Chapter 5.5 Summary

Enzymes are proteins that speed up specific reactions in cells.

Enzymes and Activation Energy

activation energy

: energy needed to start a chemical reaction

- one way is to heat up the mixtures of molecules but may cause other reactions to happen at once

catalysts

: compounds that speed up chemical reactions

enzymes

: specialized protein that catalyzes the chemical reactions of a cell

- provides a way for chemical reaction to occur at the cell's normal temperature

- lowers energy requirements barrier

- each enzyme catalyzes a specific chemical reaction

How Enzymes Work

substrate

: specific reactant acted on by an enzyme

active site

: region of an enzyme into which a particular substrate fits

- changes to fit substrate more snugly when it enters

- adding a molecule added to weakened bond to break the bond

- a key characteristic of enzymes is its recycling ability

- holding two substrates into adjacent sites allows them to react more easily

- enzyme's shape is sensitive to its surrounding environment

ex. pH, temperature

Concept Check

1. Explain the role of activation energy in a reaction. How does an enzyme affect activation energy?
   The role of activation energy in a reaction is to start the reaction. An enzyme reduces the activation energy needed to trigger the reaction.
2. Describe how a substrate interacts with an enzyme.
   A substrate would first bing to an enzyme with empty active site. The grip of the enzyme on the substrate weakens then breaks the bond of the substrate. The products are then released turing the substrate into the molescules it formed from.