Question

1. Cyanobacteria and plants are photosynthetic organisms but their photosynthesis pathway are not identical.

(a) You are required to summarize the major events (carbon fixation, electron transport chain) in cyanobacteria. The details of the summary should be concise and informative. The length of the summary should be less than 200 words.  

(b)       Summarize how photosynthesis in bacteria is different from photosynthesis in plant.

(c)        NAD and NADP are important molecules in plant cells. Describe in details the role of these molecules within a plant cell.

Answer 1

a) carbon fixation: cyanobacteria utilizes the energy of sunlight to continue photosynthesis in which the energy of light is used to synthesize organic compounds from CO2. Since cyanobacteria are aquatic organisms they use several strategies which together are known as carbon concentrating mechanism which helps in the acquisition of inorganic carbon.

Electron transport chain: the phycobilisome acts as light-producing antennae for the photosystems and is attached to the thylakoid membrane of cyanobacteria. These phycobilisomes are responsible for the blue-green pigmentation of the cyanobacteria.

b) Photosynthesis that occurs in cyanobacteria is oxigenic, which means they produce oxygen at the end of photosynthesis as most cyanobacteria are autotrophs. They contain chlorophyll similar to plants and also possess photosynthetic water-soluble pigments known as phycobilins. Starch is the reserve food material in cyanobacteria. Whereas, photosynthesis in bacteria is an-oxygenic because they are heterotrophs and do not prepare their own food and photoautotrophic bacteria do not contain phycobilins because bacteria are heterotrophs. The reserve food material is glucogen.

c) Role of NAD in plants: Nicotinamide Adenine Dinucleotide is used by all living cells as a cofactor in energy transfer. NAD is a pyridine nucleotide whose main function is the transport of electrons with-in oxidation-reduction or better known as redox reactions and besides they also are an important component in cellular signaling.

Role of NADP in plants: the main of Nicotinamide Adenine Dinucleotide Phosphate is that it acts like a co-enzyme in cellular electron transport reactions. It also possesses some other functions such as storing the energized electron for a temporary period of time and NADP also functions as an electron carrier in cellular respiration.