Lab 4: Enzymes

Question 1

define: enzymes and state their importance

Answer 1

• proteins that increase the rate of chemical reactions by acting as catalysts that lower the activation energy of the reaction.
• essential because most metabolic reactions would not take place unless catalysed by enzymes

Question 2

When a scientists wants to share their discoveries with others, they write articles for scientific journals. These articles generally have 5 key sections. State them

Answer 2

• introduction
• materials
• methods
• results
• discussion

Question 3

The reaction rate of the digestion of starch by alpha amylase is low at 0 degrees. Why? Make sure to use the following words in your discussion: kinetic energy, collisions, complexes

Answer 3

At low temperatures, enzymes and substrates have low kinetic energy meaning the frequency of collisions and the formation of enzyme substrate complexes is very low. The reaction thus proceeds at a much lower rate than if it were at a higher temperature.

Question 4

The reaction rate of the digestion of starch by alpha amylase suddenly drops between 37 degrees and 60 degrees. Propose some possible explanations for this result.

Answer 4

37-60 can be called the ideal range of temperatures for the starch amylase. The temperature at which the enzyme can most efficiently speed up the digestion of starch.

Question 5

define: competitive inhibition

Answer 5

• when a specific inhibitor molecule binds reversibly to the active site of an enzyme; the inhibitor slows down the reaction rate of the substrate by competing with the substrate for the enzyme’s active site. the rate of reaction depends primarily on the concentration fo substrate relative to competitive inhibitor

Question 6

define: non competitive inhibitor

Answer 6

• inhibitor that binds to allosteric site (any site but the active site) of enzyme and changes the shape of the active site or otherwise prevents the substrate from binding to the active site. The enzyme is changed and no longer functions normally.

Question 7

Why is reaction rate so low at extremely high and low pHs?

Answer 7

At extreme pH values most proteins denature. Their shape changes and as a result they are unable to bind to substrates efficiently if at all. If they are unable to create complexes with substrates, reactions will not take place.