2.3.8 - The Role Of Enzymes

Question 1

Describe Enzymes
(6 Points)

Answer 1

~ Biological catalysts, by speeding up chemical reactions without be used up or undergoing permanent change.

~ Speed up reactions by lowering the activation energy of reactions.

~ Are globular proteins with
complex tertiary structures, meaning they are highly specific and are produced via protein synthesis.

~ Control metabolic pathways.

~ Can be secreted inside or outside the cell and can work intracellularly and extracellularly.

~ Enzymes avoid the need for extreme conditions to occur, which will kill cells.

Question 2

What Is Meant By ‘Activation Energy’?
(2 Points)

Answer 2

~ For a reaction to proceed there must be enough activation energy.

~ The amount of energy needed by the substrate to become unstable enough for a reaction to occur and for products to be formed.

Question 3

Describe Enzymes Association With Activation Energy
(4 Points)

Answer 3

~ Enzymes lower the amount of activation energy needed, often by making reactions occur at lower temperatures, speeding up the rate of reaction.

~ When an substrate fits into the enzymes active site, an enzyme-substrate complex is formed.

~ Enzymes speed up chemical reactions because they reduce the stability of bonds in the reactants.

~ The destabilisation of bonds in the substrate makes it more reactive.

Question 4

How Does The Formation Of Enzyme Substrate Complexes Reduce The Activation Energy?
(2 Points)

Answer 4

~ If 2 substrate molecules need to be joined, being attached to the enzyme holds them close together, reducing and repulsion between the molecules so they can bond more easily.

~ If the enzyme is catalysing a breakdown reaction, fitting into the active site puts a strain on bonds in the substrate, so the substrate molecule breaks up more easily.