The human digestive system

Question 1

What are enzymes made of

‘the nature of enzymes’

Answer 1

Enzymes are proteins made out of polymers of amino acids

Question 2

What are enzymes

define an ezyme

Answer 2

Enzymes are biological catalysts which increase the rate of chemical reations

Question 3

Explain the enzyme ‘lock and key’ theory

Answer 3

The enzyme is the lock and the substrate is the key.

The enzyme has a uniquely shaped active site- shape of active site and the specific substrate are complimentary to each other like a lock and key.

The substrate will bind to the active site to form the enzyme/substrate complex.

Then a chemical reaction occurs and the enzyme breaks the substrate down to produce smaller molecules.

Question 4

Name the three different enzymes

Answer 4

Amylase

Lipase

Protease

Question 5

Name the sites in the body where amylase is produced

Answer 5

1. Salivary glands
2. Pancreas
3. Small intestine

Question 6

Name the sites in the body where lipase is produced

Answer 6

1. Small intestine
2. Pancreas

Question 7

Name the sites in the body where protease is produced

Answer 7

1. Stomach
   2.Small intestine
2. Pancreas

Question 8

What is the function of amylase?

Answer 8

Breaks down starch into simple sugars

Question 9

What is the function of the lipase enzyme

Answer 9

Breaks down fats (lipids) into fatty acids and glycerol

Question 10

What is the function of the protease enzyme?

Answer 10

Breaks down proteins into amino acids

Question 11

Where is bile produced?

Answer 11

Bile is produced in the liver (stored in the gall bladder)

Question 12

Where is bile stored

Answer 12

Bile is stored in the gall bladder

Question 13

Name the two funtions of bile

Answer 13

Neutralises stomach acid

Emulisifes fats

Question 14

Describe how bile neutralises stomach acid

Answer 14

1. The stomach has a slightly acidic pH as it produces hydrochloric acid, this means that when the food travels to the small intestines, it is acidic.
2. The bile travels from the gall bladder to the top of the small intestines
3. The bile is alkeline, so it neutralises the acid so that the enzymes can work at their optimum pH in the small intestines.

Question 15

Describe how bile emulisifies lipids

Answer 15

Bile emulsifies lipids (fats) by breaking them down into smaller fat droplets

This increases the surface area of the fats so that the lipase enzyme can break down fats into fatty acids and glycerol at a faster rate.

Question 16

What solution is used to test for reduced sugars?

Answer 16

Benedicts solution

Question 17

Suggest why a Benedict’s solution will not work for sugars like sucrose?

Answer 17

Becuase sucrose is a non-reduced sugar (as opposed to a reduced sugar for which the test works)

Question 18

How does temperature affect enzyme activity?

Answer 18

As the temperature increases, the activity of the enzyme increases

Because the increased temperature causes the enzyme and the specific substrate to have an increased kintetic energy and move faster, which increases the frequency of collisions between the substrate and the active site

Question 19

What is the optimum temperature for an enzyme?

Answer 19

The temperature at which the enzymes are working at the fastest possible rate

So there is the maximum freuquency of successful collisions between the substrate and the active site

Question 20

What happens to an enzyme when the temperature is increased aboved optimum temperature?

Answer 20

The enzyme becomes denatured

This changes the shape of the active site, so the specific substrate will not be able to bind into it anymore

Question 21

What is meant by the optimum pH for an enzyme?

Answer 21

Where the activity of the enzyme is maximum

Question 22

What happens when the pH is too acidic or too alkaline for a certain enzyme?

Answer 22

The enzyme will become denatured

Question 23

All enzymes have their own specific optimum pH’s

TRUE or FALSE?

Answer 23

True

Question 24

In which site in the body might an enzymes specific optimum pH be acidic?

And which enzyme?

Answer 24

In the stomach (because it is acidic here)
Protease