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.
RuBP
Ribulose 1,5 Bisphosphate. CO2 acceptor.
RUBISCO
Ribulose Bisphosphate Carboxylase Oxygenase. Most abundant enzyme on earth. Catalyses CO2 + RuBP.
GP
Glycerate 3 phosphate. GP/PG/Phosphoglyceric acid.
Compensation Point
When light intensity is such that photosynthesis and respiration are at equal rate and CO2 absorbed vs released is the same (or O2)
Gross Photosynthesis
Total amount of photosynthesis occurring. Measured by amount of O2 or carb produced. Some products used by plant in resp, leading to net.
Net Photosynthesis
Gross photosynthesis - resp demands of plant.
Total photosynthesis minus products used in resp.
At compensation point, this is 0.
Chloroplast
Large organelle with thylakoids containing chlorophyll to absorb light.
Thylakoids
Flattened membranes in chloroplast. Contain systems of electron carriers + associated enzymes. Arranged in stacks called grana. Linked by intergranal lamellae.
Non-cyclic photophosphorylation
Production of ATP in photosynthesis.
Palisade layer
A layer of parallel elongated cells below the epidermis of a leaf which contain lots of chloroplasts and chlorophyll for photosynthesis.
Chlorophyll
A green pigment which is responsible for the absorption of light to provide energy for photosynthesis.
Electron carrier
Any of various molecules that are capable of accepting one or two electrons from one molecule and donating them to another in the process of electron transport. As the electrons are transferred from one carrier to another, their energy level decreases, and energy is released.
Limiting factor
Variable of a system that, if subject to a small change, causes a non-negligible change in an output or other measure of the system.
Light dependent stage
The series of biochemical reactions in photosynthesis that require light energy that is captured by light-absorbing pigments (such as chlorophyll) to be converted into chemical energy in the form of ATP and NADPH. Occurs in thylakoid membranes in chloroplast. Water is dissociated and it’s H2 ions reduce NADP.
Reaction centre
A complex of several proteins, pigments and other co-factors that together execute the primary energy conversion reactions of photosynthesis.
Resonance transfer
Transfer of energy from one fluorochrome to another. The emission wavelength of the fluorochrome excited by the incident light must approximately match the excitation wavelength of the second fluorochrome. Energy is funnelled to the reaction centre of a photosystem using this method.
Photophosphorylation
The synthesis of ATP from ADP and phosphate that occurs in a plant using radiant energy absorbed during photosynthesis.
Photolysis
The decomposition or separation of molecules by the action of light.
NADP
Nicotinamide adenine dinucleotide phosphate. A coenzyme that occurs in many living cells and functions as an electron acceptor like NAD but reacts with different metabolites. Has an extra phosphate group.
Photoactivation
The process of activating a substance by means of radiant energy and especially light.
Stroma
The matrix of a chloroplast, in which the grana are embedded.
