B4 - Enzymes

Question 1

What is the process when an enzyme’s active site deforms?

Answer 1

It is denatured.

Question 2

What is an active site?

Answer 2

The active site is the specific region of the enzyme which combines with the substrate. Only specific substrate molecules fit into specific enzymes.

Question 3

What enzymes digest proteins?

Answer 3

protease break down protein into amino acids

Question 4

What enzymes break down starch?

Answer 4

Amylase break down starch into simpler sugars such as maltose

Question 5

What enzymes break down fats?

Answer 5

Lipase break down fats into fatty acids and glycerol

Question 6

Where is carbohydrase made?

Answer 6

It is made in the salivary glands, pancreas and small intestine.

Question 7

What is it that makes the enzymes meet the molecules they are meant to digest?

Answer 7

Random movement.

Question 8

How would an enzyme become denatured?

Answer 8

The ph is too acidic or alkaline. Also, it can denature if the temperature is too high.

Question 9

What is a catalyst?

Answer 9

A catalyst is a substance which increases the speed of a reaction, without being changed or used up in the reaction

Question 10

What are enzymes made of?

Answer 10

Enzymes are all large proteins and all proteins are made of chains of amino acids which are folded up into unique shapes, which enzymes need to do their jobs

Question 11

What is the substance that an enzyme acts on called?

Answer 11

A substrate

Question 12

How do enzymes work?

Answer 12

1 - every enzyme has an active site with a unique shape that fits the substrate.
2 - the enzyme will meet the substrate it reacts with by random movement
3 - The enzyme changes shape slightly to create a tight fit
4 - The enzyme speed up the reaction of the substrate into its products
5 - The products leave the active site

Question 13

What is metabolism?

Answer 13

Enzymes control metabolism - the sum of all the reactions in a cell or in the body

Question 14

Why do enzymes need to break up food?

Answer 14

Starch, proteins and fats are big molecules. They are too big to pass the walls of the digestive system so they need to be broken up into smaller solvable molecules

Question 15

What is the effect of temperature on enzyme activity?

Answer 15

At low temperatures, the rate of enzyme reaction is low. However, as the temperature increases, the rate of enzyme reaction increases.

Question 16

Why does the rate of enzyme reaction increases when the temperature increases?

Answer 16

Because at higher temperatures, the enzyme and substrate molecules move faster, increasing the force and the rate of collision. Reactions also occur more frequently.

Question 17

Why does the rate of enzyme reaction decrease when the temperature decreases?

Answer 17

Because the enzyme and substrate molecules move slower, decreasing the force and the rate of collision.

Question 18

What is the optimum temperature for an enzyme?

Answer 18

37 degrees Celsiuis

Question 19

What happens to enzymes at high temperatures (above 40 degrees Celsius)?

Answer 19

Enzymes (being proteins) become denatured rapidly due to changes in the shape of the enzyme molecules. The substrate molecules cannot attach themselves to the newly shaped active site of the enzyme molecule.
The enzyme becomes functionless.

Question 20

What is the optimum pH level for an enzyme?

Answer 20

pH = 7

Question 21

What happens when the enzyme’s reaction medium becomes too acidic or alkaline?

Answer 21

An enzyme that functions at pH = 7, will become inactive when it is too acidic or alkaline.

Question 22

What does a change in pH in an enzyme equal?

Answer 22

A change in pH results in a change in the concentration of hydroxide ions and hydrogen ions. The excess hydrogen ions destabilise the enzyme by changing the shape of the active site and the enzyme stops functioning.

Question 23

How can an enzyme in a low pH be active again?

Answer 23

The effects of changes in pH on the activity of enzymes are often reversible. An enzyme that is inactive at a low pH will be active again when it is at its optimum pH.