factors affecting enzyme concentration. 2 of 34© boardworks ltd 2008 enzymes: true or false?

Factors affecting enzyme concentration

2 of 34 © Boardworks Ltd 2008

Enzymes: true or false?


• Spec Check

• explain the importance of cofactors and coenzymes in enzyme-controlled reactions;

•


What are cofactors?

Some enzymes require the addition of a non-protein substance called a cofactor before they can catalyze a reaction. There are two main types of cofactor:

activators – inorganic groups that are permanently bound to the enzyme and so are a type of prosthetic group. Common examples include iron, zinc and copper.

coenzymes – organic molecules that bind only temporarily to the enzyme, transferring a chemical group necessary required for the reaction. Examples include vitamin C and ATP.

vitamin C


• Spec Check

• describe and explain the effects of pH, temperature, enzyme concentration and substrate concentration on enzyme activity;

• describe how the effects of pH, temperature, enzyme concentration and substrate concentration on enzyme activity can be investigated experimentally;

•


• Enzyme Experiments

• Measuring effects on enzymes:• Measure the amount of product made or

substrate used up.Can be done by

Measuring the amount after a fixed period

Measuring the amount at pre-determined time intervals

If you measure time taken for something you can then calculate the rate of reaction by 1/time


• Next....

• Plot a graph

Independent variable

Rat

e of

rea

ctio

n


• Controlled factors in experiments

• Equilibration – incubating the substrate and the enzyme before the start of the experiment to ensure they reach the required temperature before the experiment begins

• Control all other factors except the one being investigatedEg accurate measurements, temperature, pH


• Calculating initial rate

• This is important if you want to compare the rate of a reaction with the rate after a factor has been altered.


Measuring the initial rate of reaction


TemperatureEffect

Explanation

Measuring Activity

Enzyme ConcentrationEffect

Explanation

Measuring Activity

pHEffect

Explanation

Measuring Activity

Substrate ConcentrationEffect

Explanation

Measuring Activity

Explaining and measuring enzyme activity


Effect of temperature on enzymes


Effect of pH on enzymes


Rate of reaction experiment


Effect of substrate concentration on rate


Effect of enzyme concentration on rate


• Now complete the rest of the table

• Use the activity sheet pack per group• Use p142-3 in purple books• Use p 138 in green books

• You must know a method to measure enzyme activity for each factor


Factors affecting rate of reaction


• Spec Check

• (f) explain the effects of competitive and non-competitive inhibitors on the rate of enzyme-controlled reactions, with reference to both reversible and non-reversible inhibitors;

• (g) explain the importance of cofactors and coenzymes in enzyme-controlled reactions;

• (h) state that metabolic poisons may be enzyme inhibitors, and describe the action of one named poison;

• (i) state that some medicinal drugs work by inhibiting the activity of enzymes (HSW6a).

•

factors affecting enzyme concentration. 2 of 34© boardworks ltd 2008 enzymes: true or false?

Documents

rate slide

enzyme activity slide

enzyme concentration

ph slide

time slide

effect of enzyme concentration

initial rate of reaction

enzyme experiments