PHOTOSYNTHESIS

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PHOTOSYNTHESIS

• CAPTURING ENERGY
• Chapter 6

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ENERGY

• Autotrophs Organisms that make their own food
  from inorganic substances and energy (ATP).
• Use photosynthesis converting light energy into
  chemical energy
• Store chemical energy as organic compounds (like
  carbohydrates)
• EX plants, algae, and some bacteria

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PHOTOSYNTHESIS6CO26H2Olight C6H12O66O2

• A biochemical pathway that involves a complex
  series of chemical reactions
• Process supports virtually all life on Earth

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Understanding Photosynthesis

• 1. Jan Van Helmont (17th century) set up an
  experiment to understand how a small seed grew to
  a large tree
• Concluded that plants need water to grow.
• 2. Joseph Priestly (100 years later) set up an
  experiment with a candlehe discovered a candle
  in a jar died out but a candle in a jar with a
  plant continued burning.
• 3. Jan Ingenhousz found that the plant/candle
  experiment only worked when the plant was exposed
  to sunlight
• Concluded light is necessary for plants to
  produce oxygen

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The Nature of Light

• Visible Spectrum the separation of white light
  into different colors (wavelengths)
• PIGMENT a molecule that absorbs certain
  wavelengths of light and reflects or transmits
  others

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Chloroplasts- organelle that contains chlorophyll
and other pigments site of
photosynthesis

• Contains
• Thylakoids disk-shaped structures that contain
  photsynthetic pigments
• Grana Stacks of thylakoids (resemble stacks of
  pancakes)
• Stroma Solution surrounding the thylakoids
• Chlorophyll- light collecting pigment located on
  the thylakoid disks

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CHLOROPHYLL and PIGMENTS

• The most common and important photosynthetic
  pigments in plants and algae.
• Absorbs violet, blue, and red lights.
• Reflect and Transmit Green light giving plants
  their GREEN color.
• Chlorophyll a primary photosynthetic pigment
• Accessory Pigments Chlorphyll b and carotenoids

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LIGHT REACTIONS

• Initial reactions of photosynthesis
• Begins with absorption of light in chloroplasts
  (in the thylakoids)
• Produces NADPH (energy carrier), ATP, H
  needed in the Calvin Cycle to make FOOD

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Light rxn.
Animation
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Light rxn. Cont.

• Reactants H2O Sunlight
• Products O2 ATP NADPH H
• (used later)

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Chemiosmosis

• The synthesis of ATP
• Occurs when there is a concentration gradient of
  protons across the thylakoid membrane
• ADP ? ATP

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CALVIN CYCLE

• Second set of reactions in photosynthesis
• Produces organic compounds using energy from ATP
  NADPH made in the light reactions.
• Occurs in the stroma
• (liquid area of the chloroplast)

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Calvin cycle cont.

• Is not dependent on light!
• Occurs when ATP and NADPH are present
• Makes stored energy (in the form of carbs.) the
  plant can use

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How is this done?

• Carbon fixation carbon atoms are bonded
  (fixed) into organic compounds
• Reactants CO2 ATP NADPH H
• Products O2 C6H12O6

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Animation
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The rate of photosynthesis varies

• 1. light intensity
• 2. amount of CO2
• 3. temperature

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ALTERNATIVE PATHWAYS

• STOMATA small pores in leaves of plants
• C4 Plants close stomata during hot parts of the
  day (still able to produce carbohydrates)
• Include corn, sugar cane, and crabgrass
• CAM Plants open stomata at night and close them
  during the dayproducing organic compounds at
  night
• EX cactuses, pineapples

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Notebook quiz

• Write the equation for photosynthesis out in
  words?
• Where in the chloroplast do the light reactions
  occur?
• What are the products of the light reaction?
• What are the products of the Calvin Cycle?
• What is the primary photosynthetic pigment in
  plants?

