Chapter 3: Photosynthesis Flashcards
Chlorophyll
The light-absorbing green-coloured pigment that begins the process of photosynthesis.
Porphyrin
The light-absorbing portion of the chlorophyll molecule, containing a magnesium atom surrounded by a hydrocarbon ring.
Cyanobacteria
The largest group of photosynthesizing prokaryotes.
Epidermis Layer
The transparent colourless layer of cells below the cuticle of a leaf, stem or root.
Mesophyll Layers
The photosynthetic cells that form the bulk of a plant leaf.
Guard Cells
Photosynthetic epidermal cells of a leaf or stem that form and regulate the size of an opening called a stoma.
Stomata
Openings on the surface of a leaf that allow for the exchange of gases between air spaces in the leaf interior and the atmosphere.
Transpiration
The loss of water vapour from plant tissues, primarily through stomata.
Vascular Bundles
A system of tubes and cells that transport water and minerals from the roots to the leaf cells and carry carbohydrates from the leaves to other parts of a plant, including the roots.
Stroma
The protein-rich semiliquid material in the interior of a chloroplast.
Thylakoids
A system of interconnected flattened membrane sacs forming a separate compartment within the stroma of a chloroplast.
Grana (singular: granum)
A stack of thylakoids
Lamellae (singular: lamella)
Unstacked thylakoids between grana
Thylakoid Membrane
The photosynthetic membrane within a chloroplast that contains light- gathering pigment molecules and electron transport chains.
Thylakoid Lumen
The fluid-filled space inside a thylakoid.
Light Reactions
The first set of reactions of photosynthesis in which light energy excites electrons in chlorophyll molecules, powers chemiosmotic ATP synthase, and results in the reduction of NADP+ to NADPH.
Carbon Fixation
The process of incorporating CO2 into carbohydrate molecules.
Calvin Cycle
A cyclic set of reactions occurring in the stroma of chloroplasts that fixes the carbon of CO2 into carbohydrate molecules and recycles enzymes.
Electromagnetic (EM) Radiation
A form of energy that travels at 3 X 10^8 m/s in wave packets called photons that include visible light.
Photons
Packets of EM radiation (also known as quanta)
Spectroscope
An instrument that separates different wavelengths into an electromagnetic spectrum.
Electromagnetic Spectrum
Photons separated according to wavelength.
Photosystems
Clusters of photosynthetic pigments embedded in the thylakoid membranes of chloroplasts that absorb light energy.
Action Spectrum
A graph illustrating the effectiveness with which different wavelengths of light promote photosynthesis.
Absorption Spectrum
A graph illustrating the wavelengths of light aborbed by a pigment.
β-carotene
A carotenoid pigment found in photosystems that also forms vitamin A in animals.
Xanthophylls
Pigments in chloroplast membranes that give rise to the yellow colour in autumn leaves.
Anthocyanins
Pigments in vacuoles that give rise to the red colour in autumn leaves.
Photosynthestically Active Radiation (PAR)
Wavelengths of light between 400 nm and 700 nm that support photosynthesis.
Ground State
The lowest possible potential energy level of an atom’s electron.
Fluorescene
The release of energy as light as an atom’s electron returns to its ground state.
Excitation
The absorption of energy by an atom’s electron.
Primary Electron Acceptor
A compound embedded in the thylakoid membrane that is reduced by an excited chlorophyll electron.
Antenna Complex
A web of chlorophyll molecules embedded in the thylakoid membrane that transfers energy to the reaction centre.
Reaction Centre
A transmembrane protein complex containing chloropyll a whose electrons absorb light energy and begin the process of photosynthesis.
Photosystem I
A photosystem embedded in the thylakoid membrane containing chlorophyll P700.
Photosystem II
A photosystem embedded in the thylakoid membrane containing chlorophyll P680.
Noncyclic Electron Flow
The process in which photon-energized electrons flow from water to NADP+ through electron transport chains in thylakoid membranes, producing NADPH by reduction and ATP by chemiosmosis.
Z Protein
A protein associated with photosystem II that splits water into hydrogen ions, oxygen atoms and electrons.
Phototphosphorylation
The light-dependent formation of ATP by chemiosmosis in photosynthesis.
Cyclic Electron Flow
Flow of photon-energized electrons from photosystem I, through an electron transport chain that produces ATP by chemiosmosis but no NADPH
C3 Photosynthesis
Photosyntesis in which a three-carbon intermediate is first formed when CO2 is incorporated into organic acid molecules.