Enzymes - Introduction

Question 1

What are the two shapes of protein?

Answer 1

Fibrous and Globular

Question 2

Describe Fibrous Proteins

Also known as structural proteins

Answer 2

• Linear in shape
• Tough
• Insoluble in water

Question 3

Describe Globular Proteins

Answer 3

• Spherical (roughly) shape
• Soluble in water
• Generally take part in chemical reactions and interactions

Question 4

All enzymes are?

Answer 4

Proteins

Question 5

What type of proteins are enzymes?

Answer 5

Globular

Question 6

What is the general purpose of enzymes?

Answer 6

To speed up chemical reactions and act as catalysts

Question 7

What are the two catgeories of enzymes?

Answer 7

• Monomeric enzymes
• Oligomeric enzymes

Question 8

What are monomeric enzymes?

Answer 8

Enzymes made of 1 polypeptide chain

Question 9

What are oligomeric enzymes?

Answer 9

Enzymes made of two or more polypeptide chains

Most enzymes are oligomeric

Question 10

What are the two types of Models to explain enzyme action?

Answer 10

* Lock and Key
* Induced Fit

Question 11

What is the name of the substance that works with an enzyme?

Answer 11

Substrate

Question 12

What is the name of the part of the enzyme that binds to the substrate?

Answer 12

Active Site

Question 13

What is the name given when enzyme and substrate are bound to each other?

Answer 13

Enzyme-substrate complex

Question 14

Describe how Enzyme-substrate complexes form

Answer 14

• Substrate forms weak bonds with particular amino acids in active site
• Bonda are temporary and only exist until product is formed

Question 15

Why can a small amount of enzymes produce a large amount of product?

Answer 15

Enzymes can be re-used. They are not used up in reaction.

Question 16

Explain Lock and Key Model

Answer 16

• Enzymes are specific and will only catalyse one type of reaction
• Both enzymes and substrate have a fixed - rigid -shape
• Enzyme’s complementary shape binds to substrate and forms an enzyme-substrate complex
• Enzymes catalyses reaction and chemically changes substrate into product
• Enzyme is reused

Question 17

How is the Induced Fit Model different to the Lock and Key Model?

Answer 17

• The general process is the same
• Shape of enzymes have some flexibility
• Active Site of enzyme changes to become complementary to substrate
• Active site returns to original shape after catalysis of substrate is completed

Question 18

Which model - induced fit or lock and key model - is more correct/modern?

Answer 18

Induced fit - it has predominantly replaced lock and key model

Question 19

There are 3 types of enzyme specificity (what an ezyme is specific to). State the 3:

Answer 19

1. Absolute / Substrate specificity
2. Bond specificity
3. Group specificity

Question 20

Describe Absolute / substrate specificity

Answer 20

Specific to particular substrate. Will only catalyse a particular molecule/substrate.

Eg: Lactase is only specific to lactose and will catalyse its break down

Question 21

Describe Bond Specificity

Answer 21

Specific to a particular chemical bond.

Eg: Peptidase is only specific to peptide bonds and will catalyse them

Question 22

Describe Group Specificity

Answer 22

Specific to a particular functional group thats part of a substrate

Eg: Specific to carboxyl or amino group on substrate