Ch1 Proteins and Enzymes

Question 1

Amino acid groups

Answer 1

1. amine NH2
2. carboxyl COOH
3. hydrogen H
4. R group

Question 2

Globular protein

Answer 2

1. soluble
2. specific tertiary structure

Question 3

Fibrous protein

Answer 3

1. strong
2. insoluble
3. inflexible

Question 4

Primary structure

Answer 4

1. sequence of amino acids
2. condensation reaction between COOH and NH2
3. peptide bonds
4. polypeptide chain

Question 5

Secondary structure

Answer 5

1. primary structure coils to form helix
2. held by hydrogen bonds

Question 6

Tertiary structure

Answer 6

1. secondary structure folds to form specific 3D shape
2. ionic bonds
3. hydrogen bonds
4. disulfide bridges

Question 7

Quaternary structure

Answer 7

1. multiple polypeptide chains
2. associated with prosthetic groups

Question 8

Test for proteins

Answer 8

1. Add biuret reagents (sodium hydroxide then copper (II) sulfate)
2. blue to purple colour

Question 9

Structure of collagen

Answer 9

1. made of glycine
2. forms tight coil with little branching
3. coiled into secondary helix
4. 3 tertiary structures wrap around
5. fibrous protein used in tendons

Question 10

Enzymes

Answer 10

1. catalysts
2. speed up rate of reaction by lowering activation energy
3. recycled

Question 11

Enzyme structure

Answer 11

1. globular protein
2. specific active site shape
3. complementary to substrate
4. bind to form enzyme- substrate complex

Question 12

Induced fit model

Answer 12

1. active site changes shape
2. substrate binds to active site
3. active site moulds around substrate
4. forms enzyme-substrate complex

Question 13

Lock and key theory

Answer 13

1. active site is rigid
2. only complementary substrate binds
3. form enzyme-substrate complex

Question 14

Temperature on enzyme activity

Answer 14

1. kinetic energy increases
2. molecules move faster
3. increased chance of successful collisions
4. increased chance of ES complex
5. increase rate of reaction

Question 15

Too high temperature on enzyme activity

Answer 15

1. bonds in tertiary structure break
2. loses active site shape
3. substrate no longer complementary
4. can’t form EX complex
5. enzyme denatured

Question 16

pH on enzyme acitvity

Answer 16

1. bonds in tertiary structure break
2. alters charged on amino acids
3. loses active site shape
4. substrate no longer complementary
5. can’t form EX complex
6. enzyme denatured

Question 17

Why normal enzyme action plateauxs

Answer 17

1. little amount of substrate
2. products block
3. difficult for enzyme substrate molecules to form

Question 18

Affects of increased substrate concentration

Answer 18

1. increased chance of successful collisions
2. increased chance of forming an ES complex
3. increased rate of reaction
4. continues until all enzyme active sites are full

Question 19

Competitive inhibitor

Answer 19

1. similair shape to substrate
2. complementary shape to active site
3. blocks active site
4. prevents ES complexes from forming

Question 20

Non-competitive inhibitor

Answer 20

1. binds to another site on enzyme
2. enzyme shape changes- alters active site
3. no ES complexes can form

Question 21

Affect of enzyme concentration

Answer 21

1. it is limiting
2. if all active sites saturated, rate stays the same

Question 22

Activation energy

Answer 22

minimum amount of energy required for reaction to take place