Photosynthesis Intro and Chloroplast Structure (+ Chomatography)

Photosynthesis - big picture

Transforms light energy into chemical energy: glucose + organic molecules

Photosynthesis Equation

6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O

Photosynthetic Organisms

Autotrophs - can produce their own chemical energy. Called producers.

• Photoautotrophs - use light to produce chemical energy

• Examples: plants, algae, cyanobacteria

Location of Photosynthesis in Plants

In leaves, mesophyll cells - Palisade & spongy

in chloroplasts

Chloroplast Structure

Double membrane

• Outer membrane

• Inner membrane

Thylakoids: flattened membrane-bound sacs (high SA:V ratio)

• Thylakoid membrane surrounds it. Contains chlorophyll embedded, also location of light reaction

• Thylakoid Space/Lumen - inner region of thylakoid

• arranged in stacks called grana/granum

Stroma: fluid filled space between inner membrane and the thylakoid membrane. Contains enzymes and and calvin cycle material (location of Calvin cycle).

Three Distinct Spaces

Intermembrane Space - between inner and outer membrane

Stroma - inner mebrane and thylakoid membrane

Thylakoid Space, aka Lumen - w/in the thylakoid mebrane, lamellae connect yo make space continuous

IB Skill: Chloroplast Structure

Outer membrane - only these need two lines

Inner membrane - only these need two lines

Stroma

Thylakoid

Thylakoid Space/Lumen

Thylakoid Membrane

Granum

Lamellae - flattened membrane sacs

(know functions)

EM Spectrum

400nm - purple/blue

750nm - red

Photosynthetic Pigments

Pigments: molecules that absorb light

• Wavelengths not absorbed are reflected; this is the color we perceive

• Most common: chlorophyll (a)

• Accessory: xanthophyll (yellow) and carotenoids (orange)

  • Function: expand range of light absorption that chlorophyll misses

Chlorophyll

Main pigment. Chlorophyll a and b reflect green light

Absorption Spectrum

Each line represents ONE TYPE of pigment.

→ More light absorption = faster photosynthesis

Action Spectrum

Graphical representation shows effectiveness of wavelength of light on photosynthesis. Takes into account ALL pigments in chloroplasts, this is the overall rate of photosynthesis

→ Most photosynthesis in higher regions

Paper Chromatography

Used to see what pigments are in a substance

Solubility and Pigments

More soluble - farther distance traveled

Retention Factor (R_f)

R_f = sample distance / solvent distance

NO UNITS

To TWO decimal places