Zusammenfassung der Ressource
Chloroplasts
- Structure
- inner membrane contains transport proteins
- allows an exchange of substances
between cytoplasm and stroma
- link
- stacked thylakoid membranes increase surface
area for photosynthetic pigments, electron carriers
and ATP synthase enzymes
- assists light dependant
stage of photosynthesis
- photosynthetic pigments
arranged into photosystems
- allows maximum absorption of light energy
- grana are sorrounded
by the stroma
- products of light dependant can pass
into stroma for light independant
- link
- stroma contains enzymes to catalyse
reactions of light independant
- increases rate of light independant
- proteins embedded
in grana
- hold photosystem
in place
- chloroplasts contain basic
ribosomes and DNA
- can make some of the protein
needed for photosynthesis
- Photosynthetic
pigments
- absorbs certain wavelengths of
light and reflects others
- appears as colour that it reflects
- many different
pigments act together
- to capture as much
light energy as possible
- they're found in
thylakoid membranes
- arranged in photosystems
(funnel shape)
- Chlorophyll
- a mixture of pigments of similar
structure
- one long phytol (hydrocarbon) chain and porphryn
group (similar to haem group but with magnesium atom)
- when the right wavelengh of light
hits it, two electrons become excited
- chlorophll A is yellow-green and can
either be P680 or P700
- each absorbs red light at a slightly
different wavelength (absorption peak)
- both found at the centre of photosystems
(primary pigment reaction centre)
- P680 is in photosytem 2 and
its peak absoption is 680 nm
- P700 is in photosystem 1 and
its peak absoption is 700 nm
- both also absorb blue light
of wavelength 450 nm
- chlorophll B absorbs light of
wavelengths around 500 and 640 nm
- appears blue-green
- Accessory
pigments
- carotenoids reflect orange and
yellow light and absorb blue
- carotene (orange) and xanthophyll
(yellow) are the main carotenoid pigments
- don't contain a porphryin group
- they're not directly involved in
the light dependant reaction
- they pass the energy associated with wavelengths that are
not well absorbed by chlorophyll to the primary pigment