1.4.2 Enzymes

Question 1

Define the role of an enzyme

Answer 1

Increase the rate of reaction, by lowering the activation energy but are not used up in the process itslef

Question 2

Can enzymes be used for any reaction

Answer 2

• Enzymes are reaction-specific
• Shape is complimentary to substrates

Question 3

How does an enzyme increase the rate of reaction

Answer 3

By lowering the activation energy

Question 4

What is the protein strucutre of an enzyme

Answer 4

• Tertiary
• Globular
• 3D

Question 5

What does the substrate bind to on an enzyme

Answer 5

The active site

Question 6

Describe and explain the induced-fit model of enzymes

Answer 6

• Substrate collides and binds to active site
• Enzyme’s shape and active site changes slightly as bonds bend
• Enzyme substrate complex has formed
• Active site becomes complimentary in shape to substrate
• Strains are put on the bonds in the substrate
• Activation energy lowered
• Product released

Question 7

Describe how increasing the temperture affects an enzyme-controlled reaction, until the point of optinum temperature

Answer 7

• Increasing temperature increases rate of reaction
• Kinetic energy increases
• More successful enzyme-substrate collisons
• More enzyme-substrate complexes formed

Question 8

Describe how increasing the temperture affects an enzyme-controlled reaction, after the point of optinum temperature

Answer 8

• Above optinum temperature, rate decreases
• Hydrogen bonds broken
• Change in tertiary structure and therefore shape
• Shape of active site no longer complimentary to substrate
• Enzyme has become denatured

Question 9

Describe how altering the pH affects the rate of an enzyme-controlled reaction

Answer 9

• Change in pH away from optinum causes rate to decrease
• Ionic and hydrogen bonds broken
• Change in tertiary structure and therefore shape
• Shape of active site no longer complimentary to substrate
• Enzyme becomes denatured
• No enzyme-substrate complexes can form

Question 10

Describe how increasing the substrate concentration affects the rate of an enzyme-controlled reaction

Answer 10

• Increases rate
• More sucsessful enzyme-substrate collisions
• More enzyme-substrate complexes formed
• Maximum rate when all active sites occupied

Question 11

Describe how increasing the enzyme concentration affects the rate of an enzyme controlled reaction

Answer 11

• Increases rate
• More successful enzyme substrate collisions
• More enzyme-substrate complexes formed
• Maximum rate when all substrates bonded to active sites

Question 12

Describe competitive inhibitors

Answer 12

• Similar shape to active site
• Binds to active site, blocking it
• Substrate cannot bind
• No ezyme-substrate complexes formed
• Effects reduced by increasing substrate concentration

Question 13

Describe non-cometitive inhibitation

Answer 13

• Binds to allosteric site (not active site)
• Causes change in tertiary structure and therefore shape of enzyme
• Change in shape of active site
• Active site no longer complimentary to shape of substrate
• Substrate cannot bind
• No enzyme-substrate complexes formed
• Effects NOT reduced by increasing substrate concentration