Photosynthesis

Photosynthesis chemical reaction

6 CO₂ + 6 H₂O + light energy → C₆H₁₂O₆ + 6 O₂ (light energy → chemical energy)

Roots

take water from soil

Xylem

specialized for water transport (moves H₂O from roots throughout plant), unidirectional

Phloem

specialized for sugar transport (moves sugars from green leaves to rest of plant), bidirectional

Stomates

little pores in leaves that let out CO₂

Chlorophyll

green pigment in leaves, absorbs light (blue and red, but not green or yellow)

Why are leaves green?

chlorophyll in leaves absorb blue and red pigment but let green light bounce off or reflect from leaf surface

Role of soil

gives plants something useful to stand in, holds water for plants, is full of minerals needed for metabolism to run smoothly

Components of fertilizer

nitrogen, phosphorus, potassium, calcium, magnesium, and iron

Nitrogen and phosphorus

needed to make macromolecules / proteins are build from stores carbs (C, H, and O) + large amounts of nitrogen

Radiation from sun

electromagnetic (EM) radiation

Visible light

makes up tiny part of EM radiation

Other forms of radiation from sun

x-rays, ultraviolet (UV) radiation (causes skin cancer), and microwaves

Wavelength

distance from one peak to another (for plants: captured from 400-700 nm)

Blue light

400 nm

Red light

700 nm

Photosynthesis steps

light reactions and calvin cycle

Thylakoids

membrane bound compartments inside of the chloroplasts / contains ETC for photosynthesis / light dependent reactions / contain chlorophyll

Grana

stacks of thylakoids

Light reactions

plants capture light energy from the sun / energy is transformed into chemical energy in form of ATP / plants take electrons from H₂O and transfer them to an electron carrier (NADPH)

NADPH

nicatinamide adenine dinucleotide phosphate (similar to NADH)

Calvin cycle (dark reactions)

plants capture CO₂ and convert it to sugar / conversion requires molecules made during light reactions (ATP and NADPH)

Role of electrons and NADPH

hydrogen is provided by NADPH to CO₂ to create C₆H₁₂O₆

Light reaction: step 1

pigments absorb light hooked up to ETC / ETC transfers light energy to chemical energy stored in the bonds of ATP

Light reaction: step 2

light energy used from transport of electrons pumps protons across membrane

Light reaction: step 3

ATP synthase uses potential energy of protons to make ATP

Types of photophosphorylation

noncyclic and cyclic

Noncyclic photophosphorylation (z-scheme)

electrons from chlorophyll travel through an ETC (one way ride from H₂O to NADPH) / electrons reduce NADP⁺ to NADPH

Cyclic photophosphorylation

electrons from chlorophyll travel a circuit (cycle) / electrons leave chlorophyll (when excited) to the ETC and return to chlorophyll (after energy has been transferred to ATP)

Calvin cycle: step 1

carbon fixation: enzyme (rubisco) attaches CO₂ molecules to a 5-carbon sugar called ribulose biphosphate (RuBP)

Calvin cycle: step 2

3-phosphoglycerate is phosphorylated and reduced to glyceraldehyde-3-phosphate (G3P)

Calvin cycle: step 3

some G3P used to regenerate RuBP