Chapter 10: Photosynthesis (no Calvin Cycle)

Organisms that photosynthesize

Photosynthetic Bacteria (cyanobacteria)

Photosynthetic Protists (Euglena)

Algae and Seaweeds

Plants

Where does photosynthesis occur (environments)?

freshwater and marine environments

terrestrial plants

Diatoms and Phytoplankton

main, general point of photosynthesis

capture light energy to drive synthesis of organic molecules

Solar energy → Chemical energy

Photosynthesis requires

CO2 + Water (H2O) + Light

Cellular Respiration produces

CO2 + Water (H2O)

Chloroplasts are mainly found in

Mesophyll cells

Mesophyll cells

the primary photosynthetic cells found within a plant leaf

Xylem and Phloem

Stroma

the fluid-filled space inside chloroplasts; light-independent reactions / Calvin Cycle occurs here

Thylakoids

a flattened, membrane-bound sac located inside chloroplasts of plant cells; light-dependent reactions occur here

Granum

stacks of thylakoid

Basic leaf structure (top → bottom)

Cuticle→Upper Epidermis→Mesophyll→Lower Epidermis→Stomata

Cuticle

waxy covering of leaves

made of Cutin

non-polar, repels water

Upper epidermis

produces cuticle

protects the leaf by aiding in preventing water loss and providing an extra layer between the outside and inside of the leaf

Xylem

transport water and dissolved minerals from the roots of a plant, through the stem, and up to the leaves

Phloem

transport sugars (carbohydrates) produced during photosynthesis from the leaves ("source tissues") to other parts of the plant

Lower epidermis

facilitate gas exchange through tiny pores called stomata, allowing carbon dioxide to enter the leaf and oxygen to exit, while also regulating water loss by opening and closing these stomata with the help of guard cells

Stomata

primary means for gas exchange via opening and closing via Guard Cells

Electromagnetic Spectrum

visible light from 380nm-740nm

small wavelength = more energy

large/long wavelength = less energy

Photons

discrete unit of light

Chlorophyll a

green pigment b/c absorbs blue and red light

absorbs light energy for photosynthesis (main)

Chlorophyll b

abosrbs light at wavelengths where Chlorophyll a is less efficient

absorbs blue and red light (but at lower wavelengths than Chlorophyll a)

Carotenoids

absorbs light where Chlorophyll a/b cannot (blue-green light)

appears red, yellow, orange

Photosynthesis equation

6CO2 + 6H2O → C6H12O6 + 6O2

Light/Hill Reaction

occurs on Thylakoid Membrane

Photosystems II/I: have Light Harvesting (Antenna pigments) and Reaction Center Complexes (Chlorophyll a)

P680 (PSII) / P700 (PSI)

Photolysis

splitting of water molecules

H2O → 2H+, 2e-, 1/2O2

H+ = gradient (thylakoid space)

e- = replacement

O2 = released

Products of the Light Reaction

O2, ATP, NADPH

Path of Light Reaction

Light→P680→Primary e- Acceptor→Pq→Cytochrome Complex→Pc→P700→Primary e- Acceptor→Fd→NADP+ Reductase→NADPH