Photorespiration

Videonummer 11937772

Photorespiration, animation. This process occurs when oxygen is fixed instead of carbon dioxide in one of the steps of the Calvin cycle. The products of this oxygen fixation are 3-phosphoglycerate (3-PG), which enters the Calvin cycle, and phosphoglycolate, which is an inhibitor of photosynthesis. The phosphoglycolate is converted to glycolate and moved to a peroxisome. Here it is oxidised to glyoxylate and then converted to the amino acid glycine. Glycine is transported to a mitochondrion. Two glycine molecules are converted to one serine molecule by the enzyme gylcine-decarboxylase. This process releases carbon dioxide and ammonia, and reduces NAD to NADH. Serine is transported to the peroxisome where it loses its amino group to give hydropyruvate, which is then reduced to glycerate. Glycerate is transported to the chloroplast and converted to 3-PG by the hydrolysis of an ATP molecule. Photorespiration therefore consumes ATP, rather than producing it as the Calvin cycle does.
Lizenzart:	Lizenzpflichtig
Credit:	Science Photo Library / Biocosmos / Francis Leroy & Edwin Vandermeeren
Modell-Rechte:	nicht erforderlich
Länge:	01:20 Minuten
Seitenverhältnis:	16:9
Restrictions:	-

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