2-4 Chemical Reactions and Enzymes p50 Q: What happens to chemical bonds during chemical reactions? A: Chemical reactions involve changes in the chemical bonds that join atoms in compounds.

Reactants-what goes in. Products-what comes out. 2H + 0 Chemical Reactions Reactants-what goes in. Products-what comes out. 2H + 0 H2 O Reactant Product

Energy in Reactions Q: How do energy changes affect whether a chemical reaction will occur? A: Chemical reactions that release energy often occur on their own, or spontaneously. Chemical reactions that absorb energy will not occur without a source of energy.

Energy Changes- release (occur on own) and absorb energy (energy needed) Activation Energy- Energy needed to get reaction started

Activation Energy Push cart. Takes a lot of energy to get started. Take the break off cart & push. Takes less energy to get started because the activation energy was lowered by taking off the break. The enzyme acts like taking off the break.

Enzymes Q: What role do enzymes play in living things and what affects their function? A: Enzymes speed up chemical reactions that take place in cells. Temperature, pH, and regulatory molecules can affect the activity of enzymes.

Enzymes-proteins that act as biological catalysts. Catalyst-speeds up rate of reaction.

Enzyme Action Substrate-reactant of the enzyme-substrate complex The Enzyme-Substrate Complex is like a Lock & Key. The enzyme can be reused. 1.substrates come together 2 can be reused 4 3

Regulation of Enzyme Activity Room temperature is best. Higher & lower slows down the reaction. Change in pH slows down the reaction. Both of these destroy the shape of the active site. https://www.youtube.com/watch?v=XTUm-75-PL4 https://www.youtube.com/watch?v=NdMVRL4oaUo