3.2.1 Regulation of biochemical pathways

Question 1

enzyme

Answer 1

biological catalyst (protein) that speeds up reaction by lowering activation energy needed for a reaction to proceed (and is not used up)

Question 2

active site

Answer 2

unique 3d shape/region of an enzyme that has complementary shape to its specific substrate allowing it to bind

Question 3

substrate

Answer 3

molecule enzyme binds to and acts on

Question 4

activation energy

Answer 4

initial energy required by substrates in order for reaction to proceed

Question 5

induced fit model

Answer 5

enzyme’s active stie slightly changes upon binding with substrate to become complementary to substrate

Question 6

catabolic

Answer 6

complex substrate being pulled apart to form simple products
(exergonic release energy)

Question 7

anabolic

Answer 7

two or more simple substrates joined together to form complex product (endergonic require energy)

Question 8

denaturing

Answer 8

bonds holding protein’s unique 3D structure (tertiary) are broken changing the shape of an active site so it is no longer complementary to its substrate and cannot bind with it
- irreversible

Question 9

temperature

Answer 9

• increasing speeds up molecules so enzymes collide with substrates more often
• increasing above optimal denatures
• decreasing slows down enzyme activity

Question 10

ph

Answer 10

• increasing or decreasing above or below

Question 11

substrate concentration

Answer 11

• increased concentration of substrate means enzymes collide with substrates and bind more often
• at saturation point all enzyme active sites are occupied and cannot catalyse reactions any faster

Question 12

enzyme concentration

Answer 12

• increases, enzymes collide with substrates more often and bind, unlimited substrate means reaction will continue to increase

Question 13

inhibitor

Answer 13

molecule binds with enzyme to decrease enzyme activity

Question 14

irreversible

Answer 14

permanently binds with enzyme inactivating/blocking its active site

Question 15

reversible

Answer 15

temporarily binds with enzyme so active site is available less often

Question 16

competitive

Answer 16

• complementary to enzyme’s active site, binds with enzyme’s active site blocking substrate from binding with the active site of enzyme
• effect can be overcome by increasing substrate

Question 17

non competitve

Answer 17

binds with region other than active site and alters shape of active site so it is no longer complementary with substrate and substrate cannot bind

Question 18

end product inhibition

Answer 18

• product of enzymatic pathway binds to and inhibits action of an enzyme earlier in the pathway to prevent formation of enzyme-substrate complex
• as product level increases, decreases rate of reactions that produce product allowing for maintenance of relatively stable product levels
• conserving cellular energy and resources

Question 19

coenzyme

Answer 19

• organic non-protein molecule that binds temporarily to enzyme increasing its ability to bind with substrate
• can be carrier molecules donating molecules or energy

Question 20

ATP as a coenzyme

Answer 20

• once energy released, phosphate group detaches so ATP becomes ADP
• ADP gets phosphate readded to become ATP and catalyse more reactions