• Photosynthesis is the process that converts solar energy into chemical energy • Autotrophs are the producers (producing organic molecules from CO

(1)

• Photosynthesis is the process that converts solar energy into chemical energy

• Autotrophs are the producers (producing organic molecules from CO₂ and other inorganic molecules)

• plants, algae, certain other protists, and some prokaryotes

• photoautotrophs

(2)

• Heterotrophs (the consumers) obtain their organic material from other organisms

• The oxidation of H2O produces molecular oxygen (O2) as a byproduct; because of this, the photosynthetic process in

(3)

• Carl Woese realized in the 1970s that the

sequence of rRNA molecules and their genes could be used to infer evolutionary relationships between organisms.

(4)

Chloroplasts: The Sites of Photosynthesis in Plants

• Leaves, chlorophyll, stomata, mesophyll

• The chlorophyll is in the membranes of

thylakoids; thylakoids may be stacked in columns called grana

• Chloroplasts also contain stroma, a dense fluid

• Photosynthesis is a redox process in which H₂O is oxidized and CO₂ is reduced

• ^{6 CO}²^{+ 12 H}²O + Light energy  C₆H₁₂O₆ + 6 O₂ + 6 H₂O

(5)

• Photosynthesis consists of the light reactions (the photo part) and Calvin cycle (the synthesis part)

• Generating ATP from ADP by photophosphorylation

(6)

• Chlorophyll a is the main photosynthetic pigment

• Accessory pigments, such as chlorophyll b,

• Accessory pigments called carotenoids

• When a pigment absorbs light, it goes from a ground state to an excited state, which is

unstable

(7)

• A photosystem

• reaction-center complex (primary electron acceptor is here)

• light-harvesting complexes

(8)

• two types of photosystems

• Photosystem II (PS II) absorbing a wavelength of 680 nm

• Photosystem I (PS I) is best at absorbing a wavelength of 700 nm

• cyclic and linear electron flow