Chapter 7: Photosynthesis Flashcards
Chlorophyll
A green pigment which absorbs red and blue light in order or photosynthesis to take place.
Mesophyll
The inner tissue of the leaf which contains chloroplasts.
Stomata
Any of the minute pores in the epidermis of the leaf or stem of a plant, forming a slit of variable width that allows movement of gases in and out of the intercellular spaces.
Primary acceptor
The molecule to which a high-energy electron from an excited pigment molecule is transferred.
In the thylakoid membrane of a chloroplast or in the membrane of some prokaryotes, a specialized molecule that shares the reaction-center complex with a pair of chlorophyll a molecule and that accepts an electron from them.
Accessory pigments
Blue and Red pigments drive photosynthesis.
Absorption spectrum
Measures what pigments are most highly absorbed from leaves.
Action Spectrum
Measures what pigments drive photosynthesis (very similar to absorption spectrum).
Photosystem 1 (PS1)
Re-excites electrons giving them enough energy to reduce NADP+ into NADPH.
Photosystem 2 (PS2)
Oxidizes H2O and takes its electrons. This produces O2 and 4H+ ions and supplies 4 electrons to the ETC.
Antenna Complex
Light Harvesting Systems: protein-pigment complexes in or on photosynthetic membranes. They receive radiant energy and transfer it to the exaction centres; an array of LHS is referred to as an ‘antenna’.
Reaction Centre
Captures the energy of light, They absorb light and use the energy to excite chlorophyll electrons.
RUBISCO (Ribulose-1,5-bisphosphate carboxylase oxygenase)
The most abundant enzyme on earth which fixes CO2.
What happens in the Thylakoids? (3)
- Light absorption by chlorophylls and carotenoids
- Electron Transport
- ATP synthesis by ATP synthase
What happens in the Stroma (space around the thylakoids)? (1)
The Calvin Cycle takes place here.
What is exchanged through the Stomata? (2)
Oxygen and Carbon dioxide
What are Carotenoids?
Usually red, orange, or yellow pigments, and include the familiar compound carotene, which gives carrots their colour. Carotenoids cannot transfer sunlight energy directly to the photosynthetic pathway, but must pass their absorbed energy to chlorophyll. For this reason, they are called accessory pigments.
How are the Action and Absorption Spectrum related?
The pigments which are most highly absorbed are the same as the pigments which drive photosynthesis.
Phosphorylation: How ATP is produced in light-dependant reactions
The build up of H+ ions in the thylakoid lumen
is used by an ATP synthase
to convert ADP to ATP
What is the basic function of the ETC?
It moves electrons, losing energy, while pumping H+ ions into the thylakoid lumen (generating a pmf).
What is the importance of RUBISCO to life on Earth?
The most abundant enzyme on earth and it accounts for about 40% of leaf soluble protein.
