enzymes

Question 1

why are enzymes biological catalysts

Answer 1

lower the activation energy by bending its bonds

Question 2

Induced fit hypothesis

Answer 2

• substrate bind to complementary active site by slightly changing its shape to fit the active site
• forms an enzyme substrate complex

Question 3

what happens to rate of reaction when temperature increased?

Answer 3

• at lower temps starts off slow due to not having much kinetic energy
• as temperature increases, rate of reaction increases as there is more kinetic energy so ESC’s form faster
• past the optimum, rate decreases due to denaturing of enzymes, this means the bonds within the enzymes 3D tertiary structure change causing the active site to no longer be complementary to the substrate
• escs don’t form

Question 4

explain shape of substrate concentration graph (increases and levels off)

Answer 4

• rate of reaction increases as substrate concentration increases as more substrates are available to bind to free active sites, increasing number of ESC’s
• levels off due to substrate concentration no longer being the rate limiting factor, instead the enzyme concentration becomes the rate limiting factor due to substrate being in excess and the rate being limited to the number of active sites
• maximum number of ESC’s form, causing the rate to stay the same

Question 5

enzyme concentration and rate of reaction graph

Answer 5

• rate increases as at the start, enzyme conc is the rate limiting factor
• more enzyme active sites are available for substrates to bind to, forming more ESC’s
• enzyme concentration is no longer rate limiting factor, they are now in excess however substrate concentration becomes rate limiting factor causing rate of reaction to stay the same

Question 6

competitive inhibitor

Answer 6

• inhibitor similar shape to substrate, therefore can bind to the enzymes active site
• if inhibitor binds, substrate prevented from binding and reaction doesn’t occur
• increasing substrate concentration decreases its effectiveness

Question 7

Non-competitive inhibitor

Answer 7

• inhibitor binds to the allosteric site of the enzyme
• this causes the enzymes active to denature due to changing bonds within its tertiary structure
• not affected by substrate conc

Question 8

Inhibitor graphs

Answer 8

• competitive = increases but at slower rate than original due to inhibitors binding the enzymes active site, preventing substrates from binding and the reactions occurring. levels off at same rate as original as high substrate concentration decreases the effectiveness of the inhibitor, rate returns to normal
• non- competitive = much slower and levels off quickly due to not being affected by substrate concentration, all enzymes become denatured preventing ESC’s from forming