1. Photosynthetic organisms have mechanisms to protect the photosynthetic light reaction from environmental stresses. Take one...

1. Photosynthetic organisms have mechanisms to protect the photosynthetic light reaction from environmental stresses. Take one or two examples for this, and explain the mechanism briefly.

2. Summarize how reactive oxygen species are generated in living cells and how they damage cell components and bio-molecules.

Solutions

Expert Solution

1. Photosynthetic light reaction are done by photosynthetic pigments like chlorophyll a, chlorophyll b, xanthophyll and carotenoids. Chlorophyll a forms the reaction centre( major pigment responsible for light trapping) and other pigments form a ' antennae' which also absorb light and transfer the energy to chlorophyll a.

Protection from environmental stresses:

------> It enable a wider range of wavelength of incoming light to be utilized for photosynthesis. In case of low light, plants are able to synthesize food.

------> it also protect chlorophyll a from photo-oxidation.

2. reactive oxygen species can be produced by metal toxicity, ionising radiation (UV-B) or heat exposure.

Damaging effects: a). Damage DNA or RNA.

b). lipids peroxidation.

c). amino acid oxidation.

d). oxidation of co-factors, etc.

gladiator answered 1 year ago

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