Chapter 2 - Enzymes

Question 1

Enzymes are what?

Answer 1

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

Question 2

What are the substances that enzymes convert into productions called?

Answer 2

Substrates

Question 3

What is enzyme- substrate specificity?

Answer 3

Many enzymes are needed as enzymes only catalyse one biological reaction

Question 4

Where do the substrates bind?

Answer 4

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

Question 5

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

Answer 5

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

Question 6

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

Answer 6

Collision

Question 7

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

Answer 7

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

Question 8

What 3 factors effect enzyme activity?

Answer 8

Temperature, pH and substrate concentration

Question 9

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

Answer 9

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

Question 10

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

Answer 10

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

Question 11

What is the effect of pH on enzyme activity?

Answer 11

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

Question 12

How is enzyme activity affected by substrate concentration?

Answer 12

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

Question 13

When an enzyme has been denatured what happens?

Answer 13

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

Question 14

Immobilised enzymes are widely used in what?

Answer 14

Industry

Question 15

What is an immobilezed enzyme?

Answer 15

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

Question 16

What are the 4 advantages of enzyme immobilisation?

Answer 16

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

Question 17

Enzymes have an active site to which what binds to?

Answer 17

Specific substrates bind