Cellular Respiration: Obtaining Energy from Food

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Cellular Respiration Obtaining Energy from Food

• Chapter 6
• Part I

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(No Transcript)
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• Muscles need energy to perform work
• Energy is obtained from glucose through reactions
  that require O2
• To keep moving muscles need a steady supply of O2

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Aerobic and Anaerobic Energy

• Aerobic O2 used by your cells to support their
  energy
• - as muscles work harder, you breathe faster and
  deeper to inhale more O2
• - demand for O2 outstrips bodys ability to
  deliver it
• Aerobic capacity max rate at which O2 can be
  taken in and used by your cells
• Anaerobic emergency mode breaks down glucose
  and produces lactic acid
• - lactic acid causes the burn, too much your
  muscles give out

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Feeling the Burn

• Physical conditioning allows your body to adapt
  to increased activity
• - the body can increase its ability to deliver
  O2 to muscles
• Long-distance runners wait until the final sprint
  to exceed their aerobic capacity

Figure 6.1
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Energy Flow and Chemical Cycling in the Biosphere

• Fuel molecules in food represent solar energy
• - energy stored in all food can be traced back
  to the sun
• Photosynthesis plants convert solar energy to
  chemical energy in the form of sugars and other
  organic molecules
• - animals depend on plants for this chemical
  energy
• - occurs mainly in green cells within the leaves
  of plants
• - chlorophyll is the green pigment molecule
  contained in chloroplasts (organelles that trap
  light energy)

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Autotrophs and Heterotrophs

• Autotrophs self-feeders
• - include plants and other organisms that make
  all their own organic matter from inorganic
  nutrients (CO2, water, and minerals from the
  soil)
• Heterotrophs other-feeders
• - organisms including humans and other animals
  that cannot make organic molecules from inorganic
  ones
• - depend on autotrophs for their organic fuel
  and material for growth and repair

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Producers and Consumers

• Producers biologists refer to plants and other
  autotrophs as the producers in an ecosystem
• Consumers heterotrophs are consumers
• - obtain their food by eating plants or other
  animals that have eaten plants
• - depend on food for fuel and the raw organic
  materials we need to build our cells and tissues

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Producer and Consumer

• Photosynthetic organisms use light energy to
  drive the production of their own organic
  material
• Animals depend on this photosynthetic product for
  their energy and building material

Figure 6.2
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Chemical Cycling between Photosynthesis and
Cellular Respiration

• The ingredients for photosynthesis are carbon
  dioxide (CO2) and water (H2O)
• - CO2 is obtained from the air by a plants
  leaves through tiny pores
• - H2O is obtained from the damp soil by a
  plants roots
• Chloroplasts rearrange the atoms of these
  ingredients to produce sugars (glucose) and other
  organic molecules
• - oxygen gas (O2) is a by-product of
  photosynthesis

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Cellular Respiration

• Plants have chloroplasts and are capable of
  producing fuel from sunlight
• - animals and plants use these organic fuel
  compounds to obtain energy
• Both plants and animals perform cellular
  respiration
• - a chemical process that harvests energy stored
  in sugars and other organic molecules
• - uses O2 to convert energy extracted from these
  organic fuels to the chemical energy, ATP
• - ATP is produced mainly in mitochondria
• The waste products of cellular respiration CO2
  and H20 are used in photosynthesis

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Energy flow and chemical cycling in ecosystems

• Energy enters as sunlight - exits in the form of
  heat
• Organisms temporarily trap the energy for their
  work
• Photosynthesis in chloroplasts of plants convert
  light energy to chemical energy
• Cellular respiration in the mitochondria harvest
  the food energy to generate ATP
• ATP drives most cellular work
• Chemical elements essential for life recycle
  between cellular respiration and photosynthesis

Figure 6.3
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Checkpoint

• Although they are self-feeders photosynthetic
  autotrophs are not totally self-sufficient. What
  chemical ingredients do they require from the
  environment in order to synthesize sugar?
• 2. Why are plants called producers? Why are
  animals called consumers?
• 3. What is misleading about the following
  statement? Plants perform photosynthesis,
  whereas animals perform cellular respiration.

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Answers

• Carbon dioxide and water also soil minerals
• Plants produce organic molecules by
  photosynthesis. Consumers must acquire organic
  material by consuming it rather than making it.
• It implies that cellular respiration does not
  occur in plants but it does.