Photosynthesis and Cellular Respiration

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Chapter 4

• Photosynthesis and Cellular Respiration

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Chapter Objectives

• Explain how energy is stored and released during
  the ATP cycle

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• Contrast the ways autotrophs and heterotrophs
  obtain food
• Identify the substances and structures involved
  in photosynthesis

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• Compare the steps of photosynthesis that require
  light to the steps that do not
• Explain how cellular respiration releases energy
  from food

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• Compare aerobic and anaerobic respiration
• Summarize the flow of food and energy in the
  biosphere

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Section 4.1Energy and ATP

• Key words
• ATP
• Autotrophs
• Heterotrophs

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The BIG Idea

• All organisms get energy by breaking down the
  chemical compounds in foods and making ATP and
  other molecules

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Review questions

• What is a molecule?
• Answer Two or more atoms covalently bonded
  together

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Review question

• What holds the elements together in a compound?
• Answer Chemical bonds

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Wheres the energy?

• Life is fueled by the energy contained in
  chemical bonds of compounds like ATP, NADH,
  NADPH AND FADH2

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ATP Energy for Life

• ATP (adenosine triphosphate) is the most
  important energy-storing compound in organisms

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ATP

• Consists of three parts
• Ribose (a 5-carbon sugar)
• Adenine
• Phosphates

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ATP - A Nucleotide
base
three phosphate groups
sugar
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Adenosine?

• Aden os ine
• Aden-ine rib(os)e

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Triphosphate

• Three phosphate molecules are bonded to the
  adenosine

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ATP ADP P

• Breaking the bond between the second and third
  phosphates releases energy for use by the cell

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ADP P ATP

• Forming the bond between the second and third
  phosphates stores energy for use by the cell

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Uses for ATP energy

• Three main types of biological work
• Mechanical functions, e.g. moving flagella or
  muscles contracting

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• Active transport of ions and molecules across the
  cell membrane

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• Used to synthesize (make) or break down large
  molecules

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ATP Energy for Life

• Making and breaking ATP occurs continuously in
  cells,
• Up to 10 million new ATP molecules are formed
  each second in every cell

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Sources of Energy

• Organisms are classified as either autotrophs or
  heterotrophs based on how they obtain food

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Autotrophs

• Those organisms that can make their own food are
  autotrophs (self feeders)
• Include plants, algae and some bacteria

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Autotroph Producers

• Autotrophs produce food for themselves and other
  organisms
• Food is mainly carbohydrates like glucose

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Thermal Vent Bacteria

• Not all autotrophs depend on the sun for energy
• Bacteria near volcanic vents in the deep sea use
  energy from inorganic compounds to produce food

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Thermal-ventBacteria
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Heterotrophs

• Organisms that cant make their own food are
  heterotrophs (other feeders)

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Heterotrophs

• Animals, fungi and many unicellular organisms
  rely on autotrophs or other heterotrophs for food
• Known as consumers

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