Photosynthesis and Cellular Respiration

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PHOTOSYNTHESIS and RESPIRATION
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SECTION 1

• Photosynthesis

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Energy and Living Things

• Photosynthesis is the process in which light
  energy is converted into chemical energy.
• Autotrophs (plants and some bacteria) use the
  suns energy to carry out photosynthesis, and are
  therefore the foundation of all living systems.

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Breaking Down Food For Energy

• Autotrophs are organisms that use energy from
  sunlight or from chemical bonds in inorganic
  substances to make organic compounds.
• Heterotrophs are organisms that must consume
  other organisms as food to get their energy.

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Photosynthesis

• Photosynthesis is the process by which plants,
  algae, and some bacteria use sunlight, carbon
  dioxide, and water to produce carbohydrates and
  oxygen.
• Photosynthesis has 3 stages
• Stage 1 absorption of light energy
• Stage 2 conversion of light energy into
  chemical energy, temporarily stored in ATP and
  NADPH
• Stage 3 storage of chemical energy in ATP and
  
• NADPH powers the formation of organic
  molecules

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Photosynthesis

• Pigments are light-absorbing substances that
  absorb only certain wavelengths of light and
  reflect all others.
• Chlorophyll is the primary pigment involved in
  photosynthesis. Chlorophyll absorbs mostly blue
  and red light and reflects green and yellow
  light.
• This reflection of green and yellow light makes
  many plants, especially their leaves, look green.

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• Photosynthesis occurs in the chloroplasts and
  uses the pigment chlorophyll.

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Photosynthesis

• The following chemical equation summarizes
  photosynthesis
• 6H2O 6CO2 light ? C6H12O6 6O2
• REACTANTS water, carbon dioxide, light energy
• PRODUCTS glucose, oxygen

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Photosynthesis Where Does it Occur?
Thylakoid membrane
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Photosynthesis Thylakoids

• Thylakoids are disk-shaped structures found in
  the chloroplasts of leaf cells that contain
  clusters of embedded pigments.
• These pigment molecules in the thylakoids of
  chloroplasts absorb light energy.
• Electrons in the pigments are excited by light,
  and jump from the chlorophyll molecules to other
  nearby molecules in the thylakoid membrane.
• The series of molecules along the thylakoid
  membrane that excited electrons pass through as
  they jump along the chlorophyll molecules is
  called the electron transport chain.

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Three Factors That Affect Photosynthesis

• 1.) amount of light The rate of photosynthesis
  increases as light intensity increases until all
  the pigments are being used. At this saturation
  point, the reactions of the Calvin cycle cannot
  proceed any faster.
• 2.) concentration of carbon dioxide Once a
  certain concentration of carbon dioxide is
  present, photosynthesis cannot proceed any
  faster.
• 3.) range of temperature Like all metabolic
  processes, photosynthesis involves many
  enzyme-assisted chemical reactions. Unfavorable
  temperatures may inactivate certain enzymes.

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SECTION 2

• Cellular Respiration

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Cellular Respiration

• Before energy from food can be utilized, it must
  be transferred to ATP in a process called
  cellular respiration.
• Cellular respiration is the set of metabolic
  reactions and processes that take place in the
  cells of organisms to convert biochemical energy
  from nutrients into adenosine triphosphate (ATP),
  and then release waste products.
• To put it simply, cellular respiration is the
  process where cells produce energy from
  carbohydrates.

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Cellular Respiration

• Cellular respiration is the opposite of
  photosynthesis.
• The reactants of photosynthesis carbon dioxide
  and water are the products of cellular
  respiration.
• The products of photosynthesis glucose and
  oxygen are the reactants of cellular
  respiration.
• Cellular respiration releases much of the energy
  in food to make ATP.
• ATP provides cells with energy they need to carry
  out the activities of life.

