U2T2 - Keywords Flashcards
Photosynthesis
Photosynthesis
Conversion of sunlight energy into chem energy in form of complex carbohydrates. Transduction. Occurs in chloroplasts.
Transduction
Conversion of 1 form of energy into another.
Photon
Package of light energy.
Light Harvesting
Process of absorbing light in photosystems attached to thylakoid membranes of chloroplast. Raises energy levels of electrons in chlorophyll. Most red + blue light absorbed. Primary pigment emits electron to electron acceptor.
Photosystem
2 types. Composed of hundreds of pigment molecules like chlorophyll. Contains primary pigment and accessory pigments.
Primary Pigment
In photosystem. 1 molecule that acts as reaction centre.
Accessory pigments
Molecules in photosystem which funnel light photons onto primary pigment.
Antenna Complex
All accessory pigments together. Harvests light over range of diff wavelengths. As light passes through, special proteins pass absorbed energy by resonance transfer towards reaction centre. Molecules must be part of regular arranged structure.
Photosystem 1
Contains primary pigment P700 which absorbs light wavelength of 700nm.
Photosystem 2
Contains primary pigment P680 which absorbs light wavelength of 680nm.
Photoactivation
Light energy used to excite electrons within primary pigment to higher energy level.
Chlorophyll
Combo of diff pigments (chlorophyll a + b, carotenoids)Chlorophyll has ring like structure, Mg centre joined to hydrophobic hydrocarbon tail, anchoring in thylakoid. Carotenoids include xanthophylls + carotenes (yellow/orange, red/brown) Accessory pigments, absorb light of diff wavelengths + pass energy onto chlorophyll to assist in photoactivation.
Action Spectra
Graph of rate of photosynthesis vs wavelength. Rate dependent on wavelength.
Absorption Spectra
Graph of absorption vs wavelength.
Light Independent Stage
Occurs within stroma. To fix CO2 into organic compounds. ATP + NADPH from light dependent stage required, Calvin Cycle shows intermediate molecules.