Bioenergetics

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Bioenergetics
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• The Big Picture
• - energy flows through
• - matter recycles

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• Producers Autotrophs
• - organisms which can make their food
• - plants, algae, some bacteria
• - most use photosynthesis
• Consumers Heterotrophs
• - organisms which get their food from other
  organisms
• - animals, fungi, most protists
• - most use cellular respiration
• ATP Adenosine triphosphate
• - normal molecule that cells use to store and
  release energy
• - used to power all cellular work

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• - stores small amounts of usable energy
• - cells must recycle it quickly
• Photosynthesis
• - process by which plants use the energy of
  sunlight to convert water and carbon dioxide
  into high-energy carbohydrates (sugars carbs)
  and oxygen (a waste product)
• 6CO2 6H2O ---light--gt C6H12O6 6O2
• carbon dioxide water ---light--gt sugars
  oxygen
• - chlorophyll is the primary light-gathering
  pigment of plants
• - chlorophyll reflects green light

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See diagram page 209 in text
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• Photosynthesis happens in mesophyll cells of a
  leaf.
• - contain chloroplasts which have thylakoids
  where reactions occur
• - two sets of reactions
• 1. Light-dependent reactions
• 2. Light-independent reactions Calvin cycle
• Light-dependent reactions
• - require light
• - happen in photosystems on thylakoid membranes
• - sunlight splits water into H and O2
• - also forms ATP and NADPH
• -NADPH carries electrons (energy) to Calvin cycle

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• - excited electrons from photosystems give energy
  to pump H into thylakoid spaces and then form
  ATP

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See diagram on page 211 of textbook.
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• - a concentration gradient of H in thylakoids is
  balanced by diffusion through ATP synthase
• Light-Independent Reactions Calvin Cycle
• - occur in the stroma of the chloroplast
• - use the ATP and NADPH from the light reactions
  to convert CO2 into C6H12O6
• - six CO2 are needed to make one sugar molecule

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• Cellular Respiration Ch. 9
• - the energy captured in photosynthesis is
  released by organisms by several chemical
  pathways
• - breaks down glucose and other food molecules in
  the presence of oxygen
• 6O2 C6H12O6 6CO2 6H2O Energy
• Oxygen glucose carbon dioxide
  water energy
• - energy of food is measured in calories
• - food Calorie 1 kilocalorie (1,000 calories)
• - energy of food must be released slowly and
  captured in the bonds of ATP

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See page 222 in textbook
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• Glycolysis
• - breaks a molecle of glucose into two pyruvic
  acids
• - occurs in the cytoplasm of all cells with or
  without oxygen
• - net gain of 2 ATP not much, but very fast
• - also produces 2 NADHs which carry electrons
  and H to other reactions in the cell
• Fermentation
• - when oxygen is not available fermentation
  occurs
• - yeasts and a few other organisms form alcohol
• - in our muscles fermentation forms lactic acid

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• Krebs Cycle Citric Acid Cycle (pg. 227)

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• Krebs Cycle Citric Acid Cycle
• - in the presence of oxygen, pyruvic acids are
  modified and taken into the mitochondria
• - capture energy from bonds of pyruvates to form
  ATP, NADH, and FADH2
• - occurs in mitochondrial matrix
• - releases CO2
• Electron Transport Chain (pg. 228)
• - NADH and FADH2 from glycolysis and Krebs Cycle
  carry electrons (energy) to electron transport
  chains on inner membrane of mitochondria
• - movement of electrons through E.T.C. pumps H
  into outer compartment of mitochondria to
  establish a concentration difference

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• - H can only diffuse out through ATP synthase
  and the energy of their diffusion is used to form
  ATPs

See page 228
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Summary of ATP production in Cellular Respiration
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