Photosynthesis
• Carried out by autotrophs, this is the principal means by which energy enters the food chain.
Photosynthesis
• The chemical equation for photosynthesis is below.
• Photosynthesis uses the energy from sunlight to convert water and carbon dioxide into sugar
and oxygen.
• Chloroplasts are the organelles in which photosynthesis takes place.
• Within the chloroplasts are chlorophyll A and chlorophyll B, pigment molecules that help
absorb light.
When Chlorophylls Absorb Light
Sunlight → Chlorophyll
• The absorption of light energy by a chlorophyll causes an electron to gain energy, or “jump.”
• Normally, an electron releases this extra energy and returns back to its “ground state.”
• But in organisms, special molecules known as electron acceptors can capture the extra
energy and carry it to other molecules for use.
,
• NADP+ is one such electron acceptor that can capture a pair of high-energy electrons
(converting it to NADPH) and shuttle them elsewhere for use.
• Both chlorophyll A and chlorophyll B have specific wavelengths in which they can absorb
light.
Inside a Chloroplast
• Thylakoids are saclike photosynthetic membranes.
• Proteins in the thylakoid membrane organize chlorophyll and other pigments into
photosystems.
• Photosystems refer to the light-collecting “unit” of a chloroplast.
• The stroma is the space outside the thylakoid membrane.
• Carried out by autotrophs, this is the principal means by which energy enters the food chain.
Photosynthesis
• The chemical equation for photosynthesis is below.
• Photosynthesis uses the energy from sunlight to convert water and carbon dioxide into sugar
and oxygen.
• Chloroplasts are the organelles in which photosynthesis takes place.
• Within the chloroplasts are chlorophyll A and chlorophyll B, pigment molecules that help
absorb light.
When Chlorophylls Absorb Light
Sunlight → Chlorophyll
• The absorption of light energy by a chlorophyll causes an electron to gain energy, or “jump.”
• Normally, an electron releases this extra energy and returns back to its “ground state.”
• But in organisms, special molecules known as electron acceptors can capture the extra
energy and carry it to other molecules for use.
,
• NADP+ is one such electron acceptor that can capture a pair of high-energy electrons
(converting it to NADPH) and shuttle them elsewhere for use.
• Both chlorophyll A and chlorophyll B have specific wavelengths in which they can absorb
light.
Inside a Chloroplast
• Thylakoids are saclike photosynthetic membranes.
• Proteins in the thylakoid membrane organize chlorophyll and other pigments into
photosystems.
• Photosystems refer to the light-collecting “unit” of a chloroplast.
• The stroma is the space outside the thylakoid membrane.
