Enzymes 12/15

allosteric site

A region on the enzyme that a regulatory molecule can bind to. when regulatory molecule binds to allosteric site it changes the enzyme's shape, which prevents substrate from binding to active site

effect of cold temperatures on enzymes

Cold temperatures decrease the rate of reaction because molecules are moving slower and are less likely to collide, but cold temperatures do not denature the enzyme, so if the temperature is brought back up, the chemical reaction will speed back up to a normal process.

lock and key model

explains the specificity of enzymes. the substrate is the key which can only fit into a certain lock, the active site of the enzyme

enzymes

proteins in cells that catalyze (lower the activation energy of a chemical reaction and speed up) reactions. Many chemical reactions would not proceed without enzymes, and therefore cells are dependent on enzymes to carry out essential life functions

enzyme-substrate complex

the enzyme and the substrate combined

Are enzymes very specific to a specific substrate?

yes, enzymes only bind a specific substrate within their active site forming the enzyme substrate complex

How are enzymes named?

They usually end with -ase. Ase is frequently added onto the end of a substrates name. ex- the substrate maltose is broken down into glucose molecules. The enzyme responsible for this reaction is maltase

cofactors

atoms or molecules that are not part of the enzyme structure but are often required for an enzyme to function properly. vitamins are needed for the production of cofactors, so a deficiency in vitamins leads to a deficiency in cofactors which leads to deficient enzymes which leads to disease

How do enzymes affect activation energy?

Enzymes are catalysts, so they affect activation energy by decreasing the required amount of activation energy allowing chemical reactions to occur or speed up. It does not affect the amount of energy that is released by the reaction.

Are enzymes reusable? And do enzymes change in chemical reactions?

yes, no

What is crucial to an enzyme's function?

The three dimensional structure of enzymes

What does the enzyme accomplish by binding to substrate?

When a substrate binds to the active site it changes the enzyme's shape slightly, which puts strain on the bonds of the reactant molecules. This weakens the bonds so less energy is required to break the bonds

competitive inhibition

a chemical that closely resembles the shape of the substrate of an enzyme, which competes with the substrate for binding to the active site

Amount of energy required to get a chemical reaction started is called

activation energy

Why do you need energy to get a chemical reaction started?

activation energy is needed to break the bonds of reactant molecules so they can rearrange and form new bonds (get to the transition state) . On modern Earth, living things get their energy from other molecules (food). ATP is the molecule organisms can use directly for energy

effect of pH on enzymes

decreasing or increasing pH can denature an enzyme and the function will be lost each enzyme has an optimum pH that it works best at, most work best around 7.4

induced fit model

explains how enzymes weaken bonds of reactants and thus decrease the amount of activation energy needed. proposes the idea that after the substrate binds to the active site, the enzyme changes its shape slightly to obtain a more firm grip on the molecules, which causes strain on the bonds and breaks them apart, allowing less energy to be used to break old bonds and generate new ones

How does increasing the amount of substrate or enzyme affect the rate of a chemical reaction?

if you add more substrates, but all available enzymes are being used, then this will not speed up the reaction because there is no active site for the new substrates to bind with, but adding more enzymes will speed up the reaction in this case or if not all the enzymes are being used then adding more substrate will speed up the reaction

effect of hot temperature on enzymes

increasing temperature speeds up chemical reactions due to increased movement of molecules and increased likelihood of collisions up to a point before the enzymes are denatured, which cause enzymes to permanently lose their function

How does activation energy serve as a barrier to chemical reactions?

it serves as a barrier to the chemical reaction occurring or occurring very slowly. This is because chemical reactions within a cell do not proceed unless enough activation energy is available

substrate

the reactant molecule(s) that an enzyme acts on. (the piece that fits into the active site)

active site

the region of the enzyme that binds with the substrate