Chapter 5 Photosynthesis

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Chapter 5 - Photosynthesis

• High School Biology Class

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Chapter 5 - Overview
1. SUN
2. LIGHT ENERGY
3. PHOTOSYNTHESIS
5. RESPIRATION
6. ATP (CELL ENERGY)
4. CHEMICAL ENERGY
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Energy Formation in Cells
Organic Compounds Oxygen

ATP
Energy for Life
Carbon Dioxide Water
ADP and P
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What is Photosynthesis?

• The process of photosynthesis is where organisms
  convert light energy into chemical energy to
  create products such as carbohydrates, sugars,
  and starches.

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Where does it occur?

• In plants that are able to capture sunlight to
  make their own food (aka autotrophs.)
• The actual process occurs inside a cells
  chloroplasts.

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What does it need?

• CARBON DIOXIDE (CO2)
• WATER  (H20)
• SUNLIGHT

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What happens? (photosynthesis equation)
Water
Carbohydrates
6CO2
6H2O
ENERGY
C6H12O6
6O2
Sunlight
Carbon Dioxide
Oxygen
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How does happen?

• The process of photosynthesis does not happen all
  at once. It is a very long process that is broken
  into 3 stages.

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Stage 1 Light Reactions

• Light is absorbed from the sun by the
  chloroplasts.
• H2O is taken into the cell as well.
• The light energy is used to split H20 into 3
  separate parts (H, O2, and electrons.)

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How does it work?

• Inside the chloroplasts are disk-shaped
  structures called thylakoids that contain
  different pigments.

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How does it work?

• Pigments do the actual absorbing of light.
• a) Chlorophylls absorb red and blue light
• (produce green colors)
• b) Carotenoids absorb other colors
• (produce yellow and orange colors)

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How does it work?

• Once the sunlight is captured it is used to split
  water (H20) into Hydrogen (H), Oxygen gas (O2),
  and free electrons.
• Oxygen gas (O2) is free to leave the plant and
  this is what animals use to breathe.

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Stage 2 Energy Storage

• Free electrons are passed from thylakoid to
  thylakoid until they reach an ADP molecule and
  turn it into an ATP.
• Hydrogen (H) molecules are passed from protein to
  protein until they reach a NADP molecule and
  then they become an NADPH.

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How does it work?

• As electrons continuously get passed on this
  process is known as the electron transport chain.
  

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Stage 3 Dark Reactions

• The newly formed ATP and NADPH power the
  formation of carbohydrates, sugars, and starches.
• This is done by using CO2 as the starting
  material.

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How does it work?

• Carbon Dioxide (CO2) enters the cell from the
  atmosphere and undergoes a process called the
  Calvin Cycle which creates simple sugars.

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Step 1

• A Carbon Dioxide molecule is joined to a 5-carbon
  compound called RuBP (ribulose bisphosphate) to
  create a 6-carbon compound. 

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Step 2

• The newly formed 6-carbon compound immediately
  splits into two 3-carbon compounds.

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Step 3

• One of the new 3-carbon compounds is used to make
  the initial 5-carbon compound that originally
  joined to the Carbon Dioxide.

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Step 4

• The second 3-carbon compound is used to make
  carbohydrates, sugars, and starches.

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Summary of Stages
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Factors that affect it?

• Light intensity
• Amount of CO2 available
• Temperature
• If any of these factors increase the
  photosynthesis process also increases and vice
  versa.

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Photosynthesis

H2O
CO2
Energy
ATP and NADPH2
Which splits water
Light is Adsorbed By Chlorophyll
Calvin Cycle
ADP NADP
Chloroplast
Used Energy and is recycled.
O2
C6H12O6

Light Reaction
Dark Reaction
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• Photosynthesis
• Capturing Energy from the Sun
• Using energy to make ATP and NADPH
• Using ATP and NADPH to make carbohydrates,
  sugars, and starches

Light Dependent Reactions Light Independent
Reactions (Calvin Cycle)
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Any Questions?

• Education is light, lack of it darkness.
• --Russian Proverb
• Education is the movement from darkness to
  light. --Bloom