Photosynthesis
Recall:
6CO2
+
12H2O
+
Energy → C6H12O6 +
(Light)
6O2 +
6H2O
 Photosynthesis is believed to have originated in
bacteria
 Overall equation is exactly the opposite of the
equation for aerobic cellular respiration
 This does not mean that the process is exactly the
opposite to cellular respiration
 Photosynthesis requires structures and metabolic
processes similar to those used in the
mitochondria: electron transport chains, dissolved
enzymes, and a membrane-enclosed space for
chemiosmosis
Photosynthesis consists of two classes of reactions:
1. Light Dependent Reactions (Light Reactions)
- converts solar energy into chemical energy (requires light)
- produce ATP and NADPH to be used in the light independent
reactions (Dark Reactions)
- NADP+ is the electron carrier in photosynthesis
(NADPH is the reduced form)
NADP+ +
(2e + H+)
NADP+ +
2e →
→
NADP-
NADPH
+
H+ →
NADPH
- occurs in the thylakoid membrane of the chloroplast
2. Light Independent Reactions (Dark Reactions)
- series of reactions that synthesize PGAL which is used to
produce glucose
- occur in the stroma of the chloroplast