Chapter 8 Photosynthesis

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Chapter 8 Photosynthesis

• CP Biology A

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8-1 Energy and Life

• Plants and some other types of organisms are able
  to use light energy from the sun to produce food.
• - Remember autotrophs and heterotrophs

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• Energy the ability to do work
• Organisms store energy in the chemical bonds of
  molecules
• ATP (adenosine triphosphate) is used by all types
  of cells as their basic energy source.
• - Adenine
• Ribose 5 carbon sugar
• Three phosphates

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ATP Structure
Adenine
Ribose
3 Phosphate groups
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ATP to ADP

• Energy stored in ATP is used for many things
• Active transport in cell membrane
• Synthesis of proteins, lipids, nucleic acids
• Breakdown of carbs, lipids
• Energy is released by breaking the bond between
  the second and third phosphates
• Once the bond is broken, the molecule ADP is left
  over adenosine diphosphate

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ATP vs ADPcomparison to batteries
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8-2 Photosynthesis An Overview

• Photosynthesis is a series of reactions that uses
  the energy of sunlight to convert water and
  carbon dioxide into high-energy sugars and
  oxygen.
• Chemical equation 6CO2 6H2O energy ?
  C6H12O6 6O2
• Word equation carbon dioxide water light ?
  glucose oxygen

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Light and Pigments

• Photosynthesis requires light and chlorophyll, a
  molecule in chloroplasts
• Visible spectrum the wavelengths of light that
  we can see as different colors ROY G BIV

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• Pigment light-absorbing molecules
• Chlorophyll plants main pigment
• Two main types Chlorophyl a and Chlorophyl b
• Collects blue-violet and red light
• Reflects green light, so appears green to us

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Chlorophyll Light Absorption
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8-3 The Reactions of Photosynthesis

• Photosynthesis is split into 2 parts
• Light-dependent reactions ? occurs in thylakoid
• Light-Independent reactions ? Calvin Cycle ?
  occurs in stroma

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Photosynthesis Overview
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Electron Carriers

• Sunlight excites electrons giving them energy,
  but these high-energy electrons need to be
  carried by special molecules
• Electron carriers are molecules that accept a
  pair of high-energy electrons and move them.
• NADP (nicotinamide adenine dinucleotide
  phosphate) 2 e- 2 H ? NADPH

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• Light Dependent Reactions produce oxygen gas and
  convert ADP and NADP into the energy carriers
  ATP and NADPH.

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• Calvin Cycle uses ATP and NADPH to produce
  high-energy sugars.
• 6 Molecules of carbon dioxide ? to produce a 6
  carbon sugar

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Factors Affecting Photosynthesis

• Changing the rate of photosynthesis
• A shortage of water will slow the rate
• Temperature can affect enzymes that work in
  photosynthesis
• The amount of light can also increase or decrease
  the rate