?v=YeD9idmcX0w
 https://www.youtube.com/watch?v=wJDlxp17rY4