Explain the chemical process of the fixation of carbon dioxide (CO₂) to an existing carbon chain such as Ribulose-1,5-bisphosphate carboxylase-oxygenase. In your answer be sure to address the following details.

• which carbon is acting as the electrophile and which carbon is acting as the nucelophile
• is this process exergonic or endergonic in relation to the G of this reaction
• which enzyme(s) would be responsible for catalyzing this reaction