4.1 Enzyme Action

Question 1

What are enzymes? What do they do?

Answer 1

Enzymes are biological catalysts, (globular proteins) that interact with substrate molecules, increasing the rate of reaction

Question 2

What is metabolism?

Answer 2

Sum of all reaction pathways occurring in an organism

Question 3

What factors affect the rate of cellular (chemical) reactions?

Answer 3

Temperature, pressure, pH

Question 4

What is the Vmax

Answer 4

The point up to which enzymes can increase the rate of reaction

Question 5

What is the specificity of an enzyme?

Answer 5

The concept that each enzyme can catalyse only one biochemical reaction

Question 6

What is activation energy?

Answer 6

Amount of energy needed to start a reaction

Question 7

What is the active site?

Answer 7

An area within tertiary structure of enzyme with complementary shape to a specific substrate molecule

Question 8

What is the idea behind the lock and key hypothesis?

Answer 8

Only a specific substrate will fit into the active site of an enzyme

Question 9

What do you call it when a substrate is bound to the enzyme’s active site?

Answer 9

Enzyme-substrate complex

Question 10

What is the enzyme-substrate complex?

Answer 10

When the substrate is bound to its complementary active site

Question 11

What is an enzyme-product complex?

Answer 11

Formed when substrates react, and the products are formed in an enzyme-product complex

Question 12

What are the stages in the lock and key hypothesis?

Answer 12

1. Substrate binds to complementary active site, forming enzyme-substrate complex
2. Substrate reacts and products are formed in enzyme-product complex
3. Products are released, leaving enzyme unchanged

Question 13

What is the idea behind the induced-fit hypothesis?

Answer 13

Enzyme’s active site changes shape as the substrate enters

Question 14

Where do intracellular enzymes react?

Answer 14

Inside cells

Question 15

Where is catalase found?

Answer 15

Plant and animal tissues

Question 16

What is the role of catalase?

Answer 16

H peroxide is a toxic product of metabolic pathways; catalase ensures it’s broken down to O2 + H20 quickly, preventing its accumulation

Question 17

Where do extracellular enzymes react?

Answer 17

Outside of the cells that made them

Question 18

State the name of 2 extracellular enzymes involved in human digestion

Answer 18

Amylase, trypsin

Question 19

Where does the digestion of starch occur?

Answer 19

Digestion of starch begins in mouth and continues in small intestine

Question 20

What are the 2 steps in the digestion of starch?

Answer 20

1. Starch polymers are partially broken down into maltose, a disaccharide, catalysed by amylase
2. Maltose is broken down into glucose, a monosaccharide, catalysed by maltase

Question 21

Where is amylase produced?

Answer 21

Salivary glands and pancreas

Question 22

Where is amylase released after being produced?

Answer 22

Saliva or pancreatic juice into small instestine

Question 23

Where is maltase found?

Answer 23

In small intestine

Question 24

What is type of enzyme is trypsin? What is its function?

Answer 24

Protease - catalyses digestion of proteins into smaller peptides, which are broken down into amino acids

Question 25

Where is trypsin produced?

Answer 25

Pancreas

Question 26

Where is trypsin released?

Answer 26

Released with pancreatic juice into small intestine

Question 27

What absorbs the nutrients in small intestines?

Answer 27

Cells lining digestive system