Topic 5 - energy transfers in and between organisms
location of the light dependent reaction
thylakoid membranes of chloroplast
location of the light independent reaction
stroma of chloroplast
thylakoid membranes
Folded membranes containing photosynthetic proteins (chlorophyll). Embedded with transmembrane electron carrier proteins. Involved in the LDRs.
chlorophyll
Located in proteins on thylakoid membranes. Mix of coloured proteins that absorb light. Different proportions of each pigment lead to different colours on leaves.
advantage of many pigments
Each pigment absorbs a different wavelength of visible light. Many pigments maximises spectrum of visible light absorbed. Maximum light energy taken in so more photoionisation and higher rate of photosynthesis.
Light-dependent reaction
First stage of photosynthesis. Occurs in thylakoid membranes. Uses light energy and water to create ATP and reduced NADP for LIR. Involes photoionisation of chlorophyll, photolysis and chemiosmosis.
Photolysis
Light energy absorbed by chlorophyll splits water into oxygen, H+ and e-. H20 ---> 1/2 02 + 2e- + 2H+
products of photolysis
H+ : picked up by NADP to form reduced NADP for LIR
e- : passed along chain of electron carrier proteins
oxygen : used in respiration or diffuses out leaf via stomata