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Metabolism
METABOLISM
 Biochemical processes
in a living organism
 Metabolism
 Requires energy to
operate
Proteins
 Large, complex molecules
 Critical roles in cell structure,
function, and regulation
ENZYMES
 Proteins that speed up chemical reactions
 Enzymes
 Enzymes 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
 Adenosine triphosphate
PHOTOSYNTHESIS (PS)
 Plants are solar powered
 Photosynthesis
 Chloroplasts
PHOTOSYNTHESIS (PS)
 Produces 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
of carbon dioxide
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 PS to
create energy and sugar
PHOTOSYNTHESIS (PS)
 Light
 40% of sunlight is visible
 Spectrum of light 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)
 Also release
 Hydrogen ions
 Oxygen gas
 Electrons passed along electron
transport system
 Energy molecules are produced
 ATP
 NADPH
PHOTOSYNTHESIS (PS)
 Light-Independent
 Also called the Calvin Cycle
PHOTOSYNTHESIS (PS)
 The Light-Independent System
(Calvin Cycle) receives from the
Light-Dependent System:
 Energy molecules
 ATP
 NADPH
 H-ions source
 Carbon dioxide introduced
 Carbon source
 Calvin Cycle produces glucose
 PLANT FOOD!
PHOTOSYNTHESIS (PS)
 Glucose is produced from either
3-carbon molecules or 4-carbon
molecules
 3-carbon molecule
 C3 plants
 Cool season plants
 4-carbon molecule
 C4 plants
 Warm season plants
PHOTOSYNTHESIS (PS)
 CAM Photosynthesis
 Crassulacean acid metabolism
 Succulents
 Desert plants
 Similar to C4 plants
 Most activity (metabolism) occurs
at night
 Stomata open at night, closed
during day
 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 is converted to fructose
 Addition of two phosphates
 Fructose is split into two 3-carbon
molecules
 Pyruvate
RESPIRATION
 Pyruvate (3-carbon
molecules) from glycolysis
goes to
 Anaerobic respiration
 OR
 Aerobic respiration
 Most common
RESPIRATION
Aerobic respiration
 The citric acid cycle (Krebs cycle)
 Breaks down pyruvate (3-carbon molecules) from glycolysis
 High-energy electrons are released as energy
RESPIRATION
Aerobic respiration
 The electron transport system
receives electrons from citric acid
cycle (Kreb’s Cycle)
 Energy production along the way
 ATP
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 rates double or triple
 Plants and fruit 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
 Carbohydrates are long complex
molecules
 Sucrose
 Starch
 Cellulose
ASSIMILATION
 Use of carbohydrates to build cell walls and produce protoplasm
 Assimilation
DIGESTION
 Conversion of insoluble carbohydrates, such as starch, into soluble food
sources the plant can use
 Digestion
 https://www.youtube.com/watch?v=iLDbW_XvxHQ
 https://www.youtube.com/watch?v=q_fZtJMMLPE