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Cells Transfer Energy From Food To ATP

• When cells break down food molecules, some of the
  energy is released into the atmosphere as heat,
  while the rest is stored temporarily in molecules
  of ATP.
• Adenosine triphosphate (ATP) is a nucleotide with
  two extra energy-storing phosphate groups.
• ATP molecules are often called the energy
  currency of a cell.

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Adenosine Triphosphate
RED ribose (a 5-carbon sugar)BLUE adenine
(a nitrogenous base)GREEN phosphate groups
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ATP Stores and Releases Energy

• The energy from ATP is released when the bonds
  that hold the phosphate groups together are
  broken.
• The removal of a phosphate group from ATP (3
  phosphates) produces ADP (adenosine diphosphate
  -- 2 phosphates), which releases energy in a way
  that enables cells to use the energy.
• Cells use energy released by this reaction to
  power metabolism.

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• ATP FYI
• The human body uses about 1 million molecules of
  ATP per second per cell.
• There are more than 100 trillion cells in the
  human body.
• That is about 1 X 1020, or 100,000,000,000,000,000
  ,000 ATP molecules used in the body each second.

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• Cellular respiration can be aerobic respiration
  (with oxygen) or anaerobic respiration (without
  oxygen).
• Cellular respiration begins in the cytoplasm, and
  ends in the mitochondria.

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Aerobic Respiration

• Respiration that requires oxygen to form energy.
• Cardio exercises, which involve maintaining a
  steady heart rate at 60-80 of ones maximum, use
  aerobic respiration because there is enough
  oxygen to sustain muscle power. Sports activities
  that use aerobic metabolism include distance
  running, swimming, biking, and jogging.

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Anaerobic Respiration

• Respiration that does not require oxygen to
  produce energy.
• Intense workouts and sports activities that use
  much energy within short bursts of activity
  usually require anaerobic respiration, which
  provides an immediate source of power. This
  process is needed especially in activities that
  increase the heart rate beyond 80 of its
  maximum. Examples of anaerobic sports include
  football, sprinting and wrestling

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Cellular Respiration

• The chemical formula for cellular respiration is
• C6H12O6 6O2 ADP P ? 6CO2 6H2O ATP
• REACTANTS glucose, oxygen, ADP, extra phosphate
• PRODUCTS carbon dioxide, water, ATP
• The process summarized by the equation begins in
  the cytoplasm of a cell and ends in the
  mitochondria.

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Cellular Respiration Stage 1 Glycolysis

• Stage 1 of cellular respiration is called
  glycolysis.
• Glycolysis is the stage of cellular respiration
  where glucose is broken down in the cytoplasm,
  converted to pyruvate, and produces a small
  amount of ATP and NADPH.
• Glycolysis uses 2 ATP, but produces 4 ATP net
  gain 2 ATP

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Cellular Respiration Stage 2The Krebs Cycle

• Stage 2 of cellular respiration is known as the
  Krebs cycle and is also called aerobic
  respiration.
• Cellular respiration is called an aerobic process
  because it requires oxygen.
• C6H12O6 6O2 ADP P ? 6CO2 6H2O ATP
• A two-carbon molecule combines with a four-carbon
  molecule during the Krebs cycle.

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FermentationOccurs in the Absence of Oxygen

• If oxygen (O2) is not present in sufficient
  amounts, the mitochondrial membrane cannot
  function.
• Energy molecules (ATP and NADH) cannot be created
  in abundance.
• So, what does the cell do to continue to break
  down organic compounds and release energy if not
  enough oxygen is present?
• FERMENTATION

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Production of ATP

• The total amount of ATP a cell is able to harvest
  from each glucose molecule that enters glycolysis
  depends on the presence or absence of oxygen.
• When oxygen is present, aerobic respiration
  occurs.
• When oxygen is not present, anaerobic
  respiration, or fermentation, occurs instead.
• Fermentation is the anaerobic process that
  continues the breakdown of carbohydrates when
  there is not enough oxygen for aerobic
  respiration.

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