3.1.4- Proteins

Question 1

impact of non-competitive inhibitors on enzyme action (2)

Answer 1

1. Binds to another area on enzyme molecule causing a change in AS shape, so the substrate cannot bind
2. Can be irreversible

Question 2

impact of competitive inhibitors on enzyme action

Answer 2

1) Same shape as substrate
2) Bind to AS directly, blocking access for E-S complex formation
3) can be overcome if add more substrate to out-compete inhibitor

Question 3

impact of enzyme conc on enzyme action

Answer 3

• If few, then E AS will become saturated and unable to work faster
• If many then more E-S can form
• Beyond certain point all substrates in E-S complexes and rate plateaus

Question 4

impact of substrate conc on enzyme action-

Answer 4

• if few> reaction slower as fewer collisions between E & S
• If many> reaction faster as more collisions between E&S
• Beyond certain level all enzymes saturated, then ROR plateaus

Question 5

impact of pH on enzyme action (2)

Answer 5

• If too high/ low- will interfere with charges in AA in AS of enzyme; this can break bonds holding TS in place and AS changes shape
• Thus enzymes denature & cannot form E-S complexes

Question 6

Impact of temp of e action= (3)

Answer 6

• If LOW, not enough ek for successful collisions between E & S, so SLOWER ROR
• If INCREASED, more ek for successful collisions between E&S so FASTER ROR
• If TOO high, enzymes denature, AS chanegs shape and E-S complexes cannot form

Question 7

Factors affecting rate of enzyme action (5)

Answer 7

• Temp
• pH
• Competitive & non-competitive inhibitors
• enzyme conc
• substrate conc

Question 8

Quaternary structure

Answer 8

when multiple 3D polypeptides form one protein

Question 9

Tertiary structure

Answer 9

• Further folding to form unique 3D shape (caused by interactions between R groups)
• Held together by ionic bonds/ H bonds/ disulphide bridges

Question 10

Secondary structure= (2)

Answer 10

• H bonds form between AA at other section on chain

- Primary PP chain FOLDS> beta-pleated sheet or BENDS into a-helix

Question 11

Primary structure=

Answer 11

• order of AA in polypeptide

- Joined by peptide bonds

Question 12

Structure of amino acid= (3)

Answer 12

1) Amino group (NH2)
2) Carboxyl group (COOH)
3) Variable group (R)

Question 13

Induced fit model

Answer 13

1) when enzyme’s active site is induced, it slightly changes shape to mould around the substrate
2) this movement puts stain on bonds, therefore less energy needed to break bonds (lowering AE)

Question 14

impact of competitive inhibitors on enzyme action

Answer 14

1) Same shape as substrate
2) Bind to AS directly, blocking access for E-S complex formation
3) can be overcome if add more substrate to out-compete inhibitor