Biology Core Principles 1.4 - Enzymes

Developed from the resources provided by Peter Symonds College

There are lots of flashcards, just to ensure that everything is covered for any eventuality in the exams

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What is Metabolism?
A combination of anabolic and catabolic reactions, catalysed by Enzymes
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What are Enzymes?
They are Proteins in their tertiary structure; they are a type of Metabolic (Globular) Protein; they can speed up reactions without being used up
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What is special about the Active Site?
It is complementary in shape to the substrate that it is designed to split; the Enzyme as a whole is a specific shape
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Enzyme + Substrate = ?
Product (+ Enzyme)
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What four factors are Enzymes affected by?
Temperature, pH, Enzyme/Substrate Concentrations, Inhibitors (Competitive/Non-Competitive)
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What is the Enzyme and the Product of the Substrate: Maltose?
Maltase; 2 x α Glucose
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What is the Enzyme and the Product of the Substrate: Lipids?
Lipase; 3 x Fatty Acid + Glycerol
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What is the Enzyme and the Product of the Substrate: Proteins?
Protease; Amino Acids
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What is the Enzyme and the Product of the Substrate: Sucrose?
Sucrase; α Glucose + Fructose
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What is the Enzyme and the Product of the Substrate: Hydrogen Peroxide?
Catalase; Water + Oxygen
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What are the two theories for Enzyme reactions?
Lock & Key; Induced Fit
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What is the Lock & Key theory?
Specific shape active sire forms an Enzyme-Substrate Complex: the Substrate enters the Enzyme, the ESC forms, and the products are then released from the Substrate
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What is the Induced Fit theory?
The Substrate enters the Active Site, and pressure is applied as the Enzyme-Substrate Complex is formed around the Substrate - this aids in the hydrolysis of a bond; the Enzyme is then forced back to original shape (Substrate no longer same shape)
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What are the reactions that can form larger molecules or create smaller ones?
Condensation (larger molecules) and Hydrolysis (smaller molecules); Lysozyme Enzyme can be used to break down bacteria, but is found in tears and saliva
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What is Activation Energy?
Extra energy that is required to enable a reaction to occur; this energy is often supplied through heat in a laboratory reaction
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What effect do Enzymes have in Activation Energy?
They lower the energy required for a reaction to occur; allows a reaction to proceed quickly at lower temperatures
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What is the Turnover Number?
The number of products (converted molecules of substrate) per unit of time (i.e. Catalase has a turnover number of 200,000units/second/subunit)
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Is the optimal temperature for every Enzyme 37°C?
No, some Enzymes have different optimal temperatures, but it is commonly 37°C in mammals
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What is pH?
A measure of Hydrogen Ion (H+) concentration; the higher the concentration of H+ ions, the lower the pH
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What is the equation to find the rate of reaction?
1/time
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In a Concentration of Product - Time graph, what is the limiting factor when the graph levels off?
Substrate Concentration (all Substrate has been converted into the product)
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In a Concentration of Substrate - Time graph, what is the limiting factor when the graph levels off at 0?
Substrate Concentration (all Substrate has been converted into the product)
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What does the graph of the Concentration of Product - Temperature look like in comparison to the graph of Concentration of Substrate - Temperature?
The first graph looks like an "n", whereas the other graph looks like a "u"
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What is a pH buffer?
A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is added to it
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What happens if the pH is not at the optimum?
It will be inactive if it is within a certain range of the optimum, but will denature if it goes outside of the inactive range
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What happens when an Enzyme denatures?
The bonds (Hydrogen, Ionic, Disulphide, and Hydrophillic Interactions) begin to break, breaking the Tertiary Globular Structure. Shape of the Active Site will change, meaning the substrate is no longer complementary, less collisions occur
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Optimal pH: What happens when the charges in the Active Site match those on the Substrate?
Successful collisions will occur (no repulsion). At the optimum pH, it will take the shortest time to product the product as there are the greatest number of Enzyme Substrate Complexes forming
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Inactivation: What happens when there is an increase in hydrogen/hydroxide ions in the solution?
Charges in the Active Site may not be complementary to the Substrate, less ESCs will form due to less collisions - Enzyme said to be "inactive", but can be reversed with the addition of a pH Buffer
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What is common between a Substrate and a Competitive Inhibitor?
