Biology Chapter 4.2
Photosynthesis
KEY CONCEPTThe overall process of photosynthesis produces sugars that store chemical energy.
Photosynthetic organisms are producers.• Producers make their own
source of chemical energy.• Plants use photosynthesis and
are producers.• Photosynthesis captures energy
from sunlight to make sugars.
• Chlorophyll is a molecule that absorbs light energy.
chloroplast
leaf cell
leaf
• In plants, chlorophyll is found in organelles called chloroplasts.
Photosynthesis in plants occurs in chloroplasts.
• Photosynthesis takes place in two parts of chloroplasts.– grana (thylakoids)– stroma
chloroplast
stroma
grana (thylakoids)
• The light-dependent reactions capture energy from sunlight.– take place in thylakoids– water and sunlight are needed– chlorophyll absorbs energy– energy is transferred along thylakoid membrane then to light-independent
reactions– oxygen is released
• The light-independent reactions make sugars.– take place in stroma– needs carbon dioxide from atmosphere– use energy to build a sugar in a cycle of chemical reactions
• 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
chloroplast1
2
43
energy
stroma (fluid outside the thylakoids)
Photosynthesis (19 min)
• http://player.discoveryeducation.com/index.cfm?guidAssetId=6156A4EE-3DBC-4C44-9677-1413C6AC85C5&blnFromSearch=1&productcode=US
Dark Reactions of Photosynthesis
• http://player.discoveryeducation.com/index.cfm?guidAssetId=750578E5-E9F6-40A2-90EA-E97F5D0CBE80&blnFromSearch=1&productcode=US
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