Enzymes and Coenzymes

Question 1

What is an enzyme

Answer 1

Usually a protein (most are gobular proteins) acting as a catalyst (lowers activation energy) in a specific biochemical reaction

Question 2

Every reaction in a cell requires

Answer 2

its own specify enzyme

Question 3

Simple enzymes structure

Answer 3

composed of only a protein

Question 4

Conjugated enzyme structure

Answer 4

Composed of

Apoenzyme - protein part
Coenzyme - non-protein part

Question 5

Role of an enzyme

Answer 5

To facilitate a specific chemical reaction

Question 6

Structure of an Amino acid

Answer 6

Organic compound with both

NH2 (amino group) and -COOH (carboxyl group) functional groups

Question 7

What is a Coenzyme

Answer 7

A small organic molecule, acting as a cofactor in a conjugated enzyme

Derived from vitamins - many vitamins act as coenzymes such as B-vitamins

Question 8

Holoenzyme

Answer 8

the combination of the apoenzye and coenzyme which together facilitate a chemical reaction

Question 9

What do all enzymes end with (suffix) and some examples

Answer 9

‘ase’

Lactase = breakdown of milk 
Amaylase =  breaks down starch 
Protase = brakes down dietary proteins

Question 10

Digestive enzymes end in the suffix

Answer 10

-in

Pepsin, trypsin, chymotrypsin

Question 11

energy required for a reaction to occur

Answer 11

activation energy

Question 12

Enzyme-substrate complex is

Answer 12

the temporary intermediate complex between an enzyme and its substrate

Substrate binds to active site an enzyme substrate complex is formed temporarily

Question 13

What is enzyme activity

and what are the 4 factors that affect enzyme activity

Answer 13

the measure of the rate at which an enzyme converts substrate to product

Temp
PH
Substrate concentration
Enzyme concentration

Question 14

What happens in the course of an enzyme catalysed chemical reaction? Refer to the enzyme, substrate, active site, enzyme-substrate complex and product in your answer.

Answer 14

An enzyme will bind to a substrates active site where an enzyme-substrate complex is temporarily formed. This allows the substrate to undergo a chemical reaction producing a product.

Question 15

Why is it that each different chemical reaction requires a different enzyme?

Answer 15

Only specific substrates and specific enzymes fit together due to the shape of the active site. Therefore a different enzyme is required to catalyse (lower activation energy) a reaction.

Question 16

Explain the induced fit model of enzyme action

Answer 16

the enzyme slightly changes the shape of its active site to accommodate the binding of a specific substrate in order to begin the chemical reaction.

Question 17

Explain the lock and key model of enzyme action

Answer 17

The active site is fixed and rigid (lock) and the substrate (key) must fit exactly into the rigid enzyme

Question 18

What is an enzyme inhibitor

Answer 18

A substance that slows down or stops the normal function of an enzyme by binding to the enzyme ( therefore no active site will be available for substrate)

Question 19

what are the 3 types of inhibition and their function

Answer 19

reversible competitive inhibition = Binds to enzymes active site without changing the shape of the active site ( it is complementary to the enzymes active site- perfect fit). This prevents the substrate from binding to the enzyme thus blocking reaction.

Reversible non-competitive inhibition = Binds to another site on the enzyme other than the active site altering the shape of the active site. This decreases enzyme activity as substrate cannot fit into the active site.

Irreversible inhibition = binds to active site and permanently deactivates enzyme. Does not resemble substrate.

Question 20

Zymogens are

Answer 20

enzymes that are synthesised in the inactive form