Q: Identify why rubisco has a low catalytic rate. 9. Describe two ways plants limit the formation and effects of reactive oxygen species.

The reason rubisco has a catalytic rate is because it is a relatively slow enzyme that evolved primarily for its ability to fix carbon dioxide efficiently under the conditions of early Earth rather for speed. Explanation Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) is essential for the Calvin cycle in photosynthesis, catalyzing fixation of CO₂. low catalytic rate is a consequence of dual activity—also catalyzing a reaction with oxygen (photorespiration)—which its efficiency. Evolutionarily, rubisco's site optimized for CO binding, but can also bind oxygen, leading to photorespiration, a wasteful process. Additionally, the enzyme's structure and active site are not optimized for rapid turnover, partly because of the need to maintain specificity and prevent unwanted reactions, inherently limits its speed. Two ways plants limit the formation and effects of reactive oxygen speciesROS): Antioxid Enzymes Plants produce enzymes such as superoxide dismutase (SOD), catalase, and ascorbate peroxidase that detoxify ROS. oxide dismut converts superoxide radicals ( _2^-) into hydrogen peroxide (H2O_2). Catalase then breaks down hydrogen peroxide into water and oxygen, preventing of harmful ROS. Non-Enzymatic AntioxidPlants also synthesize molecules like ascorbic acid (vitamin C),athione, and carotids that scge ROS directly. These neutralize ROS donating electrons, thereby preventing damage to cellular such lip, proteins, and DNA. Summary:** Rubisco's low catalytic rate is due to its evolutionary trade between speed and, especially its oxygenase activity leading to photorespiration. Plants mitigate ROS damage through enzymatic antioxidants and-enzymatic molecules, maintaining cellular health under stress conditions.

Question

Identify why rubisco has a low catalytic rate. 9. Describe two ways plants limit the formation and effects of reactive oxygen species.

Accepted Answer

The reason rubisco has a catalytic rate is because it is a relatively slow enzyme that evolved primarily for its ability to fix carbon dioxide efficiently under the conditions of early Earth rather for speed.

Explanation

Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) is essential for the Calvin cycle in photosynthesis, catalyzing fixation of CO₂. low catalytic rate is a consequence of dual activity—also catalyzing a reaction with oxygen (photorespiration)—which its efficiency. Evolutionarily, rubisco’s site optimized for CO binding, but can also bind oxygen, leading to photorespiration, a wasteful process. Additionally, the enzyme’s structure and active site are not optimized for rapid turnover, partly because of the need to maintain specificity and prevent unwanted reactions, inherently limits its speed.

Two ways plants limit the formation and effects of reactive oxygen speciesROS):

Antioxid Enzymes

Plants produce enzymes such as superoxide dismutase (SOD), catalase, and ascorbate peroxidase that detoxify ROS.

oxide dismut converts superoxide radicals ($\\{_2^-}$) into hydrogen peroxide ($\\mathrm{H2O_2}$).
Catalase then breaks down hydrogen peroxide into water and oxygen, preventing of harmful ROS.

Non-Enzymatic AntioxidPlants also synthesize molecules like ascorbic acid (vitamin C),athione, and carotids that scge ROS directly.

These neutralize ROS donating electrons, thereby preventing damage to cellular such lip, proteins, and DNA.

Summary:**
Rubisco’s low catalytic rate is due to its evolutionary trade between speed and, especially its oxygenase activity leading to photorespiration. Plants mitigate ROS damage through enzymatic antioxidants and-enzymatic molecules, maintaining cellular health under stress conditions.