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CELLULAR RESPIRATION

• MAKING ENERGY

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CELLULAR RESPIRATION

• C6H12O6 6O2 6CO26H2O energy
• The complex process in which cells make ATP by
  breaking down organic compounds
• HETEROTROPHS Organisms that obtain energy from
  eating autotrophs or other heterotrophs

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GLYCOLYSIS

• The beginning of cellular respiration
• A biochemical pathway that produces very little
  ATP
• With Oxygenglycolysis is followed by AEROBIC
  RESPIRATION to produce more ATP
• Examples of aerobic exercise long distance
  activities
• Without Oxygenglycolysis is followed by
  FERMENTATION (anaerobic respiration) producing no
  ATP
• Examples of anaerobic exercise sprinting

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GLYCOLYSIS (cont.)

• Organic Compounds
• Glycolysis ATP
• no Oxygen with Oxygen
• Fermentation Aerobic
• (anaerobic Respiration
• ATP

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GLYCOLYSIS PRODUCTION

• Glycolysis USES 2 ATP molecules to start the
  pathway
• Glycolysis MAKES 4 ATP molecules at the end of
  glycolysis
• Therefore Glycolysis
• PRODUCES A TOTAL OF 2 ATP
• NADH
• 2 molecules of Pyruvic Acid

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FERMENTATION

• Without OxygenGlycolysis goes to Anaerobic
  Respiration
• Does not produce ATP
• Does produce molecules that can be used in other
  processes to produce ATP
• 2 most common fermentation pathways
• LACTIC ACID FERMENTATION
• ETHYL ALCOHOL FERMENTATION

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LACTIC ACID FERMENTATION

• Helps produce some foods, ex) yogurts and
  cheeses
• Also occurs in your muscle cells during very
  strenuous exercisesuch as sprinting at top
  speeds
• As lactic acid accumulatesit reduces the ability
  of the muscle cells to contractresulting in
  fatigue, pain, and cramping

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ALCOHOLIC FERMENTATION

• Used by some plant cells and unicellular
  organisms
• Used in the wine and beer industries and in the
  making of breads.

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AEROBIC RESPIRATION

• Occurs when Oxygen is present in the cell
• Produces more ATP (nearly 20 times as much as is
  produced by glycolysis alone
• Takes place in the mitochondria
• 2 major stages
• The Krebs Cycle
• Electron Transport Chain

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THE PRODUCTION OF ATP
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THE KREBS CYCLE

• Occurs in the mitochondrial MATRIX (space inside
  the inner membrane of the mitochondria)
• Biochemical pathway that breaks down acetyl CoA,
  and produces CO2, hydrogen atoms, and ATP
• 1 Glucose molecule gives 2 cycles of the Krebs
  cycle and produces
• 6 NADH
• 2 FADH2
• 2 ATP
• 4 CO2

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ELECTRON TRANSPORT CHAIN

• Second stage of aerobic respirationoccurs along
  the many folds (cristae) of the mitochondria
• 4 NADH from Glycolysis produce a total of 12
  ATP
• 6 NADH from Krebs produce a total of 18 ATP
• 2 FADH2 from Krebs produce a total of 4 ATP
• Electron Transport Chain Produces a TOTAL of 34
  ATP

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CELLULAR RESPIRATION

• THE ENTIRE PROCESS CAN PRODUCE A TOTAL OF 38 ATP

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Why do leaves change color in the fall?

• How do annuals and perennials survive winter?
• Why do deciduous trees loose their leaves and
  evergreens do not loose their needles?
• Why do the leaves fall from the trees in autumn?
• How and why do the leaves separate from the tree?
• What is anthocyanin?
• Name other pigments that appear in leaves after
  the chlorophyll disappears.
• Where is the best place to see the color change?
  Why?

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• Photosynthesis Comic Directions
• Create a minimum 6 slide comic strip summarizing
  the process of photosynthesis. Be sure to
  include the reactants and products of the light
  and dark reactions.

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Cellular Respiration Poster!

• Design a poster summarizing all important parts
  of the stages of aerobic and anaerobic cellular
  respiration.
• Show how all of the processes are related
• Be creative
• Be prepared to show your poster to the rest of
  the class and explain its contents

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Notebook Quiz

• Distinguish between autotrophs and heterotrophs.
• What are the (3) products of glycolysis?
• After glycolysis, what determines the next step?
• What type of fermentation occurs in animal cells?
• What are the 2 steps of aerobic respiration?
• How many ATP are produced in cellular respiration?