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Enzymes are what?

Globular proteins that work as catalysts - they speed up chemical reactions without being altered themselves (biological catalysts)


What are the substances that enzymes convert into productions called?



What is enzyme- substrate specificity?

Many enzymes are needed as enzymes only catalyse one biological reaction


Where do the substrates bind?

To a special region on the surface of the enzyme called the active site


Why are the 3 stages of a catalysis reaction by an enzyme

1)the substrate binds to the active site of the enzyme.
2) while the substrates are bound to the active site they change into different chemical substances
3) the products separate from the active site, leaving it vacant for substrates to bind again


What is the coming together of a substrate molecule and an active site known as?



The collisions between substrate molecules and the active site occur because of random movements to both substrate and enzyme why

Most reactions occur in dissolved water so molecules are in contact with each other and are in continual motion


What 3 factors effect enzyme activity?

Temperature, pH and substrate concentration


Enzymes are affected by temperature in 2 ways- what is the first?

When a liquid is heated, particles in it are given more kinetic energy - therefore both enzyme and substrate molecules move around faster therefore more of a chance of collision - enzyme activity increases


Enzymes are affected by temperatures in 2 ways- what is the 2nd?

When enzymes are heated, bond in the enzyme vibrate more and the chance of the bonds breaking is increased. When bonds in the enzyme break the structure of the active site changes - this change is permanent and called denaturation - makes enzyme activity fall


What is the effect of pH on enzyme activity?

Most enzymes have an optimum pH at which there activity is highest, if the pH is increased or decreased from the optimum, enzyme activity decreases and eventually stops all together - alters active site - denaturation


How is enzyme activity affected by substrate concentration?

If the concentration of substrates increases, substrate-active site collisions will take place more frequently and the rate at which the enzyme catalyses it's reaction increases- however if continues to rise the sites become occupied to activity decreases


When an enzyme has been denatured what happens?

The active site is altered so the substrate can no longer bind,


Immobilised enzymes are widely used in what?



What is an immobilezed enzyme?

Attachment of the enzymes to another material or into aggregations so that movement of enzymes is restricted


What are the 4 advantages of enzyme immobilisation?

1) the enzyme can easily by separated from the products of the reaction, stopping the reaction at an ideal time and preventing contamination of the products
2) after being retrieved from the reaction mixture the enzyme may be recycled = cost saving
3) immobilisation increases the stability of enzymes to changes in temp, pH etc
4) substrates can be exposed to higher enzyme concentrations than with dissolved enzymes, speeding up reaction rate


Enzymes have an active site to which what binds to?

Specific substrates bind

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