Module 2 Section 4 - Action of Enzymes

Question 1

What do enzymes do

Answer 1

They speed up chemical reactions by acting as biological catalyst

Question 2

Enzymes are ……

Answer 2

Biological catalysts

Question 3

What is an example of enzymes being used at a cellular level

Answer 3

Respiration

Question 4

What is an example of enzymes being used for organisms as a whole

Answer 4

Digestion in mammals

Question 5

What do enzymes affect

Answer 5

Structures in an organism
Functions of an organism

Question 6

Enzyme action can be ….

Answer 6

Intracellular and extracellular

Question 7

What does intracellular mean

Answer 7

Within cells

Question 8

What does extracellular mean

Answer 8

Outside cells

Question 9

What is the toxic by product of many cellular reactions

Answer 9

Hydrogen Peroxide (H2O2)

Question 10

What happens if hydrogen peroxide is left to build up

Answer 10

It kills cells

Question 11

What is the enzyme responsible for the breakdown of H2O2

Answer 11

Catalase, hydrogen peroxide to harmless oxygen and water

Question 12

Give an example of an intracellular enzyme

Answer 12

Catalase

Question 13

Give an example of extracellular enzyme

Answer 13

Amylase and Trypsin

Question 14

Where does catalase work

Answer 14

Inside the cell (intracellular)

Question 15

Where does amylase and trypsin work

Answer 15

Outside cells (extracellular) in the digestive system

Question 16

Where is amylase found

Answer 16

Saliva (secreted to the mouth by salivary glands)

Question 17

What does amylase catalyse

Answer 17

The hydrolysis of starch to maltose (a sugar) in the mouth

Question 18

What does trypsin catalyse

Answer 18

The hydrolysis of peptide bonds - turns big polypeptides to smaller ones

Question 19

Where is trypsin produced

Answer 19

Cells in pancreas

Question 20

Where is trypsin secreted to

Answer 20

Small intestine

Question 21

What type of protein are enzymes

Answer 21

Globular protein

Question 22

Enzymes have…

Answer 22

An active site, which has a specific shape

Question 23

What is the active site

Answer 23

The part of the enzyme that the substrate molecules bind to

Question 24

How is the specific shape of the active site determined

Answer 24

By the enzymes tertiary structure

Question 25

What need to happen for the enzyme to work

Answer 25

Substrate has to fit into the active site.

Question 26

What happens if the substrate doesn’t match the active site

Answer 26

If the substrate doesn’t match the active site the reaction won’t be catalysed. Enzymes work few substrates - usually one.

Question 27

What is activation energy

Answer 27

A certain amount of energy that needs to be supplied to the chemicals before the reaction will start - often provided as heat.

Question 28

What do enzymes do to the activation energy

Answer 28

Reduces activation energy - speeds up rate of reaction

Question 29

What is formed when the substrate binds to an enzymes active site

Answer 29

Enzyme-substrate complex

Question 30

The formation of the enzyme substrate complex lowers ….

Answer 30

The activation energy

Question 31

Why does the formation of the enzyme-substrate complex lower the activation energy

Answer 31

-if two substrate molecules need to be joined, attaching to the enzyme holds them close together reducing any repulsion so they can bind easily
-if the enzyme is catalysing a breakdown reaction fitting into the active site puts a strain on bonds in the substrate. This strains means the substrate molecule breaks more easily

Question 32

Enzymes only work with

Answer 32

Substrates that fit their active site

Question 33

What did early scientists come up with to study action of enzymes

Answer 33

Lock and key theory

Question 34

What is the lock and key theory

Answer 34

This is where the substrate fits into the enzyme in the same way that a key fits into a lock

Question 35

Why did scientists realise that lock and key wasn’t totally perfect

Answer 35

New evidence showed that enzyme-substrate complex changed shape slightly to complete the fit.