C1.1 Enzymes & Metabolism Flashcards
What do catalysts do?
Catalysts speed up the rate of chemical rxs without themselves getting changed
What are enzymes
Enzymes are protein-based catalysts
What is the process of chemical rxs?
reactants-> products
What is the process of enzyme catalysed rxs?
substrates->products
What is metabolism?
Metabolism is all enzyme-catalysed reactions in a cell
Where are enzymes always needed?
Enzymes are always needed in metabolic rxs
What are the types of metabolic rxs?
Catabolic & Anabolic
Anabolic rxs….
-Small to big
-Build up
-Condensation
-Require energy
Catabolic rxs….
-Big to small
-Breakdown
-Hydrolysis
-Release energy
What are the properties of enzymes
-Soluble
-3D
-Globular proteins
What is substrate-specificity?
Substrate-specificity is the shape and chemical properties of an enzyme allowing a substrates to bind but not other substances
What is induced fit binding?
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)
What are the steps of induced fit binding?
- Substrate binds to enzyme
- Active site changes shape
- Changes in active site allow for catalyzed rxs to occur
- Product is released
- Active site goes back to original shape
What needs to happen in order for chemical rxs to take place?
Collision between substrates and enzymes need to occur in order for chemical rxs to take place
What are the different types of molecular collisions?
substrate->enzyme
enzyme->substrate
enzyme-><-substrate
What is denaturation?
Denaturation is when interactions between amino acids within the protein cause changes to the active site, making it no longer work as a catalyst
What factors affect enzyme activity?
-Temperature
-Ph
-Substrate concentration
Effects of temperature on enzyme activity….
-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
Effects of Ph on substrate activity….
If Ph changes past the optimum of enzyme, the shape of the active site is altered and substrates can no longer bind to them
Effects of substrate concentration on enzyme activity….
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
What is activation energy?
Activation energy is the energy required for a chemical rxn to start
How do enzymes speed up chemical rxs?
Enzymes speed up chemical rxs by reducing the activation energy
What are extracellular enzymes?
-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
What are intraacellular enzymes?
-Intracellular enzymes are enzymes that are used within the cell
-Intracellular enzymes are products by free flowing ribosomes in the cytoplasm
What do metabolic rxs produce & why?
Energy transfer is not 100% efficient and therefore energy is lost as heat
What are the 2 types of metabolic rxs?
-Cyclical, like the Krebs cycle
-Linear, like photolysis
Outline one feature of a metabolic cycle that distinguishes it from a chain?
Products become substrates
What is non-competitive inhibition?
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
What is competitive inhibition?
Competitive inhibition is when a substance with similar shape to the substrate binds to the active site of an enzyme blocking substances from binding
Characteristics of non-competitive inhibition….
-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
Characteristics of competitive-inhibition….
-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
Draw how competitive & non-competitive inhibition influence rxn rates….
….
What happens in feedback (end-product) inhibition?
In feedback/end product inhibition the end product of a metabolic pathway becomes a non-competitive inhibitor to the first enzyme in the chain
How does the metabolic pathway start working again after feedback/end product inhibition?
The metabolic pathway starts working again when the end product concentration drops, causing the inhibitor to detach
How does mechanism-based inhibition work?
In mechanism.based inhibition the non-competitive inhibitor binds to an enzyme anywhere in the chain permanently
