PHOTOSYNTHESIS AND CELLULAR RESPIRATION

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PHOTOSYNTHESIS AND CELLULAR RESPIRATION

• Chapter 5

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ENERGY AND LIVING THINGS

• Metabolism involves either using energy to build
  molecules or breaking down molecules in which
  energy is stored
• PHOTOSYNTHESIS - the process by which light
  energy is converted to chemical energy

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• AUTOTROPHS organisms that use energy from
  sunlight or from chemical bonds inorganic
  substances to make organic compounds
• Some prokaryotes use chemosynthesis to produce
  organic compounds

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• HETEROTROPHS organisms that must get energy
  from food instead of directly from sunlight or
  inorganic substances
• CELLULAR RESPIRATION a metabolic process
  similar to burning fuel, but it converts food
  energy to ATP
• ATP provides cells with the energy needed to
  carry out the activities of life

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• Chemical energy stored in food is released
  gradually
• The product of one chemical reaction becomes a
  reactant in the next reaction
• Some of the energy is released as heat, but the
  remaining energy is stored as ATP portable form
  of energy
• Adenosine triphosphate

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• Complete sentences
• P.96 section review 1-6
• P. 112 5a,6,12

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PHOTOSYNTHESISsection 2

• Using the Energy in Sunlight

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• About 1 of the energy in the sunlight is
  converted to chemical energy
• Three stages of Photosynthesis
• Stage 1 Energy is captured from sunlight.
• Stage 2 Conversion of Light Energy
• Stage 3 Storage of Energy

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Stage 1Absorption of Light Energy

• First second stages are sometimes called light
  reactions
• Light is a form of radiation energy in the form
  of waves
• Pigments absorb only certain wavelengths and
  reflect all the others
• Chlorophyll absorbs mostly blue red lights

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• Plants contain two types of chlorophyll, a and b,
  a being the most important
• Carotenoids pigments that produce yellow
  orange colors absorb wavelengths of light
  different from chlorophyll

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Production of Oxygen

• Thylakoids-located in the chloroplasts contain
  the pigments necessary for photosynthesis
• Light energy is transferred to electrons causing
  them to be excited

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• Electrons jump to other molecules where they are
  used to power the second stage
• Replacement electrons come from water molecules
• Water molecules are split by enzymes, leaving H
  ions, and O atoms, forming Oxygen gas,

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Stage Two Conversion of Light Energy

• Electron Transport Chains (2)- series of
  molecules through which excited electrons are
  passed along a thylakoid membrane
• Provides the energy needed to change ADP to ATP

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• A second electron transport chain provides
  energy used to make NADPH
• NADPH electron carrier that provides the
  high-energy electrons needed to make
  carbon-hydrogen bonds in the third stage
• Excited electrons combine with hydrogen ions
  NADP to form NADPH

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Stage Three Storage of Energy

• CARBON DIOXIDE FIXATION transfer of carbon
  dioxide to organic compounds
• Considered light-independent dark reactions
• Most common method is the Calvin cycle
• Calvin cycle- a series of enzyme-assisted
  chemical reactions that produces a 3-C sugar

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• The reactions are cyclic they recycle the
  five-carbon compound needed to begin the cycle
  again
• The energy used in the Calvin cycle is supplied
  by ATP and NADPH made during the second stage of
  photosynthesis

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Factors that Affect Photosynthesis

• Light photosynthesis increases as light
  intensity increases until all the pigments are
  being used limited by Calvin reaction which is
  the slowest step
• Carbon dioxide concentration once a certain
  concentration is reached photosynthesis is
  limited
• Temperature- certain range is more efficient

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• Water the availability of water and the amount
  of rainfall
• Nutrients how much organic matter that soil
  contains

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• P. 103
• Section 2 review 1-6
• P. 112 1,2,3, 5c,8,9
• Standardized Test Prep 1-3

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Cellular Respiration

• Food contains usable energy in the form of
  protein, fat, carbs
• Energy has to be transferred to ATP, which is
  done through cellular respiration
• AEROBIC respiration- metabolic processes that
  require oxygen, more efficient in making ATP
• ANAEROBIC-metabolic processes that do not require
  O2

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Stages of Cellular Respiration

• Stage I Breakdown of Glucose
• Stage II Production of ATP

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Stage I Breakdown of Glucose

• Glycolysis takes place in the cytoplasm- an
  enzyme-assisted anaerobic process that breaks
  down one 6-C molecule of glucose to 2 3-C pyruvic
  ions
• 4 Steps in the series on page 105 you can copy
  them from the book
• Glycolysis uses two ATP but produces four ATP

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Stage Two Production of ATP

• Krebs Cycle enzyme-assisted reactions named for
  Hans Krebs, 1937
• 5 steps on p. 106 107
• Much of the energy that was stored in glucose
  pyruvate is now stored in NADH and FADH2

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Electron Transport Chain

• The electron transport chain pumps hydrogen ions,
  H, out of the inner compartment.
• At the end of the chain, electrons hydrogen
  ions combine with oxygen, forming water.
• ATP is produced as hydrogen ions diffuse into the
  inner compartment through a channel protein.

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Respiration in the Absence of Oxygen

• Electron transport chain does not function if
  oxygen is not available as final electron
  acceptor.
• Electrons in NADH are transferred to pyruvate
  enables the recycling of NAD which is needed to
  make ATP
• Fermentation- recycling of NAD using an organic
  hydrogen acceptor

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Lactic Acid Fermentation

• Pyruvate is converted to lactate
• Lactate is the ion of lactic acid
• Vigorous exercise muscles must operate without
  enough O2
• ATP produces only while glucose supply lasts
• Blood removes excess lactate, but if not
  quickly-can cause muscle soreness

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Alcoholic Fermentation

• Two step process
• Pyruvate is converted to 2-C compound, releasing
  CO2
• Electrons are transferred from NADH to the two-C
  compound, producing ethanol
• Yeast, a fungus, uses alcoholic fermentation.
  Yeast is used in bread industry and alcoholic
  beverages
• Ethanol (12) kills yeast

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Production of ATP

• Total of ATP produced from glucose depends on the
  absence or presence of O2
• 2 ATP molecules are made during the Krebs cycle
• 34 ATP are produced by the electron transport
  chain

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Homework

• Page 110 - section review 1-6
• Page 112 3,4, 5b, 5d,7,10,13,14,19
• Test Part 2 over section 3 Monday 8th
• 10 true false 14 multiple choice and discussion