RuBP Oxygenation Products in Photorespiration
Photorespiration is triggered under conditions favouring oxygenation over carboxylation, specifically when $CO_2$ levels are low and $O_2$ levels are high.
The key enzyme involved is RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase). In photorespiration, RuBisCO acts as an oxygenase, reacting with ribulose 1,5-bisphosphate (RuBP) and molecular oxygen ($O_2$).
This enzymatic reaction directly yields:
- One molecule of 3-phosphoglycerate (3-PGA)
- One molecule of 2-phosphoglycolate
Therefore, the reaction of $O_2$ with ribulose 1,5-bisphosphate produces one molecule each of 3-phosphoglycerate and 2-phosphoglycolate.
Important Questions from Photosynthesis Respiration and Electron Transport Chain
- Correctly match the Inhibitor with its respective Function in mitochondrial respiration.
Inhibitor Function P. FCCP 1. Inhibits cytochrome c oxidase Q. Cyanide 2. Makes the membrane permeable to protons R. Oligomycin A 3. Blocks mitochondrial uptake of succinate S. Butyl malonate 4. Inhibits ATP synthase Which of the following are true with regard to anaerobic respiration in bacteria?
P. The final electron acceptor is an inorganic substance other than molecular oxygen
Q. The number of ATP molecules produced per glucose molecule is more than that produced in aerobic respiration
R. The number of ATP molecules produced per glucose molecule is less than that produced in aerobic respiration
S. Only substrate level phosphorylation is used to generate ATP
- ATP biosynthesis takes place utilizing the $H^+$ gradient in mitochondria and chloroplasts. Identify the correct sites of $H^+$ gradient formation.
Match the compounds in Group I with the correct entries in Group II.
Group I Group II P) Cyanide 1) K$^+$ ionophore Q) Antimycin A 2) Electron transfer from cytochrome b to cytochrome c$_1$ R) Valinomycin 3) F$_1$ subunit of ATP synthase S) Aurovertin 4) Cytochrome oxidase 5) Adenine nucleotide translocase Match items in Group I with Group II.
Group I Group II
P. Glycolytic pathway 1. Chloroplast
Q. Eukaryotic oxidative metabolism 2. Glyoxysomes
R. Glyoxylate cycle 3. Mitochondria
S. Calvin cycle 4. Cytosol
