Post on 05-Jan-2016
Review Cellular Respiration
• http://www.youtube.com/watch?v=2IGIyA57Brc&feature=related
- Cellular respiration and emphasis on the electron transport chain
Photosynthesis
Why do we need to know this?
Photosynthesis
Why do we need to know this?
Renewable energy sources
Global Warming
Where our food comes from…..
YOU need to make lifestyle CHOICESand VOTE in a democracy that is
facing these DIFFICULT ISSUES
Biology and Society: Plant Power for Power Plants
– On a global scale the productivity of photosynthesis is astounding.
– All of the food consumed by humans can be traced back to photosynthetic plants.
Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
– An “energy plantation”• Is a renewable energy source.
The Basics of Photosynthesis– Almost all plants are photosynthetic
autotrophs, as are some bacteria and protists.• They generate their own organic matter through
photosynthesis.
Chloroplasts: Sites of Photosynthesis
– Chloroplasts• Are found in the interior cells of leaves.• Contain stroma, a thick fluid.• Contain thylakoids, membranous sacs.
The Overall Equation for Photosynthesis
– The reactants and products of the reaction
– In photosynthesis,
• Energized electrons are added to carbon dioxide to make sugar.
• Sunlight provides the energy.
A Photosynthesis Road Map
– Photosynthesis is composed of two processes:
•The light reactions convert solar energy to chemical energy.
•The Calvin cycle makes sugar from carbon dioxide.
The Light Reactions: Converting Solar Energy to Chemical Energy
– Chloroplasts are chemical factories powered by the sun
• That convert solar energy into chemical energy.
Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
The Nature of Sunlight– Sunlight is a type of energy called radiation
• Or electromagnetic energy.
– The full range of radiation is called the electro-magnetic spectrum.
Figure 7.5
The Process of Science: What Colors of Light Drive
Photosynthesis?– In 1883, German biologist Theodor
Engelmann• Performed an experiment using bacteria and algae
and determined that certain types of light drive photosynthesis.
Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
Figure 7.6
– Chloroplasts absorb select wavelengths of light that drive photosynthesis.
Light and Pigments
http://www.youtube.com/watch?v=IJCVg9M-7S0
Figure 7.7
Chloroplast Pigments– Chloroplasts contain several pigments:
• Chlorophyll a • Chlorophyll b • Carotenoids
How Photosystems Harvest Light Energy
– Light behaves as photons, discrete packets of energy.
– Chlorophyll molecules absorb photons.• Electrons in the pigment gain energy.
Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com)
Figure 7.9
Check out: http://science.howstuffworks.com/light-stick.htm
– A photosystem• Is an organized group of chlorophyll and other
molecules.• Is a light-gathering antenna.
How the Light Reactions Generate ATP and NADPH
– Two types of photosystems cooperate in the light reactions.
– An electron transport chain• Connects the two photosystems.• Releases energy that the chloroplast uses to
make ATP.
– The light reactions in the thylakoid membrane
Light Reactions
http://www.youtube.com/watch?v=v590JJV96lc&feature=related
The Calvin Cycle: Making Sugar from Carbon Dioxide
– The Calvin cycle• Functions like a sugar factory within a
chloroplast.• Regenerates the starting material with each
turn.
Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
Calvin Cycle
http://www.youtube.com/watch?v=mHU27qYJNU0
Figure 7.14
Water-Saving Adaptations of C4 and CAM Plants
– C3 plants
• Use CO2 directly from the air.
– Thus, C3 plants depend on the constant opening of their stomata to produce sugar.
• Are very common and widely distributed.
• Examples: rice, wheat, soybeans
– C4 plants (corn, sugarcane)• Close their stomata to save water during hot and dry
weather.• Can still carry out photosynthesis.
– CAM plants (pineapple, cactus)• Open their stomata only at night to conserve water.
A review of photosynthesis
The Environmental Impact of Photosynthesis
– Photosynthesis has an enormous impact on the atmosphere.
• It swaps O2 for CO2.
• It moderates global warming
How Photosynthesis Moderates Global Warming– Greenhouses used to grow plant indoors
• Trap sunlight that warms the air inside.
– A similar process, the greenhouse effect,• Warms the atmosphere.
• Is caused by atmospheric CO2.
– Greenhouse gases are the most likely cause of global warming, a slow but steady rise in the Earth’s surface temperature.
• Destruction of forests may be increasing this effect.
Evolution Connection:The Oxygen Revolution
– The atmospheric oxygen we breathe is a by-product of photosynthesis.
Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
– Cyanobacteria were the first organisms to carry out photosynthesis.
– The production of oxygen changed the Earth forever.
• The “oxygen revolution” was a major episode in the history of life on Earth.