Chapter Five Concept 5.5

Enzymes are proteins that speed up specific reactions in cells. 

Enzymes and Activation Energy:

-to start a chemical reaction, first weaken chemical bond in reactant molecules.

-activation process requires molecules to absorb energy.

Activation Energy: minimum amount of energy required to trigger a chemical reaction.

-to provide activation energy: add heat the mixtures of molecules.

-hotter molecules collide with energy to weaken bonds, but cooler molecules .

-heating cell can cause many unnecessary reactions to occur at once, which results to destruction of cell's delicate structures. 

Catalysts: compounds that speed up chemical reactions.

Enzymes: catalysts of chemical reactions in organisms that are specialized protons.

-provides a way for reactions to occur at cell's normal temperature.

-enzymes don't supply activation energy to reacting molecules, but lowers the energy required so the reaction can proceed.

-enzyme catalyzes specific kinds of chemical reactions.

How Enzymes Work: 

-enzymes fit in the shape of particular reactant molecules.

Substrate: specific reactant acted on by an enzyme.

Active Sit: region of an enzyme into which a particular substrate fits.

-fit between substrate and enzyme is not rigid.

-when substrate enters active site, it changes its shape to fit into the substance perfectly.

-sucrose is slightly distorted when entering the active site.

-weakened bond reacts with water, result: a glucose molecule and fructose molecule.

-if either one of the results are released, the enzyme active site would accept another sucrose molecule. 

-to keep enzymes with lower activation energy is to accept two reactant molecules.

-enzymes structure and shape are essential to its function.

-factors such as pH and temperature is greatly affected.

-cells can only survive and function within certain ranges of conditions. 

Concept Check 5.5:

1. Explain the role of activation energy in a reaction. How does an enzyme affect activation energy? 

The activation energy in a reaction is significant because it is a start up to a reaction, and triggers a chemical reactions, which starts up the whole reaction. And enzyme affects activation energy by lowering the energy required so the reaction can proceed at normal cell temperatures.

2. Describe how a substrate interacts with an enzyme.

A substrate helps an an enzyme to fit into a particular region of an active site by slightly changing its shape to make it fit more snugly to to the active site.