Chap 8 Slide Notes - Biology PDF

## **AG (free energy)** - The higher the G the more unstable the system. - A change in free energy can occur w/ metabolism. **Exergonic:** reactions that lose energy; -AG **Endergonic:** reactions that gain energy; + AG - When AG=0 no work can be done. - When we get to equilibrium, AG=0 We can't...

## **AG (free energy)** - The higher the G the more unstable the system. - A change in free energy can occur w/ metabolism. **Exergonic:** reactions that lose energy; -AG **Endergonic:** reactions that gain energy; + AG - When AG=0 no work can be done. - When we get to equilibrium, AG=0 We can't do/make anything! - Energy is always needed for mechanical, chemical, and transport workings of the cell. ## **ATP** - A nucleotide made up of sugar, phosphate group, and a nitrogenous base. - Nucleotide w/ three phosphate groups attached to the ribose sugar. - Energy molecule used to couple exergonic reactions to endergonic reactions. - ATP has a high ΔG. - Energy is released from ATP through the loss of phosphate groups. - Catabolic reaction resulting from hydrolysis producing ADP + P₁ (inorganic Phosphate) + energy - (AG-7.3Kcal/mol in the lab, -13Kcal/mol in the cell) ## **-How ATP Works:** - Hydrolysis of ATP produces inorganic phosphate that is attached to a molecule involved in an endergonic process. - Phosphorylation: The process of ATP transferring phosphate to a molecule which results in a phosphorylated intermediate that can complete the intended reaction. ## **Regeneration of ATP** - ATP loses energy when it phosphorylates an intermediate molecule of an endergonic reaction. ATP becomes ADP. ## **Enzymes** - Make sure reactions occur. - Proteins that assist in chemical reactions may be enzymes. - Specific because of conformational shape. - Lower amount of energy used to create reaction. - **Catalyst**: chemical that changes the rate of a reaction without being consumed. ## **Activation Energy** - Activation energy: Minimum amount of energy needed for a chemical reaction to start. ## **How Enzymes Work** - **Enzymes** are **substrate specific**. - **Substrate:** any molecule to which an enzyme will bind to. - Only **active site** interacts w/ the substrate. - Enzyme's shape modifies to better fit the substrate. - **Induced fit:** Where enzyme changes its shape to mold around the substrate better. - Termination products have lower affinity for active site and are released. Enzyme is unchanged after the reaction. ## **Enzyme Activity** - The rate of an enzyme catalyzed reaction is influenced by: - Concentration of the substrate - Enzyme concentration - Some enzymes utilize - Inorganic molecules - Organic molecules as helpers - **Cofactor:** inorganic molecule (mineral) - **Coenzyme:** organic, non-protein molecule (vitamin) - The rate at which an enzyme can function is dependent on the physical factors: - Temperature - pH ## **Enzyme Regulation** - Activity may be reduced (or stimulated) by molecules attaching to the enzyme. ## **Maximize Cellular Efficiency** - ATP is...