UNIT 5: Photosynthesis and Respiration

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UNIT 5 Photosynthesis and Respiration

• BIG IDEA Energy is produced and released by
  making and breaking chemical bonds

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Think About It

• With your partner, come up with a list of
  activities that you do that requires energy
• What gives us energy?

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Energy

• Directly or indirectly , all energy in living
  things comes from the sun

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Obtaining Energy

• Autotrophs
• Organisms that are capable of making food
  (energy) from simple inorganic substances
• EX green plants, algae

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Two Types of Autotrophs

• 1. Photoautotrophs use carbon dioxide and light
  energy to drive reactions needed to make food

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Next type

• 2. Chemoautotrophs utilize inorganic chemicals
  for the energy to drive food making reactions

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Obtaining Energy

• Heterotrophs
• Organisms that cannot make their own food
  (energy) and must depend on other plants or
  animals as food source (energy)
• Examples Humans, dogs, cats

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Photosynthesis

• Process of capturing energy of sunlight and
  transforming it into chemical energy
• CO2 H2O----glucose O2

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Photosynthesis

• Two stages
• Light reactions- light energy is converted into
  chemical energy of two intermediate molecules
• Calvin cycle-Organic molecules are formed from
  CO2

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Photosynthesis

• Sunlight, sometimes called white light, is a form
  of energy that travels in waves
• Wavelength the distance between the crest of one
  wave and the crest of the next wave

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Visible Light Spectrum

• Depends on wavelength
• Blue 380 (nm)
• Green 500 (nm)
• Yellow 560 (nm)
• Light red 600 (nm)
• Darker red 750 (nm)

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Photosynthesis

• Pigments absorb light
• EX a red object absorbs all the visible colors
  of the spectrum except red which is reflected and
  gives the object the red color

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Types of Photosynthetic Pigments

• Chlorophylls absorb red and blue light, appear
  green
• Carotenes absorb blue, appear orange
• Xanthophylls appear yellow, may not be used to
  absorb light

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                  The color of an egg yolk
is from the xanthophyll carotenoids lutein and
zeaxanthin

• The color of an egg yolk is from the xanthophyll
  carotenoids lutein and zeaxanthin

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CHLOROPLAST

• Site of Photosynthesis

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PARTS OF THE CHLOROPLAST
Inner and outer membrane Thylakoids Grana Strom
a
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Parts of the Chloroplast

• Thylakoid- Membrane of the thylakoid contains
  photosynthetic pigments flattened sacs
• Site of the light reactions

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Parts of the Chloroplast

• Grana- Stacks of thylakoids
• Stroma-Region b/t grana
• Site of the light independent reactions

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Photosynthesis Reactions

• Light Dependent Reactions-energy from light makes
  the reaction happen
• Light Independent Reactions- Doesnt need the
  energy from light to make the reaction happen but
  they do need products of the light reaction to
  proceed.

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Steps in Light Dependent
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Light Dependent Reactions- In the Chloroplast

• Pigments in the photosynthetic membranes absorb
  light (pigments are located in Photosystem I II
• When the light hits the chlorophyll in
  Photosystem II the electrons become excited and
  jump up.

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• The electrons are captured by the electron
  transport chain.
• We need to replace the electrons that are lost so
  we steal some from water . This breaks the water
  molecule apart forming H and O

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• As we transport electrons down the chain we use
  their energy to produce ATP
• The electrons now go to Photosystem I and it
  loses electrons to NADP to make it NADPH.

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The final products of the light reaction

• At the end of the light reaction we have made
• NADPH
• ATP
• O2

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Reactants used during the light reaction

• Water
• Also used sunlight

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Light independent reaction ( Calvin Cycle)

• A. Use CO2 , ATP, NADPH
• B. Uses products from light reaction (Light is
  not necessary for this reaction)
• C. Location stroma

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Steps in Light Independent Reaction

• 6 CO2 reacts with the sugar, ribulose phophate
  (RuBP)?sugar called phosphoglycerate (PGA)
• PGA?12 phosphoglyceraldehyde (PGAL)
• NADPH and ATP from light reaction provide energy
  for this step

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Steps in Light Independent Reaction (cont)

• PGAL does 2 things
• Makes more RuBP to continue cycle (requires 10
  PGAL to do this)
• b. Form 1 glucose (requires 2 PGAL)

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Concept Map
Section 8-3
Photosynthesis
includes
takes place in
uses
use
take place in
to produce
to produce
of
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Figure 8-7 Photosynthesis An Overview
Section 8-3
Chloroplast
Chloroplast
NADP
ADP P
Calvin Cycle
Light- Dependent Reactions
ATP
NADPH
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Factors Affecting Photosynthesis

• Four main types
• Light intensity
• Temperature
• Water
• Mineral availability

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Cellular Respiration

• Release of the energy stored in food
• Occurs in the inside of the cells of both
  autotrophs and heterotrophs

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Adenosine Triphosphate (ATP)

• Energy released during cellular respiration is
  stored as ATP
• Consists of adenine, ribose and three
  phosphates

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How is energy stored in ATP?

• Energy is stored in the bonds. Once a bond
  breaks (causing ATP to lose a phosphate group),
  there is a release of energy.

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Release of Energy
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Adenosine diphosphate or (ADP)

• Two phosphate groups, adenine, and ribose
• Where would the energy be in ADP

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Two Types of Cellular Respiration

• Aerobic Respiration
• Occurs in presence of oxygen
• Occurs in the mitochondria
• Produces about 36 ATP

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Second Type of Cellular Respiration

• Anaerobic Respiration
• Occurs without oxygen
• Occurs in the cytoplasm
• Produces 2 ATP

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Which type of cellular respiration is more
efficient?

• Aerobic because it produces more ATP (more energy)

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Two types of Anaerobic Respiration

• 1. Alcoholic Fermentation yeast produces alcohol
• 2. Lactic Acid Fermentation muscles produces
  lactic acid when they dont have enough oxygen

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What is the equation for cellular respiration?

• GLUCOSE 6O2?6 CO2 6 H2O Energy (36 ATP)

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What is the relationship between photosynthesis
and cellular respiration?

• Opposite reactions
• Lets write the two reactions to see