C1.1 Enzymes & Metabolism

Question 1

What do catalysts do?

Answer 1

Catalysts speed up the rate of chemical rxs without themselves getting changed

Question 2

What are enzymes

Answer 2

Enzymes are protein-based catalysts

Question 3

What is the process of chemical rxs?

Answer 3

reactants-> products

Question 4

What is the process of enzyme catalysed rxs?

Answer 4

substrates->products

Question 5

What is metabolism?

Answer 5

Metabolism is all enzyme-catalysed reactions in a cell

Question 6

Where are enzymes always needed?

Answer 6

Enzymes are always needed in metabolic rxs

Question 7

What are the types of metabolic rxs?

Answer 7

Catabolic & Anabolic

Question 8

Anabolic rxs….

Answer 8

-Small to big
-Build up
-Condensation
-Require energy

Question 9

Catabolic rxs….

Answer 9

-Big to small
-Breakdown
-Hydrolysis
-Release energy

Question 10

What are the properties of enzymes

Answer 10

-Soluble
-3D
-Globular proteins

Question 11

What is substrate-specificity?

Answer 11

Substrate-specificity is the shape and chemical properties of an enzyme allowing a substrates to bind but not other substances

Question 12

What is induced fit binding?

Answer 12

Induced fit binding is when the interactions between substrates and enzymes cause active site to change in shape. These changes make it easier for bonds within substrates to break and form new bonds (catalyzed rxs)

Question 13

What are the steps of induced fit binding?

Answer 13

1. Substrate binds to enzyme
2. Active site changes shape
3. Changes in active site allow for catalyzed rxs to occur
4. Product is released
5. Active site goes back to original shape

Question 14

What needs to happen in order for chemical rxs to take place?

Answer 14

Collision between substrates and enzymes need to occur in order for chemical rxs to take place

Question 15

What are the different types of molecular collisions?

Answer 15

substrate->enzyme
enzyme->substrate
enzyme-><-substrate

Question 16

What is denaturation?

Answer 16

Denaturation is when interactions between amino acids within the protein cause changes to the active site, making it no longer work as a catalyst

Question 17

What factors affect enzyme activity?

Answer 17

-Temperature
-Ph
-Substrate concentration

Question 18

Effects of temperature on enzyme activity….

Answer 18

-As temperature is increased, molecular motion also increases
-This causes increased frequency of collision
-Increases the rate of reaction
-Until an optimum is reached
-Enzyme gets denaturation if temp gets increased more

Question 19

Effects of Ph on substrate activity….

Answer 19

If Ph changes past the optimum of enzyme, the shape of the active site is altered and substrates can no longer bind to them

Question 20

Effects of substrate concentration on enzyme activity….

Answer 20

If the concentration of a substrate is increased, substrate-active site collisions will also increase. The rate at which enzymes catalyse get smaller and smaller since more active sites are getting blocked

Question 21

What is activation energy?

Answer 21

Activation energy is the energy required for a chemical rxn to start

Question 22

How do enzymes speed up chemical rxs?

Answer 22

Enzymes speed up chemical rxs by reducing the activation energy

Question 23

What are extracellular enzymes?

Answer 23

-Extracellular enzymes are enzymes that are used outside of the cell
-Extracellular enzymes are produced by ribosomes in the rough ER
-Extracellular enzymes travel from the rough ER to the Golgi Apparatus by vesicles and outside of the cell

Question 24

What are intraacellular enzymes?

Answer 24

-Intracellular enzymes are enzymes that are used within the cell
-Intracellular enzymes are products by free flowing ribosomes in the cytoplasm

Question 25

What do metabolic rxs produce & why?

Answer 25

Energy transfer is not 100% efficient and therefore energy is lost as heat

Question 26

What are the 2 types of metabolic rxs?

Answer 26

-Cyclical, like the Krebs cycle
-Linear, like photolysis

Question 27

Outline one feature of a metabolic cycle that distinguishes it from a chain?

Answer 27

Products become substrates

Question 28

What is non-competitive inhibition?

Answer 28

Non-competitive inhibition is when a substance binds to the allosteric site of an enzyme changing the shape of the active site preventing substrates from binding

Question 29

What is competitive inhibition?

Answer 29

Competitive inhibition is when a substance with similar shape to the substrate binds to the active site of an enzyme blocking substances from binding

Question 30

Characteristics of non-competitive inhibition….

Answer 30

-Interacts with r-chains of amino acids at surface of enzyme
-Speeds up enzyme activity
-Inhibitor does not have similar shape to the substarte
-Inhibitor binds to the allosteric site
-Inhibitor does not bind to the active site
-Inhibition is usually permanent
-Inhibition cannot be reduced by adding substrate concentration

Question 31

Characteristics of competitive-inhibition….

Answer 31

-Interacts with r-chains of amino acids at surface of enzyme
-Speeds up enzyme activity
-Inhibitor has similar shape to substrate
-Inhibitor binds to active site
-Inhibitor does not bind to allosteric site
-Inhibition can be reversed
-Inhibition can be reversed by adding substrate concentration

Question 32

Draw how competitive & non-competitive inhibition influence rxn rates….

Answer 32

….

Question 33

What happens in feedback (end-product) inhibition?

Answer 33

In feedback/end product inhibition the end product of a metabolic pathway becomes a non-competitive inhibitor to the first enzyme in the chain

Question 34

How does the metabolic pathway start working again after feedback/end product inhibition?

Answer 34

The metabolic pathway starts working again when the end product concentration drops, causing the inhibitor to detach

Question 35

How does mechanism-based inhibition work?

Answer 35

In mechanism.based inhibition the non-competitive inhibitor binds to an enzyme anywhere in the chain permanently