photosynthesis an overview 1. objectives swbat describe the process of photosynthesis swbat relate...
TRANSCRIPT
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Photosynthesis
An overview
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Objectives
• SWBAT describe the process of photosynthesis
• SWBAT relate producers to photosynthesis
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Review Vocabulary
• Chemical reaction• Carbohydrate• Enzyme• Chloroplast – where photosynthesis takes
place.
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Vocabulary
• Photosynthesis• Producers • Chlorophyll• Thylakoid • Light-dependent reactions • Light-independent reactions
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Photosynthesis – the engine of life
• Photosynthesis is carried out by producers.– You learned about producers during our ecology
unit. Make sure you know what a producer is!– Plants, some bacteria, and some protists (like the
euglena), are able to make their own energy through photosynthesis.
– They are at the base of our energy pyramid.
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Photosynthesis – the engine of life
In an energy pyramid, the producers are the base on which all other life depends (directly and
indirectly almost all energy in ecosystems begins as sunlight). Producers are the photosynthesizers.
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Photosynthesis – the engine of life• Photosynthetic organisms are producers.
• Photosynthesis is a process that captures energy from sunlight to make simple sugars (glucose).
• There are two parts to photosynthesis: the production of ATP from ADP and then the utilization of the ATP to make glucose.
Glucose is a monomer used by the plant to make other, more complex, molecules such as cellulose, starch,
and carbohydrates.
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Chlorophyll• Chlorophyll is a molecule found in chloroplasts (the
organelle that makes ATP in plants and other photosynthesizers).– Chlorophyll absorbs visible light, which the chloroplasts are
able to turn into energy.
The chlorophyll is found in the granum
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Why are plants green?
• Plants have two main types of chlorophyll.– Chlorophyll a and – Chlorophyll b
• Together chlorophyll a and b absorb mostly red and blue wavelengths of visible light.– Plants are green because neither of them absorb
green light (it is reflected and thus we see leaves as green).
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Chloroplasts
• Chloroplasts are the membrane-bound organelle where photosynthesis takes place in plants.– Most chloroplasts are in the leaf cells, which are
specialized for photosynthesis. • Two main parts to chloroplasts:
– The grana– The stroma.
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Grana
• Grana are stacks of coin-shaped membranes enclosed in compartments called thylakoids.
• The membranes of the thylakoids contain chlorophyll.
• The grana are where light-dependent (needing sunlight) reactions take place.
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Stroma
• The stroma is fluid outside the thylakoids (it surrounds the grana inside the chloroplasts).
Stroma is where the light-independent (not
requiring light) reactions take place.
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Light-dependent reactions
– take place in thylakoids– water and sunlight are
needed– chlorophyll absorbs
energy from sunlight. – energy in the form of
ATP is made in the thylakoid membrane then transferred to light-independent reactions
– oxygen is released
• The light-dependent reactions capture energy from sunlight.
The product of the light-dependent reactions is ATP synthesized from ADP – this is called photophosphorylation.
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Light-Dependent Reactions
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The light-independent reactions make glucose (known as the Calvin Cycle) .
• take place in stroma• needs carbon dioxide from atmosphere• use energy to create glucose in a cycle of chemical
reactions
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Light Independent Reactions
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Photosynthesis• The equation for the overall process is:
6CO2 + 6H2O C6H12O6 + 6O2
C6H12O6
granum (stack of thylakoids)
thylakoid
sunlight
1 six-carbon sugar
6H2O
6CO2
6O2
chloroplastchloroplast1
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energy
stroma (fluid outside the thylakoids)
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Photosynthesis