Enzymes

Question 1

Enzyme graph

Answer 1

1- initially lots of substrate and empty active sites
Many E-S complexes can form speeds up reaction
Reaction starts of fast
2- less substrate and more product
So it’s more difficult for E-S complexes to form
Reactions slows down
3- no more substrate
So no more E-S complexes
Reaction stops

Question 2

Rate of reaction formula

Answer 2

Volume/time=rate of reaction

Question 3

Effect of temperature graph (volume of product)

Answer 3

• Enzymes have more kinetic energy at 37°
• so more E-S complexes
• faster reaction
• converse

Question 4

Effect of temperature (rate of reaction)

Answer 4

• as temperature ^ the rate ^ due to more Ek
• optimum temperature = most E-S complexes form
•temp ^ rate ⬇️ as enzymes are denatured
• tertiary structure changed so no E-S complexes can form

Question 5

Effect of pH (volume of produced)

Answer 5

• ^ as H+ ions are attracted to the amino acids of enzymes
• ionic and hydrogen bonds in the tertiary structure are disrupted
• active sites of enzymes denature
• fewer E-S complexes form
• reaction incomplete
• for pH 7 it’s converse

Question 6

Effect of pH (rate of reaction)

Answer 6

• active site denatures so no E-S complexes form
• optimum pH
• Active site denatures which means no E-S complexes form

Question 7

Effect of enzyme concentration (volume of product)

Answer 7

2 moles catalase:
• faster reaction
• ^ enzymes = ^ E-S complexes
• accept converse

Question 8

Effect of enzyme concentration (rate of reaction)

Answer 8

• enzyme conc^ rate of reaction ^
• in direct proportion
• as more E-S complexes form
• rate is only limited by amount of substrate
More active sites= more fast reactions

Question 9

Effect of substrate concentration (volume of product)

Answer 9

2 moles substrate:
• faster reaction
• ^ substrate ^ E-S Complexes
• Accept converse

Question 10

Effect of substrate concentration (rate of reaction)

Answer 10

• as substrate conc ^ rate ^
• directly proportional
• more E-S complexes are formed
• rate is only limited by amount of enzyme

Question 11

What are enzyme inhibitors?

Answer 11

They slow down catalysed reactions

Question 12

What are competitive inhibitors?

Answer 12

Molecules with a similar shape to a substrate. They act as active sites and prevent E-S complexes from forming

Question 13

Competitive inhibitors (volume of product)

Answer 13

Slows reaction
C.I binds to active site
Prevents E-S complexes

Question 14

Competitive inhibitors (rate of reaction)

Answer 14

You can increase the rate of product formation by adding more substrate

The additional substrate will outcompete the inhibitor

Question 15

What are non-competitive inhibitors?

Answer 15

•Molecule that attach to the allosteric binding site (not active site) on an enzyme
•This changes the tertiary structure of the active site permanently
•active site is no longer complementary
•No E-S complexes can form

Question 16

Non-competitive inhibitor (rate of reaction)

Answer 16

• you can’t increase the rate of product formation by adding more substrate
• the enzyme are out of action. Add more enzymes to overcome this

Question 17

Non-competitive inhibitor (volume of product)

Answer 17

• reaction slows and doesn’t complete
• NCI binds to allosteric binding site
• active site changes shape
• no E-S complexes can form

Question 18

What is the primary structure of protein?

Answer 18

The sequence of amino acids which is determined by genes

Question 19

What is the secondary structure of proteins?

Answer 19

Hydrogen bonds form between the amino acids in the chains. This makes it either an alpha helix or a beta pleated sheet.

Question 20

What is the tertiary structure of protein?

Answer 20

The folded chain of amino acids are further folded. Hydrogen and ionic bonds form between different parts of the polypeptide chain. This folding forms the polypeptide into a 3D shape.

Question 21

What is the quaternary structure of protein?

Answer 21

Multiple polypeptides bonded e.g) haemoglobin

Question 22

What is activation energy ?

Answer 22

The minimum amount of energy that is required for molecules to collide with each other

Question 23

What does high kinetic energy do in a catabolic reaction ?

Answer 23

Strains the bonds so the substrate molecules breaks more easily

Question 24

Anabolic reactions

Answer 24

Brings substrates closer together. Lowers the activation energy needed for the reaction to take place reducing repulsion between molecule so they bond more easily.

Question 25

Structural proteins

Answer 25

Structural proteins are physically strong. They consist of king polypeptide chains lying parallel to each other with cross links between them. Eg) Keratin
Collagen has three polypeptide chains which makes it strong. This is a great supportive tissue in animals.