Chapter 3: enzymes

Question 1

define ‘enzyme’

Answer 1

a globular protein that catalyses metabolic reactions

Question 2

name the two hypothesises relating to enyzmes

Answer 2

‘lock and key’ and ‘induced fit’ hypothesises

Question 3

describe the work of inhibitor molecules during competitive inhibition

Answer 3

• if an inhibitor molecules bind only briefly to the site, there is competition between it and the substrate for the site
• if there is much more of the substrate present than the inhibitor, substrate molecules can easily bind to the avtive site
• if the concentration of the inhibitor rises, the substrate is less likely to collide with an empty site

Question 4

describe the work of inhibitor molecules during non-competitive inhibition

Answer 4

• the molecule can bind to another part of the enzyme rather than the active site
• it can distupt the normal arrangement of hydrogen bonds and hydrophobic interactions holding the enzyme molecule in its three-dimensional shape
• the active site is distorted