They have a similar shape, meaning they can enter the Active Site and block it, reducing the ESC-potential (it will not stop the reaction, but it will take longer to "finish" the reaction in full)
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What does a Non-Competitive Inhibitor do to an Enzyme?
It attaches away from the Active Site and distorts the shape, meaning it is no longer complementary in shape with the Substrate. This then limits the Rate of Reaction to a low figure, and the reaction will never "finish"
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What are Reversible Inhibitors?
They do not permanently bind with the Enzyme, meaning that they are not permanent and are therefore reversible
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What are Non-Reversible Inhibitors?
They permanently bind to the Enzyme in some way, and do not leave - therefore, it is Non-Reversible
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What is an Immobilised Enzyme?
An Immobilised Enzyme is an enzyme attached to an inert, insoluble material—such as calcium alginate. This can provide increased resistance to changes in conditions such as pH or temperature.
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What test could you do to prove that Immobilised Enzymes had not contaminated your final product?
Biuret Test - if Enzymes are present, a positive indication (blue to purple) will show if Enzymes are present
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What are the advantages of Immobilised Enzymes?
They don't contaminate the product; used in a continuous process; constantly reusable; more stable than other Enzymes
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How are Enzymes produced?
Culturing microbes in fermentation vessels - microbes produce the enzymes as part of their normal metabolic activity; Enzymes are then purified and can then be added to substrate
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What Enzyme is used to break down proteins (biological detergents)?
Protease (sourced from Bacillus Bacterium)
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What Enzyme is used for sweetening foods and drinks (high fructose syrup)?
Glucose Isomerase (sourced from Fungas Streptomycin)
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What Enzyme is used in Vegetarian Cheese?
Rennin (sourced from Mucor Fungus)
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What Enzyme is used in fruit juice and wine (separates pulp)?
Pectinase (Aspergillus Fungus)
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Why are Enzymes used in large scale industrial productions?
Biological Catalysts; Lower Activation Energies
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Describe the process of Industrial Production
Substrate enters tank; passes through the Immobilised Enzymes; product is released from the bottom
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What are the different processes of Immobilising Enzymes?
Chemically Bonded (cross-linked Enzymes); Adsorption (to stick on, natural only, carrier-bound Enzyme); Entrapment (Enzyme inclusion); Encapsulation in Alginate Beads (microcapsule)
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What are the disadvantages of Immobilising Enzymes?
Adsorption - Enzyme may become detached; Matrix-bed Enzymes may slow down reaction; Alginate Gel alters shape of the Active Site; Chemically Bonding is complex/expensive; contamination is costly
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What is a Biosensor?
A device which uses a living organism or biological molecules, especially enzymes or antibodies, to detect the presence of chemicals: detects low concentrations, highly specific, accurate, quantitative measurement
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From top to bottom, describe a Biosensor
Value displayed as a quantitative number on top; Transducer (converts chemical to electrical energy); Product transported up the tube; Chemically Bonded immobilised Enzymes (react with Substrate); Filter allows through small molecules
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Name the Covalent Bond between two adjacent Amino Acids
Peptide Bonds
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Why should you repeat an investigation at least twice?
Increases reliability; allows a mean to be calculated; identified anomalies
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How do Enzymes bring about their effect of speeding up a reaction?
They lower the Activation Energy of a reaction
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Distinguish between intracellular and extracellular enzymes
Intracellular enzymes are based in a cell (respiratory enzymes (i.e. Lysin)), whilst extracellular enzymes are based outside the cells (digestive enzymes in the alimentary canal)
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State the term given to enzymes which work within specific compartments inside cells
Intracellular enzymes
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Name the bond in an enzyme molecule that is formed from -SH groups
Disulphide
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Suggest why tinned apple does not turn brown
Seal from oxygen; enzymes may be denatured as liquid could be acidic
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What would have been used to control the pH of an enzyme solution?
pH Buffer
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Other cards in this set

Card 2

Front

What are Enzymes?

Back

They are Proteins in their tertiary structure; they are a type of Metabolic (Globular) Protein; they can speed up reactions without being used up

Card 3

Front

What is special about the Active Site?

Back

Preview of the front of card 3

Card 4

Front

Enzyme + Substrate = ?

Back

Preview of the front of card 4

Card 5

Front

What four factors are Enzymes affected by?

Back

Preview of the front of card 5
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